Thursday, October 21, 2010
Wednesday, October 20, 2010
Exam #1 Locations
Your first Chemistry 123 midterm will be from 8:00 to 9:18pm on Wednesday, October 27th at the following sites:
Room 1008, Evans Lab for Laboratory TA's:
Ally Fry,
Shiladitya Sen &
Siyu Tu;
and
Room 1000, McPherson Lab for Laboratory TA's:
Alex Bernard,
Scott Burya,
Hardy Castada,
Ishika Sinha,
Jennifer Soliz &
Pasco Wambua.
Be sure to work on the Homework Sets and Old Exams.
Room 1008, Evans Lab for Laboratory TA's:
Ally Fry,
Shiladitya Sen &
Siyu Tu;
and
Room 1000, McPherson Lab for Laboratory TA's:
Alex Bernard,
Scott Burya,
Hardy Castada,
Ishika Sinha,
Jennifer Soliz &
Pasco Wambua.
Be sure to work on the Homework Sets and Old Exams.
Lecture #13, Wednesday, October 20th
The transition metal unit was completed today by discussing high spin/low spin complexes with a 4d/5d transition metal center (pg 1037). Since 4d/5d orbitals are larger, the overlap with the ligands is greater, and the crystal field splitting becomes very large. Because of this, we observe low spin electron configurations for complexes with a 4d/5d transition metal center.
The next unit to be discussed is Thermochemistry. I discussed a few general Thermochem topics and started to discuss entropy, which is covered in section 19.2. If you read section 19.2-19.5 before Friday's lecture it will make the information in lecture a little more understandable.
I posted the Thermochem homework set on Carmen.
Inspiration Quote:
"Anything easy ain't worth a damn."
-Woody Hayes
Songs played before class:
Stevie Ray Vaughan - Pride and Joy
Sugarland - Stuck Like Glue
The next unit to be discussed is Thermochemistry. I discussed a few general Thermochem topics and started to discuss entropy, which is covered in section 19.2. If you read section 19.2-19.5 before Friday's lecture it will make the information in lecture a little more understandable.
I posted the Thermochem homework set on Carmen.
Inspiration Quote:
"Anything easy ain't worth a damn."
-Woody Hayes
Songs played before class:
Stevie Ray Vaughan - Pride and Joy
Sugarland - Stuck Like Glue
Tuesday, October 19, 2010
Practice Exams
Several practice exams are posted on Carmen. Be sure to take a look at the study guide indicating which problems to focus on. My best word of advice would be to try and do one practice exam per night from now until the exam.
Lecture #12, Monday, October 18th
For the first time this quarter I used a primarily powerpoint based lecture. This lecture emphasized the key points of molecular orbital theory and showed you the orbital interactions in 3-dimensions. Be sure to be thinking in 3-dimensions when you are visualizing the molecular orbital type concepts. Check out the lecture on Carmen, which is posted in pdf and powerpoint formats.
Inspirational Quote of the Day:
"Promise yourself to think only of the best, to work only for the best, and to expect only the best of yourself and others."
Songs Played Before Class:
Journey - Wheel In The Sky
Oasis - Don't Look Back In Anger
Inspirational Quote of the Day:
"Promise yourself to think only of the best, to work only for the best, and to expect only the best of yourself and others."
Songs Played Before Class:
Journey - Wheel In The Sky
Oasis - Don't Look Back In Anger
Friday, October 15, 2010
Lecture #11, Friday, October 15th
A 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 thehttp://www.blogger.com/img/blank.gif 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 posted a handout on carmen discussing molecular orbitals, bonding, MO diagrams, and color. Be sure to read through it. It will greatly help your understanding of the content. I discussed the molecular orbital diagrams of H2, O2, and an octahedral complex with Cr has the TM center with six oxygen ligands. We will pick up with this content on Monday in lecture.
Be sure to read over the transition metal lab sometime this weekend. I am hoping that it will tie all the concepts we discussed together and you will gain a better understanding of the material. Be sure to try to visualize the 3-Dimensional structures in this lab.
Inspirational Quote:
"It takes less time to do things right than to explain why you did it wrong."
