The message below was sent out by President Gee this afternoon. I would encourage everyone to try to attend. If you happen to be there and see me, please come up and say hi. I hope to see you there!
Dear Students and Colleagues:
I write to urge you to support this Monday’s student-led effort to raise money for victims of the recent earthquake in Haiti. All proceeds from the One University, One Cause: Buckeye Benefit Dinner will go to the American Red Cross. Details of the program, including an option for drive-through dinner purchases, are noted below.
As we read and watch the continuing news coverage from Haiti, the scale of the devastation and loss of life has become painfully clear. I have been personally moved by the response of our students, who have effectively combined their compassion, caring, leadership, and great spirit in creating a significant program to help others in need.
Please join me in supporting their good efforts.
Sincerely,
E. Gordon Gee
President
One University, One Cause: A Buckeye Benefit Dinner for Haiti
Monday, Feb. 1, 5 p.m.-8 p.m. in the RPAC’s Tom W. Davis Gym. The $10 dinner will include pasta with marinara sauce (with or without meatballs), salad, garlic bread, and Coca Cola beverages. Tickets are available at the Ohio Union and RPAC information desks; they may also be purchased at the door. Drive-through meals may be purchased along Tuttle Park Drive at the north end of the RPAC. All food, supplies, and labor are being donated.
Additional information: http://www.ohiounion.osu.edu/haiti/
Thursday, January 28, 2010
Transition Metal Report Question Quiz
I have placed a transition metal lab quiz on carmen to take the place of what you would typically submit as report questions. It is slightly different from the Exp #24 titration questions in the fact that there are not numerical questions that I can set up as random number generator questions and give multiple attempts. Because of this, I am limiting you to only have one attempt on the quiz and you will only have 20 minutes to complete it. It is due Monday, February 1st, at midnight.
Here is the grade breakdown and instructions I gave to the TA's to grade the lab:
This experiment is worth 110 total points.
10 pts: Completion of the Packet
I will instruct each student to hand in their completed packets at the beginning of the period they are performing Experiment #26. During the lab period browse through their packet and give them a grade out of 25 based on their effort. If it looks like they have everything completed give them full credit, but if several questions are missing subtract points. These packets should be graded rather quickly. Record the grades in your grade book and hand them back to the students during the same lab period.
Report Sheet
25 pts: Assigning Unknown Complexes
Each spectrum, A – E, is worth five points each.
40 pts: An extensive version of the spectrochemical series
Give the students 10 points for each ligand that is correct situated in the spectrochemical series.
35 pts: Report Question Quiz on Carmen
On Thursday evening I will post a quiz on Carmen titled Transition Metal Quiz. It will be due Monday, February 1st at midnight. These questions, based on the content of the packet, will be graded on accuracy and each student will have only 1 attempt for each quiz with the highest score counting towards the lab report grade. Each quiz will have similar problems, but the values for each problem will be slightly different.
Here is the grade breakdown and instructions I gave to the TA's to grade the lab:
This experiment is worth 110 total points.
10 pts: Completion of the Packet
I will instruct each student to hand in their completed packets at the beginning of the period they are performing Experiment #26. During the lab period browse through their packet and give them a grade out of 25 based on their effort. If it looks like they have everything completed give them full credit, but if several questions are missing subtract points. These packets should be graded rather quickly. Record the grades in your grade book and hand them back to the students during the same lab period.
Report Sheet
25 pts: Assigning Unknown Complexes
Each spectrum, A – E, is worth five points each.
40 pts: An extensive version of the spectrochemical series
Give the students 10 points for each ligand that is correct situated in the spectrochemical series.
35 pts: Report Question Quiz on Carmen
On Thursday evening I will post a quiz on Carmen titled Transition Metal Quiz. It will be due Monday, February 1st at midnight. These questions, based on the content of the packet, will be graded on accuracy and each student will have only 1 attempt for each quiz with the highest score counting towards the lab report grade. Each quiz will have similar problems, but the values for each problem will be slightly different.
Wednesday, January 27, 2010
Lecture #11, Wednesday, January 27th
The main point I have been trying to emphasize to everyone this quarter is to think like a chemist. The tough part about chemistry is that in order to excel at it you need excellent critical thinking and problem solving skills. If you have these skills you will not only be able to use them in this class, but also all of your other classes and you future job(s). The rest of this unit in transition metal chemistry will focus on developing your critical thinking skills.
Our eyes are a complex instrument and are able to detect color in the wavelength range of 400 - 700 nm. In reality, this is just a tiny portion of the electromagnetic spectrum, and we can analyze all the other forms of radiation using advanced scientific instrumentation. The instrument we will focus on in this class is the UV-Vis spectrometer, which can detect radiation in the visible and ultra-violet regions in the spectrum. We can then use this information to analyze the electronic structure of molecules and complex ions. And by electronic structure, I mean how the electrons fill their orbitals, and how much energy it takes to excite electrons from orbital to orbital.
In order to interpret UV-Vis spectra properly and analyze electronic excitations between molecular orbitals, we first need to identify the interactions between orbitals, or how the orbitals overlap. Therefore it is VITAL to know the shapes of the orbitals (in 3-dimensions with phases) and how they are derived. The tutorial shown here will help you do this.
When molecules form they will do anything they can to get all their electrons in the lowest energy possible. To determine the energy, we must analyze the interactions the central atom has with all of its ligands as a unit.
The stronger a bond is, the more stable it is. This lowers the overall energy.
The greater the orbital overlap, the stronger the bond, and the more stable the bonding molecular orbitals become. For a tutorial and overview and a review of what was taught in general chemistry covering molecular orbital theory check this site.
We will be using the topics in those tutorials and taking them one step farther by analyzing the d orbitals in this class. I also posted a handout on carmen discussing molecular orbitals, bonding, MO diagrams, and color. Be sure to read through it.
Our eyes are a complex instrument and are able to detect color in the wavelength range of 400 - 700 nm. In reality, this is just a tiny portion of the electromagnetic spectrum, and we can analyze all the other forms of radiation using advanced scientific instrumentation. The instrument we will focus on in this class is the UV-Vis spectrometer, which can detect radiation in the visible and ultra-violet regions in the spectrum. We can then use this information to analyze the electronic structure of molecules and complex ions. And by electronic structure, I mean how the electrons fill their orbitals, and how much energy it takes to excite electrons from orbital to orbital.
In order to interpret UV-Vis spectra properly and analyze electronic excitations between molecular orbitals, we first need to identify the interactions between orbitals, or how the orbitals overlap. Therefore it is VITAL to know the shapes of the orbitals (in 3-dimensions with phases) and how they are derived. The tutorial shown here will help you do this.
When molecules form they will do anything they can to get all their electrons in the lowest energy possible. To determine the energy, we must analyze the interactions the central atom has with all of its ligands as a unit.
The stronger a bond is, the more stable it is. This lowers the overall energy.
The greater the orbital overlap, the stronger the bond, and the more stable the bonding molecular orbitals become. For a tutorial and overview and a review of what was taught in general chemistry covering molecular orbital theory check this site.
We will be using the topics in those tutorials and taking them one step farther by analyzing the d orbitals in this class. I also posted a handout on carmen discussing molecular orbitals, bonding, MO diagrams, and color. Be sure to read through it.
Midterm #1 Review Session
The review session for the first midterm will be held on Monday, February 1st, at 8:00 pm in 1000 McPhrson.
My review sessions are held to answer any questions that you have and I will not come with any prepared material.
My review sessions are held to answer any questions that you have and I will not come with any prepared material.
Monday, January 25, 2010
Transition Metal Homework Set
There were a few small errors on the HW set for transition metals. I have fixed them and posted the new key on carmen.
Quiz III Study Guide
Quiz III will be primarily be based on the transition metal lab. Be sure to read through and understand all the concepts involved. Also be aware that the quiz will take place in the last twenty minutes in lab so there is no advantage to finish early because you are forced to stay to the end regardless. If you happen to finish the lab early you can work on the homework set or any other problems with your group members.
