Wednesday, September 29, 2010

Quiz #1 Content

The following content is fair game for Quiz #1. I would highly suggest working out these problems before you attempt the quiz:

*Every topic covered in lecture up to and including the Common Ion Effect

*Material from the "Developing a Mastery of the Solubility Product Constant Lab"

*Problems 1-27 and 58-63 from the Homework Set posted on Carmen

*The Ungraded Practice Ksp practice problems on Mastering Chemistry

Lecture #4, Wednesday, September 29th

In the "Clueless" episode of House, Dr. House was able to prove one of his patients was being poisoned by his fiance by using a confirmation reagent. And similar to a qualitative analysis scheme, he was able to identify that gold was present on a person's hands. Similarly, chemists use a qualitative analysis scheme to identify which ions are present in a solution.

In lab next week you will be given a solution containing Ag+, Pb2+, Cu2+, Ni2+, Al3+, and Bi3+/5+. You will need to follow a scheme outlined in the manual and design your own procedure that will allow you to determine which ions are present in an unknown solution. You will have 3 lab periods to experiment and in the 4th lab period you will be given your unknown to identify.

The scheme we use to identify the ions utilizes differences in solubility and we classify the ions into groups based on their solubility. I outlined the Group I separation, which precipitates out AgCl and PbCl2.

The separations of the ions we will analyze depend on four main effects:

1. Common Ion
2. pH
3. Complex Ion Formation
4. Ampoterism

I discussed the Common Ion Effect today, as it follows Le Chatlier's Principle. I performed a few calculations illustrating the dramatic effect the Common Ion effect can have on solubility.

We will continue with pH effects on Friday and it would be good to look over the strong acids and strong bases, because you will need to know them off the top of your head.

Quote of the Day:
"Why is it so difficult to motivate ourselves when we know that results come only through motivation?'

Songs Played Before Class:
Nelly - Just A Dream
The Killers - All These Things That I've Done

Monday, September 27, 2010

Lecture #3, Monday, September 27th

Today I started off by quickly reviewing the example problem given at the end of lecture on Friday and then looked at the Ksp of Cadmium Hydroxide and discussed why we might see different reported Ksp for this substance.

We then skipped ahead to Section 17.6 in the text, which allows us to calculate if a precipitate will form when two (or more) solutions of known concentrations are added together. I performed two examples based on this concept and chemists can use these principles to separate or remove a desired ion from a solution containing many other ions.

We can selectively separate ions in solution by manipulating the concentrations of precipitating agents 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

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 spend three lab periods analyzing the known solution and you will have one lab period to identify unknown cations present in your sample. The sole part of your grade will depend on if you properly identify the ions in your unknown solution.

I will do my best to explain the fundamental concepts in this lab and relate them to solubility.

If you are keeping up with the material so far you should be able to complete problems 1-18 and 58-63 on the homework set posted on Carmen. I would encourage you to work out the problems first without looking at the worked out solutions, then checking the key to be sure your work is complete.

Today's inspirational quote was submitted by Dina Yacoub
"Take the first step in faith. You don't have to see the whole staircase, just take the first step."
Martin Luther King, Jr.

Song Played Before Class:
Kanye West ft. Dwele - Power

Practice Mastering Chemistry Assignments

To access the ungraded optional assignments on Mastering Chemistry, click on the assignments tab and a window should open up and look like this.

I would highly suggest that you start working on these problems before the quiz on Friday and before the Ksp lab report questions. Be sure to utilize the tutorial problems and use the hints if you are struggling to find the correct answers.

Sunday, September 26, 2010

Lecture #2, Friday, September 24th

Lab #2 "Developing a Mastery of the Solubility Product Constant," introduces an experimental way to determine the Ksp for Ca(IO3)2. Remember that chemistry is an experimental science where measurements are made. The Ksp Tables you see in the textbook have been crafted from experimental data, and proper interpretation of these values can tell a chemist a great deal about solubility.

Experimentally we can consider solubility equilibria to make predictions about the amount of a given compound that will dissolve. As we progress through the solubility unit we will then discuss various ways to manipulate the solubility of various salts.

Be sure to have a grasp of what an equilibrium constant tells you. A large value for k favors the products, and a small value of k favors reactants. If you have the experimental value for the Ksp you can calculate the molar solubility for a slightly soluble salt. I ended class with several calculations of how to determine the molar solubility of a list of slightly soluble salts and will sontinue with that discussion on Monday.

Today's inspirational quote was submitted by Erin Riley
“We are what we repeatedly do. Excellence, therefore, is not an act, but a habit."
-Aristotle

Songs Played Before Class
Bruce Springsteen - Glory Days
Mase - Welcome Back

Thursday, September 23, 2010

Mastering Chemistry Registration

Be sure to register for Mastering Chemistry ASAP. Your first assignment is due Monday morning at 8:30 am and we currently have 151 out of 225 students signed up. If you click the following link it will give you all the information you need to properly login.

Wednesday, September 22, 2010

Welcome Back!

To all the returning students welcome back! And to all the freshman welcome to campus. It is great to see the halls full of bright young minds eager to learn. I'll kick of the quarter with a quote from President Gee's address to the incoming freshman.

"Make the most of this time; it will not come again … make each day count. This is the place to expand your horizons to any and all opportunities.”

E. Gordon Gee

I'd also like to post an inspirational quote each day before class starts, so please e-mail any of your favorites.