Henry Wadsworth Longfellow
Songs Played Before Class:
Wiz Khalifa - Black And Yellow
Bruce Springsteen - Born To Run
Go Bucks! Beat the Badgers!
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 thehttp://www.blogger.com/img/blank.gif 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 posted a handout on carmen discussing molecular orbitals, bonding, MO diagrams, and color. Be sure to read through it. It will greatly help your understanding of the content. I discussed the molecular orbital diagrams of H2, O2, and an octahedral complex with Cr has the TM center with six oxygen ligands. We will pick up with this content on Monday in lecture.
Be sure to read over the transition metal lab sometime this weekend. I am hoping that it will tie all the concepts we discussed together and you will gain a better understanding of the material. Be sure to try to visualize the 3-Dimensional structures in this lab.
Inspirational Quote:
"It takes less time to do things right than to explain why you did it wrong."
Henry Wadsworth Longfellow
Songs Played Before Class:
Wiz Khalifa - Black And Yellow
Bruce Springsteen - Born To Run
Go Bucks! Beat the Badgers!
Wednesday, October 13, 2010
Quiz #3 Content
Quiz #3 will consist of the transition metal complexes concepts covered in lectures 7-10. To better prepare yourself for the quiz complete the following problems on the ungraded Mastering Chemistry assignment:
Electron Configuration and Oxidation #'s
Coordination Complexes
Isomers/Enantiomers
Naming Coordination Compounds
Problems 24.1 - 24.6
Problems 24.9 - 24.16
Problems 24.17 - 24.20
Problems 24.23 - 24.26
Problems 24.27 - 24.32
Electron Configuration and Oxidation #'s
Coordination Complexes
Isomers/Enantiomers
Naming Coordination Compounds
Problems 24.1 - 24.6
Problems 24.9 - 24.16
Problems 24.17 - 24.20
Problems 24.23 - 24.26
Problems 24.27 - 24.32
Lecture #10, Wednesday, October 13th
As you may have noticed, the transition metal unit is much less mathematical and much more concept/theory based than the solubility unit. To better prepare you for this, be sure to read sections 24.1 - 25.5 of the text book.
Section 24.4 covers isomers, so pay particular attention to Figure 24.17 and know how to differentiate between a structural and geometric isomer and be able to identify coordination-sphere, linkage, geometric, and optical isomers. Sample Exercise 24.6 on page 1029 also gives a pictorial example of optical isomer, so be sure to look that over.
Section 25.5 discusses color. Be sure to look at Figure 24.24 and Figure 24.26 on pages 1032-1033. These figures highlight what was emphasized in class regarding how chemists interpret color of transition metal complexes.
We are finally at the point where we can discuss the reasons we observe different colors in transition metal complexes, and it all boils down to the bonding in transition metal complexes.
On Friday, we will discuss molecular orbital theory in pretty great detail. It would be highly beneficial for you to review the shapes of the orbitals before you come to class. Bonds are formed when atomic orbitals overlap. If you do not know the shapes of the atomic orbitals like the back of your hand then you will not be able to visualize how they interact or overlap.
There is an excellent tutorial that can be found on the OSU department of Chemistry web-site highlighting the shapes of the atomic orbitals.
Pay particular attention to the shapes of the dxy, dxz, dyz, dx2-y2, and dz2 as they will be a focal point of Friday's lecture.
When you view these orbital pictures pay special attention to how the orbitals are oriented in 3-Dimensional space. I mentioned that d orbitals have different energies resulting in fascinating physical properties. The reason the energies are different is due to how the orbitals interact with the ligands. In an octahedral molecule all six ligands fall directly along the cartesian axis, so they will form stronger interactions with orbitals orienting themselves along the x, y, and z axis. We will discuss this further on Friday.
If you want to get ahead read the Orbitals, Bonding, MO Diagrams, and Color "Book Chapter" post under the Content -- Lecture Material section on Carmen.
I also mentioned in class that the report questions for the Qualitative Analysis lab will be due October 21st at 10:00 pm.