Lecture #10, Monday, January 25th
Lecture started with looking into stereochemistry of transition metal complexes. We discussed how to determine the difference between square planar and tetrahedral complexes, skipped over the ML5 complexes, and will analyze ML6 octahedral complexes in detail in the lab.
Isomers were then discussed and Table 24.17 on page 1027 gives a flow chart similar to what I discussed in class. The isomers we are concerned with in class are: linkage, coordination sphere, hydration, geometric (cis/trans), and optical (enantiomers).
On Wednesday we will discuss how our eyes detect color and how we can relate that to the orbital interactions in transition metal complexes. This will lead us into a discussion of bonding theories in transition metal complexes.
Songs played before class:
Bruce Springsteen - Born To Run
Isomers were then discussed and Table 24.17 on page 1027 gives a flow chart similar to what I discussed in class. The isomers we are concerned with in class are: linkage, coordination sphere, hydration, geometric (cis/trans), and optical (enantiomers).
On Wednesday we will discuss how our eyes detect color and how we can relate that to the orbital interactions in transition metal complexes. This will lead us into a discussion of bonding theories in transition metal complexes.
Songs played before class:
Bruce Springsteen - Born To Run
Lecture #9, Friday, January 22nd
Coordination compounds contain a transition metal central atom with ligands coordinated to it through coordinate covalent bonds. Complex ions exist in solution as either positive or negative ions and form salts in the same manner as sodium chloride. Shown here is the crystal structure for NaCl and when we place it in water, it will dissolve into Na+ and Cl- ions. Coordination complexes behave in the exact same manner, but the ions are typically much more complex.
For example, [Co(NH3)6]Cl3 has a crystal structure shown here and dissolves into these ions in solution. It's the same principle, but things are a little more complicated. This forces us to come up with a system to identify and draw these complex ions in solution. Chemists use brackets to indicate the identity of the complex ion and outside the brackets is the counter ion. When you are asked for the coordination number of the transition metal cation you must only consider the ligands inside the brackets, but in order to determine the charge of the transition metal cation you must consider both the ligands inside the brackets and the counter ion.
I then discussed the early discoveries of Alfred Werner and showed how he came up with a reason for the different physical properties of various complexes by looking at the bonding at the transition metal center. He concluded that complexes can exist as isomers, or more specifically -cis and -trans.
We then showed how ligands bond to the transition metal centers through their lone pairs. In lab you will analyze various ligands and you are responsible for knowing the identity, charge, and which atoms in the ligand bind to the transition metal for the ligands listed in Table 24.2 on page 1019 of the text.
I also gave out the rules for naming transition metal complexes and worked through a few examples. You will need this information to complete the lab this week.
Songs played before class:
Bob Seger - Hollywood Nights
Rihanna ft. T.I. - Live Your Life lyrics
For example, [Co(NH3)6]Cl3 has a crystal structure shown here and dissolves into these ions in solution. It's the same principle, but things are a little more complicated. This forces us to come up with a system to identify and draw these complex ions in solution. Chemists use brackets to indicate the identity of the complex ion and outside the brackets is the counter ion. When you are asked for the coordination number of the transition metal cation you must only consider the ligands inside the brackets, but in order to determine the charge of the transition metal cation you must consider both the ligands inside the brackets and the counter ion.
6%5DCl3%20unit%20cell.JPG){kind=link}
I then discussed the early discoveries of Alfred Werner and showed how he came up with a reason for the different physical properties of various complexes by looking at the bonding at the transition metal center. He concluded that complexes can exist as isomers, or more specifically -cis and -trans.
We then showed how ligands bond to the transition metal centers through their lone pairs. In lab you will analyze various ligands and you are responsible for knowing the identity, charge, and which atoms in the ligand bind to the transition metal for the ligands listed in Table 24.2 on page 1019 of the text.
I also gave out the rules for naming transition metal complexes and worked through a few examples. You will need this information to complete the lab this week.
Songs played before class:
Bob Seger - Hollywood Nights
Rihanna ft. T.I. - Live Your Life lyrics
Wednesday, January 20, 2010
Experiment #26 Pre-Lab
In order for a pre-lab for Exp #26 to make any sense, you need to first perform the solubility tests from page 93 of the procedure. A nice outline of what you need to look for is on page 88. Write down a detailed description of the physical appearance of your unknown and once you narrow down your options for your unknown salt (as outlined last week in lecture) check the physical properties of inorganic compounds in the CRC to try and narrow down your unknown even more. You should complete all this as soon as you finish Exp #25 III. You will have two lab periods to perform the test and identify your unknown salt, so you need to come up with a plan in order to finish.
You can write out the pre-lab on a piece of paper or you can write it out in your lab notebook. Whatever you prefer would work just fine. Your TA will walk around the lab during the assigned periods to check things out.
Note: Remember that we are performing the transition metal lab next week and Exp #26 will come the following week.
You can write out the pre-lab on a piece of paper or you can write it out in your lab notebook. Whatever you prefer would work just fine. Your TA will walk around the lab during the assigned periods to check things out.
Note: Remember that we are performing the transition metal lab next week and Exp #26 will come the following week.
Lecture #8, Wednesday, January 20th
Today I finished the solubility unit by working out an example involving fractional/selective precipitation. If you are keeping up with the material, at this point you should be able to handle any of the problems from the solubility set.
The next unit we will discuss is Coordination Chemistry or the Chemistry of Transition Metals. We will discuss the bonding and properties of the complex ions we have been observing in the Qualitative Analysis lab and will give a reason for why Ni(NH3)62+ is blue Co(NH3)62+ is pink, and Zn(NH3)62+ is clear or colorless.
In order to analyze these complexes we must first have a firm grasp of the electron configurations of transition metal ions. When a transition metal forms a cation or a complex, it will ALWAYS lose its s electrons first, then its d electrons. When we detect color with our eyes, complexes absorb photons of visible light. This is due to an electron being excited from one molecular orbital to another. In order to analyze the excitations occurring in transition metal complexes we must first know how many electrons they have. So take a look at the transition metal homework set and start by writing out the proper electron configurations for each cation. You will need to know this information.
We will start Friday's lecture by discussing coordination compounds and we will analyze how they form by looking into the ligands that will attach to them.
Music played before lecture:
I totally blew it today trying to hook up the laptop, which didn't even work. I'll attempt that demo again next week.
The next unit we will discuss is Coordination Chemistry or the Chemistry of Transition Metals. We will discuss the bonding and properties of the complex ions we have been observing in the Qualitative Analysis lab and will give a reason for why Ni(NH3)62+ is blue Co(NH3)62+ is pink, and Zn(NH3)62+ is clear or colorless.
In order to analyze these complexes we must first have a firm grasp of the electron configurations of transition metal ions. When a transition metal forms a cation or a complex, it will ALWAYS lose its s electrons first, then its d electrons. When we detect color with our eyes, complexes absorb photons of visible light. This is due to an electron being excited from one molecular orbital to another. In order to analyze the excitations occurring in transition metal complexes we must first know how many electrons they have. So take a look at the transition metal homework set and start by writing out the proper electron configurations for each cation. You will need to know this information.
We will start Friday's lecture by discussing coordination compounds and we will analyze how they form by looking into the ligands that will attach to them.
Music played before lecture:
I totally blew it today trying to hook up the laptop, which didn't even work. I'll attempt that demo again next week.
Pre-Health Organization
*It is an academic pre-health organization called Delta Omega Kappa for women that are enrolled at OSU that does sorority-like functions.
*We welcome any one with a pre-health major (anywhere from psychology, pre-dentistry, pre-med, nursing, EEOB, any many more!)
*We are the ONLY pre-health sorority on campus.
*Anyone who is interested can come to our rush event Wednesday, January 20 at 7:00 PM at 1951 Indianola Avenue.
*Feel free to bring friends! Casual dress is perfectly fine! Beverages and snacks will be provided.
*Contact Meredith Greene (greene.758@buckeyemail.osu.edu) or our Rush Chair, Joline Tellechea (tellechea.1@buckeyemail.osu.edu) for any questions!
*We welcome any one with a pre-health major (anywhere from psychology, pre-dentistry, pre-med, nursing, EEOB, any many more!)
*We are the ONLY pre-health sorority on campus.
*Anyone who is interested can come to our rush event Wednesday, January 20 at 7:00 PM at 1951 Indianola Avenue.
*Feel free to bring friends! Casual dress is perfectly fine! Beverages and snacks will be provided.
*Contact Meredith Greene (greene.758@buckeyemail.osu.edu) or our Rush Chair, Joline Tellechea (tellechea.1@buckeyemail.osu.edu) for any questions!
Monday, January 18, 2010
CRC Handbook On-line for Exp #26
The pre-lab for experiment #26 instructs you to use the CRC handbook of Chemistry and Physics. This is a very powerful resource for many scientists.
“The CRC Handbook provides broad coverage of all types of physical science data commonly encountered by scientists and engineers. Notwithstanding the growing availability of specialized databases on the Internet, we feel there is still a need for a concise, reliable reference source spanning the full range of the physical sciences and focusing on key data that are frequently needed by R&D professionals, engineers, and students. The CRC Handbook, in its print, CD-ROM, and Internet formats, is aimed at serving these needs. The data contained in the Handbook have been carefully evaluated by experts in each field; quality control is a high priority and the sources are documented. The annual updates make it possible to add new and improved data in a timely fashion.”
David R. Lide, ed., CRC Handbook of Chemistry and Physics, 89th Edition,
CRC Press/Taylor and Francis, Boca Raton, FL.
Every chemist in the world has used the CRC Handbook at one time in their academic career. It is an absolute must have for every research group. Its contents are jam packed with so much valuable information. Of particular interest for this lab are the physical and chemical properties of the chemicals listed in Table 1. Throughout all three general chemistry courses you will frequently use the CRC Handbook, so be sure to familiarize yourself with it.
Copies of the CRC Handbook can be found on the first floor of the Science and Engineering Library, but we are currently moving towards solely using the on-line version, which is very easy to access. If you login to this course on carmen click on the Library link on the top red tool bar and this page should pop up. Be sure to check out the recommended links posted by the library and they will definitely help whenever you are instructed to use the CRC Handbook.
The physical properties of inorganic compounds link is most useful for this experiment.
“The CRC Handbook provides broad coverage of all types of physical science data commonly encountered by scientists and engineers. Notwithstanding the growing availability of specialized databases on the Internet, we feel there is still a need for a concise, reliable reference source spanning the full range of the physical sciences and focusing on key data that are frequently needed by R&D professionals, engineers, and students. The CRC Handbook, in its print, CD-ROM, and Internet formats, is aimed at serving these needs. The data contained in the Handbook have been carefully evaluated by experts in each field; quality control is a high priority and the sources are documented. The annual updates make it possible to add new and improved data in a timely fashion.”
David R. Lide, ed., CRC Handbook of Chemistry and Physics, 89th Edition,
CRC Press/Taylor and Francis, Boca Raton, FL.
Every chemist in the world has used the CRC Handbook at one time in their academic career. It is an absolute must have for every research group. Its contents are jam packed with so much valuable information. Of particular interest for this lab are the physical and chemical properties of the chemicals listed in Table 1. Throughout all three general chemistry courses you will frequently use the CRC Handbook, so be sure to familiarize yourself with it.
Copies of the CRC Handbook can be found on the first floor of the Science and Engineering Library, but we are currently moving towards solely using the on-line version, which is very easy to access. If you login to this course on carmen click on the Library link on the top red tool bar and this page should pop up. Be sure to check out the recommended links posted by the library and they will definitely help whenever you are instructed to use the CRC Handbook.
The physical properties of inorganic compounds link is most useful for this experiment.
Lecture #7, Monday, January 18th
Classes and labs were canceled today to observe the Martin Luther King Jr. holiday.
Labs will not be in session on Tuesday, Jan. 19th as well.
Labs will not be in session on Tuesday, Jan. 19th as well.
Quiz II Study Guide
For the Quiz this week focus on questions 24 - 57 and 72 - 83 from the solubility homework set, which is posted on carmen.
Again, like I said in class, I expect you to know the concepts from the homework sets and since I do not collect them or grade them for accuracy, the purpose of the quizzes are to test you to see if you understand the concepts in the homework sets.
Again, like I said in class, I expect you to know the concepts from the homework sets and since I do not collect them or grade them for accuracy, the purpose of the quizzes are to test you to see if you understand the concepts in the homework sets.
Lecture #6, Friday, January 15th
We continued with the effect complex ions have on solubility and performed an example problem asking us to calculate the concentration of a metal ion in solution after the complex ion formed. We then discussed a special case of complex ion formation referred to as amphoterism. We performed a rather complex example analyzing the solubility of Al(OH3 in basic solution. Be sure to know how to perform examples of both types for the quiz this week.
We will finish the solubility unit on Wed. by briefly discussing fractional/selective precipitation and then we will start the transition metal unit.
Songs played before class:
Out Last night - Kenny Chesney
Paralyzer - Finger Eleven
We will finish the solubility unit on Wed. by briefly discussing fractional/selective precipitation and then we will start the transition metal unit.
Songs played before class:
Out Last night - Kenny Chesney
Paralyzer - Finger Eleven
Wednesday, January 13, 2010
Lecture #5, Wednesday, January 13th
Lecture started off by continuing with the influence of pH on the solubility of slightly soluble salts. By adjusting the pH, chemists have an excellent way to manipulate the solubility.
If you are asked if HCl (or any other reagent) would increase, decrease, or have no effect on the solubility of say, zinc hydroxide, the very first and most important thing you want to do is WRITE OUT THE SOLUBILITY EQUILIBRIUM. Remember, we are trying to manipulate the equilibrium, so it makes sense to write out the balanced equation first.
The second step is to identify if any of the cations/anions dissolved are acidic or basic. This requires a knowledge of the strong acids and strong bases. Remember from Chem 122 that the conjugate acid of a strong base is neutral and the conjugate base of a strong acid is also neutral. The general rule of thumb is: "The stronger the acid, the weaker the conjugate base and the stronger the base, the weaker the conjugate acid."
To a first approximation we can use Le Chatlier's principle to determine how an equilibrium will shift upon the addition of an acid or base. Acids neutralize bases (lower the hydroxide concentration) and bases neutralize acids (lower the hydrogen ion concentration). This can have a dramatic effect on the molar solubility. The calculations in class showed that at a pH = 7.0, the solubility of zinc hydroxide is 8.9 x 10-7 grams in 4 mL of solution. But if the pH is adjusted to 6.0 then we can dissolve 0.0179 grams of zinc hydroxide in 4 mL of this solution. The take home message here is that pH plays a huge role in the solubility of slightly soluble salts and with this knowledge at our disposal, we can manipulate the solubility equilibrium by adding acidic or basic reagents.
Notice that in the previous paragraph I used the phrase "to a first approximation." Sometimes, based on fundamental principles, things happen that we do not expect. For example if you add concentrated ammonia (a base) to zinc hydroxide, Le Chatlier's principle would predict that the equilibrium will shift to make the zinc hydroxide less soluble. Experimentally, when ammonia is added to zinc hydroxide we observe a large increase in solubility.
Initially this was frustrating to chemists as they tried to come up with a theory for why this was happening. The theory we can use to explain this observation is "complex ion formation." If you have been paying attention you will have heard this term mentioned several times this quarter, but now we will investigate how and why complex ions form.
This opened up a whole new branch of chemistry as complex ions are sometimes referred to as coordination compounds, which involve a transition metal center attached to ligands (surrounding atoms/ions/molecules). This branch of chemistry dealing with transition metal, or coordination complexes, is inorganic chemistry (which is my favorite of all the chemistry subdivisions if you happen to be scoring at home).
We will go over several examples in lecture talking about coordination complexes and how complex ion formation shifts the resulting equilibrium expressions. Then we will discuss more on selective precipitation, which wraps up the solubility "unit." We will then transition to coordination compounds and investigate how and why a transition metal bonds to form a complex ion or compound.