Inspirational Quote:
14 (The number of days until the first midterm)
Songs Played Before Class:
Eddie Money : Take Me Home Tonight
Uncle Cracker: Smile
The artist formerly known as Prince: Raspberry Beret
Section 24.4 covers isomers, so pay particular attention to Figure 24.17 and know how to differentiate between a structural and geometric isomer and be able to identify coordination-sphere, linkage, geometric, and optical isomers. Sample Exercise 24.6 on page 1029 also gives a pictorial example of optical isomer, so be sure to look that over.
Section 25.5 discusses color. Be sure to look at Figure 24.24 and Figure 24.26 on pages 1032-1033. These figures highlight what was emphasized in class regarding how chemists interpret color of transition metal complexes.
We are finally at the point where we can discuss the reasons we observe different colors in transition metal complexes, and it all boils down to the bonding in transition metal complexes.
On Friday, we will discuss molecular orbital theory in pretty great detail. It would be highly beneficial for you to review the shapes of the orbitals before you come to class. Bonds are formed when atomic orbitals overlap. If you do not know the shapes of the atomic orbitals like the back of your hand then you will not be able to visualize how they interact or overlap.
There is an excellent tutorial that can be found on the OSU department of Chemistry web-site highlighting the shapes of the atomic orbitals.
Pay particular attention to the shapes of the dxy, dxz, dyz, dx2-y2, and dz2 as they will be a focal point of Friday's lecture.
When you view these orbital pictures pay special attention to how the orbitals are oriented in 3-Dimensional space. I mentioned that d orbitals have different energies resulting in fascinating physical properties. The reason the energies are different is due to how the orbitals interact with the ligands. In an octahedral molecule all six ligands fall directly along the cartesian axis, so they will form stronger interactions with orbitals orienting themselves along the x, y, and z axis. We will discuss this further on Friday.
If you want to get ahead read the Orbitals, Bonding, MO Diagrams, and Color "Book Chapter" post under the Content -- Lecture Material section on Carmen.
I also mentioned in class that the report questions for the Qualitative Analysis lab will be due October 21st at 10:00 pm.
Inspirational Quote:
14 (The number of days until the first midterm)
Songs Played Before Class:
Eddie Money : Take Me Home Tonight
Uncle Cracker: Smile
The artist formerly known as Prince: Raspberry Beret
Monday, October 11, 2010
Lecture #9, Monday, October 11th
Today we continued to discuss transition metal complexes by determining the oxidation state, coordination number, and geometry of various coordination complexes. We went over the observed geometries and discussed when one geometry would be preferred over another.
Then we went on to talk about nomenclature. Nomenclature of transition metal complexes might be one of the most boring lectures to give (if you have any tips on how to make it more exciting please let me know), and the way in which these complexes are names is pretty bizarre, but you need to know how to name them. I posted the rules on how to name transition metal complexes up on Carmen and they are also included in the lab manual. Part of your lab next week will include nomenclature.
I also emphasized the term ligand. There are two tables in the text: Table 24.3 on page 1019 and Table 24.3 on page 1025, indicating which ligands you will be responsible for on a quiz or exam. Be sure to look those over and if you are keeping up with the material, you should have read Sections 24.1, 24.2, 24.3 and 24.4 by class on Wednesday. I briefly discussed isomers at the end of the class period and will pick up with them on Wednesday.
Inspiration Quote:
"If the game of life ended tonight, would you be a winner?"
-Jim Tressel
Songs Played Before Class:
Taio Cruz - Dynamite
Guns n' Roses - Sweet Child O' Mine
Then we went on to talk about nomenclature. Nomenclature of transition metal complexes might be one of the most boring lectures to give (if you have any tips on how to make it more exciting please let me know), and the way in which these complexes are names is pretty bizarre, but you need to know how to name them. I posted the rules on how to name transition metal complexes up on Carmen and they are also included in the lab manual. Part of your lab next week will include nomenclature.
I also emphasized the term ligand. There are two tables in the text: Table 24.3 on page 1019 and Table 24.3 on page 1025, indicating which ligands you will be responsible for on a quiz or exam. Be sure to look those over and if you are keeping up with the material, you should have read Sections 24.1, 24.2, 24.3 and 24.4 by class on Wednesday. I briefly discussed isomers at the end of the class period and will pick up with them on Wednesday.
Inspiration Quote:
"If the game of life ended tonight, would you be a winner?"