Songs played before class:
KE$HA - TiK ToK (Apparently Dr. Zellmer is not very find of this song)
The Killers - All These Things That I've Done
If you are asked if HCl (or any other reagent) would increase, decrease, or have no effect on the solubility of say, zinc hydroxide, the very first and most important thing you want to do is WRITE OUT THE SOLUBILITY EQUILIBRIUM. Remember, we are trying to manipulate the equilibrium, so it makes sense to write out the balanced equation first.
The second step is to identify if any of the cations/anions dissolved are acidic or basic. This requires a knowledge of the strong acids and strong bases. Remember from Chem 122 that the conjugate acid of a strong base is neutral and the conjugate base of a strong acid is also neutral. The general rule of thumb is: "The stronger the acid, the weaker the conjugate base and the stronger the base, the weaker the conjugate acid."
To a first approximation we can use Le Chatlier's principle to determine how an equilibrium will shift upon the addition of an acid or base. Acids neutralize bases (lower the hydroxide concentration) and bases neutralize acids (lower the hydrogen ion concentration). This can have a dramatic effect on the molar solubility. The calculations in class showed that at a pH = 7.0, the solubility of zinc hydroxide is 8.9 x 10-7 grams in 4 mL of solution. But if the pH is adjusted to 6.0 then we can dissolve 0.0179 grams of zinc hydroxide in 4 mL of this solution. The take home message here is that pH plays a huge role in the solubility of slightly soluble salts and with this knowledge at our disposal, we can manipulate the solubility equilibrium by adding acidic or basic reagents.
Notice that in the previous paragraph I used the phrase "to a first approximation." Sometimes, based on fundamental principles, things happen that we do not expect. For example if you add concentrated ammonia (a base) to zinc hydroxide, Le Chatlier's principle would predict that the equilibrium will shift to make the zinc hydroxide less soluble. Experimentally, when ammonia is added to zinc hydroxide we observe a large increase in solubility.
Initially this was frustrating to chemists as they tried to come up with a theory for why this was happening. The theory we can use to explain this observation is "complex ion formation." If you have been paying attention you will have heard this term mentioned several times this quarter, but now we will investigate how and why complex ions form.
This opened up a whole new branch of chemistry as complex ions are sometimes referred to as coordination compounds, which involve a transition metal center attached to ligands (surrounding atoms/ions/molecules). This branch of chemistry dealing with transition metal, or coordination complexes, is inorganic chemistry (which is my favorite of all the chemistry subdivisions if you happen to be scoring at home).
We will go over several examples in lecture talking about coordination complexes and how complex ion formation shifts the resulting equilibrium expressions. Then we will discuss more on selective precipitation, which wraps up the solubility "unit." We will then transition to coordination compounds and investigate how and why a transition metal bonds to form a complex ion or compound.
Songs played before class:
KE$HA - TiK ToK (Apparently Dr. Zellmer is not very find of this song)
The Killers - All These Things That I've Done
Monday, January 11, 2010
Initial Course Survey Comments
I finally had the chance to go through the surveys everyone filled out the first day of class. I read each and every one of them and here are some of the more interesting facts/comments I took from them:
The first question asked the grade you earned in 121/122 and what you expected to earn in 123. 39 students tested out of both 121 and 122 (by EM credit or AP credit. To be honest I'm not sure what the difference is between the two) and 32 students tested out of 121 and then went on to take 122 here.
On thing that always stands out to me in asking this question is that some students will earn a C- in 121, a D+ in 122, then expect to earn an A in 123. I don't really want to put anyone down, but I do not think that is a realistic expectation. Chemistry 123 builds off both courses and there is information from each that you will need to apply in this course. For instance, in this last section of Chapter 17 and the titration lab there are several concepts we applied from chapter 4 as well as equilibrium expression discussed in chapter 14 and at the beginning of chapter 17. Almost concept we discuss in this class builds off of something else and I will do my best to highlight what you need to review from previous quarters.
The next question I asked is how many hours per week you plan to study. Some people try to come up with this magical formula of how many hours outside the classroom you should study for every hour inside the classroom. I don't really buy into this theory because every student is different. It's also really not how much you study, but it's the quality of studying that matters. If you read Chapter 17 of the text and don't understand a thing you read after reading the chapter, that doesn't count as your time of "studying." I would start by performing the old exam questions that are posted on Carmen. After you do all those problems and get a feel for the content of them, then go read the text. Things will make much more sense if you have a grasp of the material when you are reading.
One last thing I will say is that if you put down an A as your expected grade, I would think that you will have to devote more than 5 hours a week towards studying.
Med school and Pre-med is the most common response to the career plan question. Remember that medical schools will look highly upon the grade you earn in general chemistry (and organic chemistry) and whether you plan on going to med school, dental school, optometry school, pharmacy school, etc. all of these professional schools have a large portion of their standardized exams devoted to general chemistry. All of the questions you will see on these exams are considered to be "trick" questions to most students, which will not test you on your ability to regurgitate knowledge, but will test you on whether or not you know the concepts asked in the questions inside and out. So keep that in mind if you are planning on taking one of these exams.
I have a fantastic list of songs to play before class based on your responses. I try to play a wide selection of music before class, but I will definitely be biased towards country and rap, which are my favorites. Here is a list of what I enjoy...
Favorite Songs: Anything country especially Dierks Bentley and Brad Paisley. I'm starting to take a liking to rap a little more these days and nothing gets me fired up more than listening to the Ohio State marching band.
Favorite TV Shows: Anything ESPN: SportsCenter, Baseball Tonight, Pardon the Interuption, How I Met Your Mother, Big Bang Theory, The Office, House, Seinfeld, and Everybody Loves Raymond.
Favorite Movies: The Hangover, Wedding Crashers, Fever Pitch, Dead Poets Society, Good Will Hunting, and Mona Lisa Smile.
I played a clip of House during class the other day and I am definitely looking to add others if they fit in well. If you have a movie quote or clip that you think would be a great fit to play in class please let me know. I would LOVE to somehow include a movie like The Hangover or Wedding Crashers somehow.
Here are my replies to some of your comments. The student comments are in bold.
I've heard you are challenging but fair in your exams and quizzes.
My quizzes will basically test your understanding of the homework problems. I like to give you a set of problems to focus on and I will pull questions from that set. I could also give you a problem I highlight in lecture. There won't be anything too out of the ordinary, but every once in a while I do like to push the envelope and ask you a problem that you have never seen before. Remember, to be a good chemist you need to solve problems, not memorizing information.
I've heard tons of rumors from it's an easy A to a tough C
This really depends on who you talk to. I don't know many students who would consider any gen chem class as an "easy A." Remember that C is average and that based on what how the general chemistry department assigns the grades, a large portion of you will earn a C.
I've hear some scary things about Chem 123. I often hear it referred to as a "weed out" class and know several people who changed their major because of it.
Keep in mind that chemistry is the “central science” and many majors require students to take general chemistry to ensure that students in their field meet a certain standard of excellence. You may have heard this referred to as a weed out process, but we need our doctors and engineers to be the best of the best. As a student in the sciences you will not only be competing against the top students in this country, but also around the world.
Heard this class was easier than 122, but not an "easy A." There was nothing I really enjoyed from the previous classes except for the demonstrations.
I'm not really sure why students say 123 is "easier" than 122, except for the fact that 122 is almost all mathematical problems. 123 s a mix of math problems and also some conceptual work. If you are not exceptional at math you probably did not like 122 at all. At least that is my guess. I also hate to be the bearer of bad news, but I typically do not do any demonstrations at all. I just feel they are there for entertainment purposes. Remember, I am not here to entertain you. I am here to teach you. If I really felt students learned a lot from demos I would perform more of them, but I think that in the long run you are better served as a student to see more example problems than demos. I will try my best to throw a joke or say something obscenely stupid from time to time to keep you on your toes :)
Like all the general chemistry classes here at OSU, the rumors I've heard about 123 aren't the greatest. I've heard most people do poorly with 1 or 2 A's.