-Jim Tressel
Songs Played Before Class:
Taio Cruz - Dynamite
Guns n' Roses - Sweet Child O' Mine
Lecture #8, Friday, October 8th
Transition metal complexes fascinated chemists back to the early ages due to their color. In the transition metal unit we will talk about the bonding theories chemists use to explain the differences in color for the observed transition metal complexes.
Remember that for our eyes to observe color, an electronic transition must be in the visible region of the electromagnetic spectrum. A transition occurs when an electron is excited from the ground state (an orbital of lowest energy containing an electron) to an excited state (an orbital of higher energy that is empty). In order to understand the reason behind the color in these complexes always keep two things in the back of your mind: #1 How many d electrons does a transition metal ion possess, and #2 What is the energy of the orbitals containing the electrons (or more importantly, what is the energy difference between the empty orbitals).
Before we get into the meat and potatoes of transition metal chemistry, and more exciting bonding theories (humor me, I'm a big dork and this stuff is pretty neat to me), we need to discuss some background information on transition metal complexes.
I went over how to properly determine the electron configuration of a transition metal cation. Be sure you are able to do this. We then reviewed the electromagnetic spectrum and I mentioned how unique it is to observe excitations in the visible spectrum since the energy of the visible spectrum takes up such a tiny portion of the visible spectrum.
We then discussed coordination compounds and the early work of Alfred Werner. This led to our modern day notation of transition metal complexes and the term isomer.
Inspiration Quote:
"If you don't have time to do it right, when will you have time to do it over?"
-John Wooden
Songs Played Before Class:
Sum 41 - In Too Deep
Brad Paisley - Water
Remember that for our eyes to observe color, an electronic transition must be in the visible region of the electromagnetic spectrum. A transition occurs when an electron is excited from the ground state (an orbital of lowest energy containing an electron) to an excited state (an orbital of higher energy that is empty). In order to understand the reason behind the color in these complexes always keep two things in the back of your mind: #1 How many d electrons does a transition metal ion possess, and #2 What is the energy of the orbitals containing the electrons (or more importantly, what is the energy difference between the empty orbitals).
Before we get into the meat and potatoes of transition metal chemistry, and more exciting bonding theories (humor me, I'm a big dork and this stuff is pretty neat to me), we need to discuss some background information on transition metal complexes.
I went over how to properly determine the electron configuration of a transition metal cation. Be sure you are able to do this. We then reviewed the electromagnetic spectrum and I mentioned how unique it is to observe excitations in the visible spectrum since the energy of the visible spectrum takes up such a tiny portion of the visible spectrum.
We then discussed coordination compounds and the early work of Alfred Werner. This led to our modern day notation of transition metal complexes and the term isomer.
Inspiration Quote:
"If you don't have time to do it right, when will you have time to do it over?"
-John Wooden
Songs Played Before Class:
Sum 41 - In Too Deep
Brad Paisley - Water
Wednesday, October 6, 2010
Quiz #2 Content
Everything on the Solubility homework set posted on Carmen is fair game. I would focus on the following questions...
*33-46
*47-57
*58-71
*72-79
*Questions 1, 2, and 4 from the Qualitative Analysis Lab
*33-46
*47-57
*58-71
*72-79
*Questions 1, 2, and 4 from the Qualitative Analysis Lab
Lecture #7, Wednesday, October 6th
Today I finished the solubility unit by discussing the Group II/Group III selective precipitation by analyzing the pH at which the sulfides precipitate out in solution. The Group II cations precipitate at a low pH, while the Group III cations precipitate out at a higher pH. I performed an example for FeS(s) and the pH at which every other cation in Group II and Group III can be calculated in a similar fashion (see questions 77-79 on the solubility work on Carmen).
The last type of problem I covered in the solubility unit was a problem asking about the order in which precipitate drop out of solution when a precipitating agent is added slowly (or dropwise) to a solution containing more than one cation/anion. This will allow you to complete questions 64-71 on the Carmen homework set.
I started to briefly cover the transition metal unit by looking at the oxidation states and d electron counts of transition metal complexes. If you are rusty in electron configurations be sure to look them over, as they will be vital in understanding transition metal complexes.