Here is the breakdown from last winter's class of 221 students:
12 A (5.4%)
19 A- (8.5%)
26 B+ (11.8%)
22 B (9.9%)
29 B- (13.1%)
18 C+ (8.1%)
36 C (16.2%)
27 C- (12.2%)
9 D+ (4.0%)
8 D (3.6%)
15 E (6.8%)
The grade distribution is based on a formula devised by the general chemistry department and will be assessed to your final grade (out of 1000 points).
Labs were pointless and mind numbing
I'm really hoping to change this opinion of the labs. I know the first one was a little rough around the edges, but Exp #25 has been cut down considerably to open up more time to UNDERSTAND the concepts in the labs as you go along. This means you will be preforming questions in the lab setting and completing on-line report questions. I am also excited to have everyone perform the solar cell lab, which will hopefully show you what it's like to tie various general chemistry concepts together in a practical manner.
I am really looking forward to this class and heard you were a great teacher.
I hope this one is not a rumor. I am really passionate about what I do and I hope I can portray that attitude throughout the quarter. I hope we can really improve the labs and have you learn from them, and more importantly you will learn while you are doing them.
Please also know that the only way to improve the labs is to have constructive comments from the students. I am here to work for you and I always try to keep the students first. I hope to teach you a great deal of information and I really hope that you can learn information in this class that you can take with you the rest of your life. I might try to change things up from time to time, and I know that change doesn't go over well, but I am doing it with your best interests in mind. I am not out to get you and I will do anything to work with you. I am really looking forward to this quarter and I can't wait to get started.
I will see everyone in class on Wed, Dr. Fus
The first question asked the grade you earned in 121/122 and what you expected to earn in 123. 39 students tested out of both 121 and 122 (by EM credit or AP credit. To be honest I'm not sure what the difference is between the two) and 32 students tested out of 121 and then went on to take 122 here.
On thing that always stands out to me in asking this question is that some students will earn a C- in 121, a D+ in 122, then expect to earn an A in 123. I don't really want to put anyone down, but I do not think that is a realistic expectation. Chemistry 123 builds off both courses and there is information from each that you will need to apply in this course. For instance, in this last section of Chapter 17 and the titration lab there are several concepts we applied from chapter 4 as well as equilibrium expression discussed in chapter 14 and at the beginning of chapter 17. Almost concept we discuss in this class builds off of something else and I will do my best to highlight what you need to review from previous quarters.
The next question I asked is how many hours per week you plan to study. Some people try to come up with this magical formula of how many hours outside the classroom you should study for every hour inside the classroom. I don't really buy into this theory because every student is different. It's also really not how much you study, but it's the quality of studying that matters. If you read Chapter 17 of the text and don't understand a thing you read after reading the chapter, that doesn't count as your time of "studying." I would start by performing the old exam questions that are posted on Carmen. After you do all those problems and get a feel for the content of them, then go read the text. Things will make much more sense if you have a grasp of the material when you are reading.
One last thing I will say is that if you put down an A as your expected grade, I would think that you will have to devote more than 5 hours a week towards studying.
Med school and Pre-med is the most common response to the career plan question. Remember that medical schools will look highly upon the grade you earn in general chemistry (and organic chemistry) and whether you plan on going to med school, dental school, optometry school, pharmacy school, etc. all of these professional schools have a large portion of their standardized exams devoted to general chemistry. All of the questions you will see on these exams are considered to be "trick" questions to most students, which will not test you on your ability to regurgitate knowledge, but will test you on whether or not you know the concepts asked in the questions inside and out. So keep that in mind if you are planning on taking one of these exams.
I have a fantastic list of songs to play before class based on your responses. I try to play a wide selection of music before class, but I will definitely be biased towards country and rap, which are my favorites. Here is a list of what I enjoy...
Favorite Songs: Anything country especially Dierks Bentley and Brad Paisley. I'm starting to take a liking to rap a little more these days and nothing gets me fired up more than listening to the Ohio State marching band.
Favorite TV Shows: Anything ESPN: SportsCenter, Baseball Tonight, Pardon the Interuption, How I Met Your Mother, Big Bang Theory, The Office, House, Seinfeld, and Everybody Loves Raymond.
Favorite Movies: The Hangover, Wedding Crashers, Fever Pitch, Dead Poets Society, Good Will Hunting, and Mona Lisa Smile.
I played a clip of House during class the other day and I am definitely looking to add others if they fit in well. If you have a movie quote or clip that you think would be a great fit to play in class please let me know. I would LOVE to somehow include a movie like The Hangover or Wedding Crashers somehow.
Here are my replies to some of your comments. The student comments are in bold.
I've heard you are challenging but fair in your exams and quizzes.
My quizzes will basically test your understanding of the homework problems. I like to give you a set of problems to focus on and I will pull questions from that set. I could also give you a problem I highlight in lecture. There won't be anything too out of the ordinary, but every once in a while I do like to push the envelope and ask you a problem that you have never seen before. Remember, to be a good chemist you need to solve problems, not memorizing information.
I've heard tons of rumors from it's an easy A to a tough C
This really depends on who you talk to. I don't know many students who would consider any gen chem class as an "easy A." Remember that C is average and that based on what how the general chemistry department assigns the grades, a large portion of you will earn a C.
I've hear some scary things about Chem 123. I often hear it referred to as a "weed out" class and know several people who changed their major because of it.
Keep in mind that chemistry is the “central science” and many majors require students to take general chemistry to ensure that students in their field meet a certain standard of excellence. You may have heard this referred to as a weed out process, but we need our doctors and engineers to be the best of the best. As a student in the sciences you will not only be competing against the top students in this country, but also around the world.
Heard this class was easier than 122, but not an "easy A." There was nothing I really enjoyed from the previous classes except for the demonstrations.
I'm not really sure why students say 123 is "easier" than 122, except for the fact that 122 is almost all mathematical problems. 123 s a mix of math problems and also some conceptual work. If you are not exceptional at math you probably did not like 122 at all. At least that is my guess. I also hate to be the bearer of bad news, but I typically do not do any demonstrations at all. I just feel they are there for entertainment purposes. Remember, I am not here to entertain you. I am here to teach you. If I really felt students learned a lot from demos I would perform more of them, but I think that in the long run you are better served as a student to see more example problems than demos. I will try my best to throw a joke or say something obscenely stupid from time to time to keep you on your toes :)
Like all the general chemistry classes here at OSU, the rumors I've heard about 123 aren't the greatest. I've heard most people do poorly with 1 or 2 A's.
Here is the breakdown from last winter's class of 221 students:
12 A (5.4%)
19 A- (8.5%)
26 B+ (11.8%)
22 B (9.9%)
29 B- (13.1%)
18 C+ (8.1%)
36 C (16.2%)
27 C- (12.2%)
9 D+ (4.0%)
8 D (3.6%)
15 E (6.8%)
The grade distribution is based on a formula devised by the general chemistry department and will be assessed to your final grade (out of 1000 points).
Labs were pointless and mind numbing
I'm really hoping to change this opinion of the labs. I know the first one was a little rough around the edges, but Exp #25 has been cut down considerably to open up more time to UNDERSTAND the concepts in the labs as you go along. This means you will be preforming questions in the lab setting and completing on-line report questions. I am also excited to have everyone perform the solar cell lab, which will hopefully show you what it's like to tie various general chemistry concepts together in a practical manner.
I am really looking forward to this class and heard you were a great teacher.
I hope this one is not a rumor. I am really passionate about what I do and I hope I can portray that attitude throughout the quarter. I hope we can really improve the labs and have you learn from them, and more importantly you will learn while you are doing them.
Please also know that the only way to improve the labs is to have constructive comments from the students. I am here to work for you and I always try to keep the students first. I hope to teach you a great deal of information and I really hope that you can learn information in this class that you can take with you the rest of your life. I might try to change things up from time to time, and I know that change doesn't go over well, but I am doing it with your best interests in mind. I am not out to get you and I will do anything to work with you. I am really looking forward to this quarter and I can't wait to get started.