Songs Played Before Class:
Counting Crows - Mr. Jones
Eminem feat Rihanna - Love the way you lie
Inspiration Quote of the Day:
“I don’t want to come home and look in the mirror and think the reason I didn’t do well was because I didn’t prepare.”
2008 World Series Champion Chase Utley
Go Phillies!
The last type of problem I covered in the solubility unit was a problem asking about the order in which precipitate drop out of solution when a precipitating agent is added slowly (or dropwise) to a solution containing more than one cation/anion. This will allow you to complete questions 64-71 on the Carmen homework set.
I started to briefly cover the transition metal unit by looking at the oxidation states and d electron counts of transition metal complexes. If you are rusty in electron configurations be sure to look them over, as they will be vital in understanding transition metal complexes.
Songs Played Before Class:
Counting Crows - Mr. Jones
Eminem feat Rihanna - Love the way you lie
Inspiration Quote of the Day:
“I don’t want to come home and look in the mirror and think the reason I didn’t do well was because I didn’t prepare.”
2008 World Series Champion Chase Utley
Go Phillies!
Monday, October 4, 2010
Ksp Formal Lab Report
The formal lab report for the Ksp lab is due Wed/Thurs this week depending on which day you have lab. In general, lab reports are due one week after you complete the lab. I have been receiving several questions about what to include so here is what I expect for this lab report.
First go to Carmen and look at the Ksp formal lab report guidelines and the Ksp formal lab report grading rubric. The details for what to include in the report are listed there.
Some other words of wisdom for the report:
*It must be typed
*It will be very helpful to get a 123 TA to look over your report. There is a 123 TA present in 160 CE pretty much all day on Tuesdays. They will be your best resource for editing and giving helpful hints for the report because they will be the ones grading it.
*The Report sheet should be attached and all you need to say is something like "The results are displayed on the attached report sheet." In the discussion you need to look up (and be sure to cite your source) the Ksp and compare that to your experimental Ksp. The "critical thinking question" is to properly discuss the error. What I mean by this is to come up with a chemical reason (it is really beneficial to discuss the overall equilibrium expression and what cause this equilibrium to shift to the left or the right) your value is different than the literature value.
*Sometimes students think they can perform 3 trials in the lab and simply give an average Ksp. Whenever you calculate an average value in the lab, you must report a standard deviation (or some sort of error analysis with it). On page 1110 of your textbook it shows how to calculate the standard deviation. Your "reported Ksp for Ca(IO3)2" is your experimental average for the Ksp +/- the standard deviation.
First go to Carmen and look at the Ksp formal lab report guidelines and the Ksp formal lab report grading rubric. The details for what to include in the report are listed there.
Some other words of wisdom for the report:
*It must be typed
*It will be very helpful to get a 123 TA to look over your report. There is a 123 TA present in 160 CE pretty much all day on Tuesdays. They will be your best resource for editing and giving helpful hints for the report because they will be the ones grading it.
*The Report sheet should be attached and all you need to say is something like "The results are displayed on the attached report sheet." In the discussion you need to look up (and be sure to cite your source) the Ksp and compare that to your experimental Ksp. The "critical thinking question" is to properly discuss the error. What I mean by this is to come up with a chemical reason (it is really beneficial to discuss the overall equilibrium expression and what cause this equilibrium to shift to the left or the right) your value is different than the literature value.
*Sometimes students think they can perform 3 trials in the lab and simply give an average Ksp. Whenever you calculate an average value in the lab, you must report a standard deviation (or some sort of error analysis with it). On page 1110 of your textbook it shows how to calculate the standard deviation. Your "reported Ksp for Ca(IO3)2" is your experimental average for the Ksp +/- the standard deviation.
Life Sciences and Physical Sciences Career Fair
Tuesday, October 5th, 2010 10:30 am - 3:30 pm The Ohio Union Performance Space
An outline of the event and all the employers present can be found at this link.
This could be a great opportunity to gain information on internships and a future job. Be sure to check it out if you can.
An outline of the event and all the employers present can be found at this link.
This could be a great opportunity to gain information on internships and a future job. Be sure to check it out if you can.