I will see everyone in class on Wed, Dr. Fus
Experiment #25 I, II, and III Grading Rubric
If you look on Page 6 of the syllabus, you will see the grade breakdown for Experiments 25-I, 25-II, and 25-III. It also indicates that the storeroom will be grading each of these lab reports. You will not have to hand in any formal report for these labs, just the report sheet with proper flow chart and the white card attached to it, which your TA has up at their lab station.
The grade breakdown is as follows:
25 Group I
10 pts: Lab Notebook
In the lab notebook section you should write out an outline of the procedure (ask your TA what they expect for this section as they are assigning the grade and their styles will vary). You should also write down all observations in the lab notebook, which will lead you to your conclusions. You need to sign the bottom of each page and your TA also needs to initial and date each page. Once both of you sign off you will hand your carbon copy sheets to your TA.
20 pts: Prelab Assignment
This prelab assignment will be graded by your TA at the beginning of the lab period. They will point out any places where you might need to modify your procedure or give any helpful hints. You can complete this in your lab notebook or on the sheet handed out to you.
100 pts: Proper Identification of Cations Present
Each cation is worth 50 points for Group I. You will get points for correctly identifying whether a cation is present or absent. For example, if you think both lead and silver are present in your sample and only lead is present, then you will receive 50 pts for properly identifying lead and 0 points for improperly identifying silver.
25 Group II
10 pts: Lab Notebook
20 pts: Prelab Assignment
120 pts: Proper Identification of Cations Present
There are 4 cations you are responsible for in Group II. Each one is worth 30 points.
25 Group III
10 pts: Lab Notebook
20 pts: Prelab Assignment
120 pts: Proper Identification of Cations Present
There are 4 cations you are responsible for in Group III. Each one is worth 30 points.
The report sheets are turned in to the TA in the same fashion as Group I.
The deadline for handing in unknowns for Group I, II, and III is 5:30 pm on Jan. 22nd.
The grade breakdown is as follows:
25 Group I
10 pts: Lab Notebook
In the lab notebook section you should write out an outline of the procedure (ask your TA what they expect for this section as they are assigning the grade and their styles will vary). You should also write down all observations in the lab notebook, which will lead you to your conclusions. You need to sign the bottom of each page and your TA also needs to initial and date each page. Once both of you sign off you will hand your carbon copy sheets to your TA.
20 pts: Prelab Assignment
This prelab assignment will be graded by your TA at the beginning of the lab period. They will point out any places where you might need to modify your procedure or give any helpful hints. You can complete this in your lab notebook or on the sheet handed out to you.
100 pts: Proper Identification of Cations Present
Each cation is worth 50 points for Group I. You will get points for correctly identifying whether a cation is present or absent. For example, if you think both lead and silver are present in your sample and only lead is present, then you will receive 50 pts for properly identifying lead and 0 points for improperly identifying silver.
25 Group II
10 pts: Lab Notebook
20 pts: Prelab Assignment
120 pts: Proper Identification of Cations Present
There are 4 cations you are responsible for in Group II. Each one is worth 30 points.
25 Group III
10 pts: Lab Notebook
20 pts: Prelab Assignment
120 pts: Proper Identification of Cations Present
There are 4 cations you are responsible for in Group III. Each one is worth 30 points.
The report sheets are turned in to the TA in the same fashion as Group I.
The deadline for handing in unknowns for Group I, II, and III is 5:30 pm on Jan. 22nd.
Lecture #4, Monday, January 11th
Today's class started with the calculations coming from pages 50 - 52 of the lab manual and it shows us how the Group II and Group III ions are separated.
Be sure to look over these pages of the lab manual and to read the class notes on this material and I want you to know how to:
1. Given a cation, tell whether it will be included in Group II or Group III based on the experimental conditions in Lab #25.
2. If a cation is in Group III, be able to calculate the pH at which its sulfide will precipitate out of solution.
For #1 you will need to know how to calculate Q and then compare it to the Ksp table and for #2 use the method outlined in class today for Fe2+ for all the other cations. Homework problems 72 - 79 should be a great help in understanding these concepts.
For pretty much the rest of the week we will investigate the following factors that influence solubility:
1. Common Ion Effect
2. pH
3. Complex Ion Formation
4. Amphoterism
I did a calculation in the notes showing the influence of a common ion and we will extend this to discuss pH effects. You MUST know the strong acids and bases and they can be found here. We will use them to identify if the conjugate of a strong acid/base is acidic, basic, or neutral and equipped with that information we can answer questions as to whether certain reagents will increase, decrease, or have no effect on the solubility of certain slightly soluble salts.
I finished the last 5 min of class by discussing which steps you can skip for the Group III analysis with Ni2+, Co2+, and Zn2+. Remember that your unknown will not contain Zn2+ so we can skip quite a few steps. Be sure to look at the conformation tests for Ni2+ and Co2+ and determine a method for how to identify them.
Lastly, Quiz I given at the beginning of lab this week will include all material up to last Friday's lecture (Lecture #3). This material also includes comparing Q vs. K, which is homework problems 58 - 61 and 63 - 65.
Songs played before class:
Red Hot Chili Peppers - Otherside
Billy Currington - That's How Country Boys Roll
Be sure to look over these pages of the lab manual and to read the class notes on this material and I want you to know how to:
1. Given a cation, tell whether it will be included in Group II or Group III based on the experimental conditions in Lab #25.
2. If a cation is in Group III, be able to calculate the pH at which its sulfide will precipitate out of solution.
For #1 you will need to know how to calculate Q and then compare it to the Ksp table and for #2 use the method outlined in class today for Fe2+ for all the other cations. Homework problems 72 - 79 should be a great help in understanding these concepts.
For pretty much the rest of the week we will investigate the following factors that influence solubility:
1. Common Ion Effect
2. pH
3. Complex Ion Formation
4. Amphoterism
I did a calculation in the notes showing the influence of a common ion and we will extend this to discuss pH effects. You MUST know the strong acids and bases and they can be found here. We will use them to identify if the conjugate of a strong acid/base is acidic, basic, or neutral and equipped with that information we can answer questions as to whether certain reagents will increase, decrease, or have no effect on the solubility of certain slightly soluble salts.
I finished the last 5 min of class by discussing which steps you can skip for the Group III analysis with Ni2+, Co2+, and Zn2+. Remember that your unknown will not contain Zn2+ so we can skip quite a few steps. Be sure to look at the conformation tests for Ni2+ and Co2+ and determine a method for how to identify them.
Lastly, Quiz I given at the beginning of lab this week will include all material up to last Friday's lecture (Lecture #3). This material also includes comparing Q vs. K, which is homework problems 58 - 61 and 63 - 65.
Songs played before class:
Red Hot Chili Peppers - Otherside
Billy Currington - That's How Country Boys Roll
Friday, January 8, 2010
Quiz I Study Guide
Quiz I will take place at the beginning of the second laboratory this week. I like to think of the quizzes as a way to determine which students properly understand the concepts in the homework problems and the content of the quiz will solely be based off of the homework set on Carmen and the laboratory exercises (and report question quiz).
Quiz I will be based on the following material:
Lab #24 Exercises and Report Question Quiz
Solubility Homework Set (posted on Carmen)
Questions 1 - 23
Questions 58 - 61 and 63 - 65.
Questions 72 - 79
Also, homework questions 1 - 18 attached to Exp #24 were copied and pasted directly from the Solubility Homework Set (posted on Carmen). The numerical solutions to these questions can be found if you scroll to the bottom of the document.
Quiz I will be based on the following material:
Lab #24 Exercises and Report Question Quiz
Solubility Homework Set (posted on Carmen)
Questions 1 - 23
Questions 58 - 61 and 63 - 65.
Questions 72 - 79
Also, homework questions 1 - 18 attached to Exp #24 were copied and pasted directly from the Solubility Homework Set (posted on Carmen). The numerical solutions to these questions can be found if you scroll to the bottom of the document.
Lecture #3, Friday, January 8th
Today's class started with answering questions about why we need to maintain certain experimental conditions in Group I of Experiment #25. The general procedural details of this experiment are an excellent precursor to the topics we will discuss next week about manipulating solubility. Right now I want you to realize that the temperature, pH, and the concentration of the reagent used can play a big role on how soluble a substance is.
We have been discussing various aspects of solubility, but how can we predict whether a precipitate forms when we add two solutions together? In chemistry 121 the solubility rules were our guide for this, but these guidelines were not very specific about what concentration must be used to facilitate a precipitation reaction. We can selectively separate when various precipitates form by manipulating the concentrations of ions that are mixed together. The reaction quotient, Q, is obtained when concentrations of reactants are inserted into an equilibrium expression. If we are at equilibrium we have a special case of Q that we refer to as K. I performed an example of Q vs. K by analyzing solutions of silver nitrate and potassium chloride.
If you are asked to predict if a precipitate will form you need to calculate Q and compare it to K. In general, if:
Q < K no precipitate forms
Q = K the solution is at equilibrium
Q > K a precipitate will form
We can use this concept to analyze the ions which are contained in Group II and Group III. Over the weekend take a look over pages 51-52 of your lab manual and we will start of lecture on Monday by calculating the pH to determine in a particular ion will be contained in Group II or Group III.
Songs played before class:
Biz Markie - Just a Friend
Run This Town: Jay Z feat. Rihanna and Kanye West
We have been discussing various aspects of solubility, but how can we predict whether a precipitate forms when we add two solutions together? In chemistry 121 the solubility rules were our guide for this, but these guidelines were not very specific about what concentration must be used to facilitate a precipitation reaction. We can selectively separate when various precipitates form by manipulating the concentrations of ions that are mixed together. The reaction quotient, Q, is obtained when concentrations of reactants are inserted into an equilibrium expression. If we are at equilibrium we have a special case of Q that we refer to as K. I performed an example of Q vs. K by analyzing solutions of silver nitrate and potassium chloride.
If you are asked to predict if a precipitate will form you need to calculate Q and compare it to K. In general, if:
Q < K no precipitate forms
Q = K the solution is at equilibrium
Q > K a precipitate will form
We can use this concept to analyze the ions which are contained in Group II and Group III. Over the weekend take a look over pages 51-52 of your lab manual and we will start of lecture on Monday by calculating the pH to determine in a particular ion will be contained in Group II or Group III.
Songs played before class:
Biz Markie - Just a Friend
Run This Town: Jay Z feat. Rihanna and Kanye West
Wednesday, January 6, 2010
Lecture #2, Wednesday, January 6th
Today I discussed Molar Solubility and started class giving you a list of five compounds and asked which one had the largest molar solubility. This is a very common question you will encounter on my quizzes/exams and it will definitely show up on standardized exams such as the MCAT.
Remember that the solubility of a substance is the quantity that dissolves to form a saturated solution, while the the Ksp is the equilibrium constant established and its magnitude can be used to make predictions about solubility. We can directly relate the solubility of compounds with the same ratio of cation:anion, but if two compounds have a different ratio of cation:anion you must perform a calculation using an ICE table in order to predict which compound is more (or less) soluble.
I then introduced Qualitative Analysis. A qual. scheme is designed to answer the question "What is present?" The "Clueless" episode from the second season of the hit TV show House, which premiered on the FOX network on March 28, 2006, has a "real world" application of the qualitative analysis scheme. House was certain that his patient was being poisoned by a heavy metal toxin. His intuition tells him that this toxin is gold and he sets out to prove that he is right.
He heads back to his house and grabs a vial of stannous chloride and after he applies the solution to the suspects hands it turns purple, confirming gold is present.
In Experiment #25 and #26 you get to act as a "detective" in the same manner House did and will need to identify which cations are present in an unknown sample. You will have four lab periods to identify unknowns from Group I, II, and III.
I will do my best to explain the fundamental concepts in this lab and relate them to solubility. For instance, Ag+ and Pb2+ are both contained in group I, but Pb2+ is also present in trace amounts in Group II, but Ag+ never is. The reagent used to isolate the Ag+ and Pb2+ ions from the other cations is cold, dilute HCl. I did a calculation relating the Ksp to the molar solubility then calculated the amount of AgCl and PbCl2 that will dissolve in 4 mL of water.
I will start class on Friday discussing the criteria or the concentrations of each ion needed to form a precipitate in solution. We will then continue with the Group II concepts and factors that influence solubility.
Songs played before class:
Journey: Don't Stop Believing
DJ Earworm: United State of Pop 2009 - Mashup of Top 25 Billboard Hits
Remember that the solubility of a substance is the quantity that dissolves to form a saturated solution, while the the Ksp is the equilibrium constant established and its magnitude can be used to make predictions about solubility. We can directly relate the solubility of compounds with the same ratio of cation:anion, but if two compounds have a different ratio of cation:anion you must perform a calculation using an ICE table in order to predict which compound is more (or less) soluble.
I then introduced Qualitative Analysis. A qual. scheme is designed to answer the question "What is present?" The "Clueless" episode from the second season of the hit TV show House, which premiered on the FOX network on March 28, 2006, has a "real world" application of the qualitative analysis scheme. House was certain that his patient was being poisoned by a heavy metal toxin. His intuition tells him that this toxin is gold and he sets out to prove that he is right.
He heads back to his house and grabs a vial of stannous chloride and after he applies the solution to the suspects hands it turns purple, confirming gold is present.
In Experiment #25 and #26 you get to act as a "detective" in the same manner House did and will need to identify which cations are present in an unknown sample. You will have four lab periods to identify unknowns from Group I, II, and III.
I will do my best to explain the fundamental concepts in this lab and relate them to solubility. For instance, Ag+ and Pb2+ are both contained in group I, but Pb2+ is also present in trace amounts in Group II, but Ag+ never is. The reagent used to isolate the Ag+ and Pb2+ ions from the other cations is cold, dilute HCl. I did a calculation relating the Ksp to the molar solubility then calculated the amount of AgCl and PbCl2 that will dissolve in 4 mL of water.
I will start class on Friday discussing the criteria or the concentrations of each ion needed to form a precipitate in solution. We will then continue with the Group II concepts and factors that influence solubility.
Songs played before class:
Journey: Don't Stop Believing
DJ Earworm: United State of Pop 2009 - Mashup of Top 25 Billboard Hits
Tuesday, January 5, 2010
Exp. #24 Determining a Solubility Product Constant Grading Rubric
This experiment is worth 110 total points and the TA's will grade the report as follows:
10 pts: Lab Notebook
In the lab notebook section you should write out an outline of the procedure (ask your TA what they expect for this section as they are assigning the grade and their styles will vary). You should also write down all numerical results in the lab notebook. You need to sign the bottom of each page and your TA also needs to initial and date each page. Once both of you sign off you will hand your carbon copy sheets to your TA.
25 pts: Completion of Example Problems 1-5
These problems will be graded by your TA on effort, completeness, and neatness. Show all work clearly on a separate sheet of paper (your lab notebook would be perfectly fine or some other sheet).
35 pts: Sample Calculations and data on Report Sheet
A sample calculation from one of your trials must be shown for items 3, 4, 6, and 7 from Part B. of the report sheet. Each calculation is worth 5 points and the calculation for the Ksp is worth 15. These should be written out neatly on a separate sheet labeled Sample Calculations.
40 pts: Report Questions Assessment on Carmen
On Thursday evening I will post a quiz on Carmen titled Experiment #24 Report Questions. It will be due Thursday, January 14th at midnight. These questions, based on the example problems, will be graded on accuracy and you will have 5 attempts for each quiz and your highest score will count towards your lab report grade. Each quiz will have similar problems, but the values for each problem will be slightly different.
All of these sections should be stapled together and your cover page should be the Experiment #25 Report Form and should look like this.
This gives a total of 110 points. The lab report will be due at the beginning of the class on Wed., Jan. 13th or Thurs., Jan. 14th depending on which day you have lab.