Lecture #6, Monday, October 4th
Today we nearly completed the solubility unit of the course by wrapping up complex ion formation and amphoterism. Using the examples covered in class you should be able to perform problems 34-46 from the Carmen homework set. Be sure to do these problems over and over and over again, until you have a firm grasp of the underlying concepts in each of these problems.
Now that we have discussed all the effects of solubility, questions 47-55 can be answered. In each of these problems be sure to start by writing out the equilibrium expression and decide what effect each reagent has on the concentrations of the ions in solution. By changing the concentration of either ion in solution, the solubility will change. Be sure to keep in mind complex ion formation and amphoteric effects. A complex ion will form if there is a reported Kf value associated with the transition metal cation and its ligands.
At the end of lecture I discussed the Group II/Group III separation and we will discuss the solubility of metal sulfides and the Group III separations on Wed. Be sure you read through your lab manual to get a more in depth analysis of all the reactions that occur in aqueous solution in the qualitative analysis scheme.
Inspiration Quote of the Day:
"Most all good things come through adversity.
Looking back it seems to me,
All the grief that had to be
Left me when the pain was o’er
Stronger than I was before.
- Unknown
We get stronger when we test ourselves. Adversity can make us better. We must challenge to improve, and adversity is the challenger."
Songs Played Before Class
blink-182 - Man Overboard
Journey - Don't Stop Believing
Kappa Dog Night Information
Kappa Dog Night is semi-annual fundraiser hosted by the women of Kappa Kappa Gamma. Between the hours of 12:00am and 3:00am we invite fellow students to join us in raising money for Kappa Kidney Camp, a juvenile camp for those affected by kidney disease. Hot dogs and soda will be sold for $1.50. There will be a HOT DOG EATING contest again this year. It is $10 to participate and the person to eat the most hot dogs in 2 minutes will be named this year's "Kappa Dog Man"! The contest will take place at 1:30am, so come out and cheer on the contestants! We look forward to seeing you all on Thursday!
Now that we have discussed all the effects of solubility, questions 47-55 can be answered. In each of these problems be sure to start by writing out the equilibrium expression and decide what effect each reagent has on the concentrations of the ions in solution. By changing the concentration of either ion in solution, the solubility will change. Be sure to keep in mind complex ion formation and amphoteric effects. A complex ion will form if there is a reported Kf value associated with the transition metal cation and its ligands.
At the end of lecture I discussed the Group II/Group III separation and we will discuss the solubility of metal sulfides and the Group III separations on Wed. Be sure you read through your lab manual to get a more in depth analysis of all the reactions that occur in aqueous solution in the qualitative analysis scheme.
Inspiration Quote of the Day:
"Most all good things come through adversity.
Looking back it seems to me,
All the grief that had to be
Left me when the pain was o’er
Stronger than I was before.
- Unknown
We get stronger when we test ourselves. Adversity can make us better. We must challenge to improve, and adversity is the challenger."
Songs Played Before Class
blink-182 - Man Overboard
Journey - Don't Stop Believing
Kappa Dog Night Information
Kappa Dog Night is semi-annual fundraiser hosted by the women of Kappa Kappa Gamma. Between the hours of 12:00am and 3:00am we invite fellow students to join us in raising money for Kappa Kidney Camp, a juvenile camp for those affected by kidney disease. Hot dogs and soda will be sold for $1.50. There will be a HOT DOG EATING contest again this year. It is $10 to participate and the person to eat the most hot dogs in 2 minutes will be named this year's "Kappa Dog Man"! The contest will take place at 1:30am, so come out and cheer on the contestants! We look forward to seeing you all on Thursday!
Friday, October 1, 2010
Lecture #5, Friday, October 1st
We continued to discuss solubility by analyzing the effect pH has on solubility. Acids and bases neutralize each other and in the process the concentration of [H+] and [OH-] will either increase or decrease causing the equilibrium to shift. A shift in this equilibrium influences the solubility.
In order for an acid to neutralize a base or for a base to neutralize an acid, a species in the solution must be either acidic or basic. After writing out the equilibrium expression for the slightly soluble salt of interest, we need to determine if the cations/anions in solution are acidic or basic.
The conjugate acid of a weak base is considered to be acidic.