Let me know if you have any other further questions. Thanks, Dr. Fus
10 pts: Lab Notebook
In the lab notebook section you should write out an outline of the procedure (ask your TA what they expect for this section as they are assigning the grade and their styles will vary). You should also write down all numerical results in the lab notebook. You need to sign the bottom of each page and your TA also needs to initial and date each page. Once both of you sign off you will hand your carbon copy sheets to your TA.
25 pts: Completion of Example Problems 1-5
These problems will be graded by your TA on effort, completeness, and neatness. Show all work clearly on a separate sheet of paper (your lab notebook would be perfectly fine or some other sheet).
35 pts: Sample Calculations and data on Report Sheet
A sample calculation from one of your trials must be shown for items 3, 4, 6, and 7 from Part B. of the report sheet. Each calculation is worth 5 points and the calculation for the Ksp is worth 15. These should be written out neatly on a separate sheet labeled Sample Calculations.
40 pts: Report Questions Assessment on Carmen
On Thursday evening I will post a quiz on Carmen titled Experiment #24 Report Questions. It will be due Thursday, January 14th at midnight. These questions, based on the example problems, will be graded on accuracy and you will have 5 attempts for each quiz and your highest score will count towards your lab report grade. Each quiz will have similar problems, but the values for each problem will be slightly different.
All of these sections should be stapled together and your cover page should be the Experiment #25 Report Form and should look like this.
This gives a total of 110 points. The lab report will be due at the beginning of the class on Wed., Jan. 13th or Thurs., Jan. 14th depending on which day you have lab.
Let me know if you have any other further questions. Thanks, Dr. Fus
Monday, January 4, 2010
Lecture #1 Course Material and Syllabus Overview and Ksp, January 4th
Today in lecture I went over all the course requirements in the syllabus. I know it may seem like a ton of information all at once, but please be assured that the TA's and I will work with you this quarter and if you ever need anything be sure to ask. Be sure to read over the syllabus and take the COAM quiz on Carmen.
I will try my best to keep this blog updated after every lecture and I will post the materials you will be responsible for on the quizzes and exams on here as well. As always I would appreciate any comments or suggestions as to how to make this resource more valuable to you as a student.
After all the logistical material was covered today in lecture I started on our first "unit," which is SOLUBILITY. Solubility was first introduced to us back in Chapter 4 of the textbook and we were only given a chart of "solubility guidelines" telling us if an ionic substance is "soluble" or "insoluble" in aqueous solution. This table is a way to represent solubility in a qualitative sense, but in this course we will look at solubility in a quantitative sense, or we will determine the exact amount of a substance that dissolves.
To determine just how much solute will dissolve in an aqueous solution, chemists can analyze the equilibrium constant, or Ksp. The Ksp is a measure of how much of a solid dissolves to form a saturated solution.
Typically Ksp tables are generated for various inorganic compounds. The chart listed here is shown in the appendix of the lab manual. There is a relationship between these two tables. Focus a minute on the chlorides in the solubility rules table. All chlorides are soluble with the exception of Ag+, Pb2+, and Hg22+. These are all insoluble, or will form precipitates. All other chlorides will remain in solution. This can now be used as an effective separation technique if we want to isolate Ag+, Pb2+, and Hg22+ from any other cations. This is exactly the case for Ex.p #25 Group I in the qualitative analysis. If you look at the following figure you can now start to see the relationship between these two tables. If a compound is "insoluble," or more accurately, "slightly soluble" there will be a Ksp value associated with it. The smaller the value for the Ksp, the less soluble a substance is. Let me reiterate that the The Ksp is a measure of how much of a solid dissolves to form a saturated solution.
Now lets go back to the Exp. #25 Group I analysis. At the beginning of Lab #2 you will be handed an unknown compound that will consist of one of the three scenarios:
1. Ag+ only
2. Pb2+ only
3. Both Ag+ and Pb2+
What I want you to do is look at the flowchart on the back of the pre-lab or in the lab manual and think of what observations would lead to the confirmation or presence of Ag+, Pb2+, or both. Be sure to have this determined before you come into lab and Group I will not take you very long at all to complete.
Also, keep in mind that Exp. #25 I, II, and III is a long continuation. As soon as you complete Group I you should start right away with Group II. There is a deadline to identify the cations in each of the unknowns for these labs so you do not want to waste any time and the more prepared you are before you step into the lab, the faster the analysis will go.
You should also be starting with Exp. #25 on Lab #2. If you do not finish Lab #24 leave that till the end of the quarter. I will make an announcement in class on Wed. about this as well.
We will discuss how to relate molar solubility to the Ksp and to also calculate how many grams of a substance that will dissolve in a L of soln. We will then look at factors influencing solubility and come up with ways to manipulate the solubility or get something to dissolve that would seemingly be insoluble.
I hope everyone had a great first day of classes and if you need anything from me please let me know. Thanks, Dr. Fus
Songs Before Class:
Bruce Springsteen: Glory Days
Mase: Welcome Back
I will try my best to keep this blog updated after every lecture and I will post the materials you will be responsible for on the quizzes and exams on here as well. As always I would appreciate any comments or suggestions as to how to make this resource more valuable to you as a student.
After all the logistical material was covered today in lecture I started on our first "unit," which is SOLUBILITY. Solubility was first introduced to us back in Chapter 4 of the textbook and we were only given a chart of "solubility guidelines" telling us if an ionic substance is "soluble" or "insoluble" in aqueous solution. This table is a way to represent solubility in a qualitative sense, but in this course we will look at solubility in a quantitative sense, or we will determine the exact amount of a substance that dissolves.
To determine just how much solute will dissolve in an aqueous solution, chemists can analyze the equilibrium constant, or Ksp. The Ksp is a measure of how much of a solid dissolves to form a saturated solution.
Typically Ksp tables are generated for various inorganic compounds. The chart listed here is shown in the appendix of the lab manual. There is a relationship between these two tables. Focus a minute on the chlorides in the solubility rules table. All chlorides are soluble with the exception of Ag+, Pb2+, and Hg22+. These are all insoluble, or will form precipitates. All other chlorides will remain in solution. This can now be used as an effective separation technique if we want to isolate Ag+, Pb2+, and Hg22+ from any other cations. This is exactly the case for Ex.p #25 Group I in the qualitative analysis. If you look at the following figure you can now start to see the relationship between these two tables. If a compound is "insoluble," or more accurately, "slightly soluble" there will be a Ksp value associated with it. The smaller the value for the Ksp, the less soluble a substance is. Let me reiterate that the The Ksp is a measure of how much of a solid dissolves to form a saturated solution.
Now lets go back to the Exp. #25 Group I analysis. At the beginning of Lab #2 you will be handed an unknown compound that will consist of one of the three scenarios:
1. Ag+ only
2. Pb2+ only
3. Both Ag+ and Pb2+
What I want you to do is look at the flowchart on the back of the pre-lab or in the lab manual and think of what observations would lead to the confirmation or presence of Ag+, Pb2+, or both. Be sure to have this determined before you come into lab and Group I will not take you very long at all to complete.
Also, keep in mind that Exp. #25 I, II, and III is a long continuation. As soon as you complete Group I you should start right away with Group II. There is a deadline to identify the cations in each of the unknowns for these labs so you do not want to waste any time and the more prepared you are before you step into the lab, the faster the analysis will go.
You should also be starting with Exp. #25 on Lab #2. If you do not finish Lab #24 leave that till the end of the quarter. I will make an announcement in class on Wed. about this as well.
We will discuss how to relate molar solubility to the Ksp and to also calculate how many grams of a substance that will dissolve in a L of soln. We will then look at factors influencing solubility and come up with ways to manipulate the solubility or get something to dissolve that would seemingly be insoluble.
I hope everyone had a great first day of classes and if you need anything from me please let me know. Thanks, Dr. Fus
Songs Before Class:
Bruce Springsteen: Glory Days
Mase: Welcome Back
Subscribe to:
Posts (Atom)