The conjugate base of a weak acid is considered to be basic.
The conjugate acid of a strong base is considered to be neutral.
The conjugate base of a strong acid is considered to be neutral.
In order to determine if the cation/anion of interest is acidic or basic, you need to be able to rattle off all of the strong acids and strong bases off the top of your head.
Strong Acids: HCl, HBr, HI, HClO3, HClO4, HNO3, and H2SO4.
Strong Bases: LiOH, NaOH, KOH, RbOH, CsOH, Ca(OH)2, Sr(OH)2, Ba(OH)2
I went through a few examples of how varying the pH can influence the solubility. Be sure to write out your solubility equilibrium expression as the first step to each problem.
We found that 8.27 x 10-7 grams of Fe(OH)2 will dissolve in 4 mL of water at a pH = 7, but when a solution is buffered to a pH = 6, the solubility dramatically increases to 0.175 grams in 4 mL.
Based on what we discussed up to this point, when we add a base, such as ammonia, to Zn(OH)2 we would expect its solubility to decrease. But experimentally we find that when concentrated ammonia is added the solubility increases. We now need to come up with a reason for why this happens. Chemists in the early 1900's were able to determine this increase in solubility was due to complex ion formation.
A complex ion contains a central metal ion surrounded by a number of ligands which are held together by coordinate covalent bonds. A ligand is a surrounding anion or molecule containing an unshared pair of electrons. Common ligands are NH3, Cl-, H2O, OH- among others
An example problem was performed showing how the formation of the Zn(NH3)42+ increases the solubility of Zn(OH)2.
On Monday we will pick up with this example and discuss a special case of the effect of complex ion formation referred to as amphoterism.
Quote of the Day:
"Failure to change is often just stubbornness that comes from an unwillingness to learn, an inability to realize you’re not perfect. There cannot be progress without change – even though not all change is progress."
Songs Played Before Class:
Tom Petty- Free Falling
Kenney Chesney - This is Our Time
In order for an acid to neutralize a base or for a base to neutralize an acid, a species in the solution must be either acidic or basic. After writing out the equilibrium expression for the slightly soluble salt of interest, we need to determine if the cations/anions in solution are acidic or basic.
The conjugate acid of a weak base is considered to be acidic.
The conjugate base of a weak acid is considered to be basic.
The conjugate acid of a strong base is considered to be neutral.
The conjugate base of a strong acid is considered to be neutral.
In order to determine if the cation/anion of interest is acidic or basic, you need to be able to rattle off all of the strong acids and strong bases off the top of your head.
Strong Acids: HCl, HBr, HI, HClO3, HClO4, HNO3, and H2SO4.
Strong Bases: LiOH, NaOH, KOH, RbOH, CsOH, Ca(OH)2, Sr(OH)2, Ba(OH)2
I went through a few examples of how varying the pH can influence the solubility. Be sure to write out your solubility equilibrium expression as the first step to each problem.
We found that 8.27 x 10-7 grams of Fe(OH)2 will dissolve in 4 mL of water at a pH = 7, but when a solution is buffered to a pH = 6, the solubility dramatically increases to 0.175 grams in 4 mL.
Based on what we discussed up to this point, when we add a base, such as ammonia, to Zn(OH)2 we would expect its solubility to decrease. But experimentally we find that when concentrated ammonia is added the solubility increases. We now need to come up with a reason for why this happens. Chemists in the early 1900's were able to determine this increase in solubility was due to complex ion formation.
A complex ion contains a central metal ion surrounded by a number of ligands which are held together by coordinate covalent bonds. A ligand is a surrounding anion or molecule containing an unshared pair of electrons. Common ligands are NH3, Cl-, H2O, OH- among others
An example problem was performed showing how the formation of the Zn(NH3)42+ increases the solubility of Zn(OH)2.
On Monday we will pick up with this example and discuss a special case of the effect of complex ion formation referred to as amphoterism.
Quote of the Day:
"Failure to change is often just stubbornness that comes from an unwillingness to learn, an inability to realize you’re not perfect. There cannot be progress without change – even though not all change is progress."
Songs Played Before Class:
Tom Petty- Free Falling
Kenney Chesney - This is Our Time
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