HELP! Session will be Monday evening, January 28th, beginning at 7:15 pm, in PS110.

Remember to pick up your laoratory experiment before lab this week. You can find it on the Syllabus, or on your Assignment Page (Week 3 lab)

I've been grading problem set #1 questions.

Here are a few comments: On PS1.2 everyone is doing great identifying which substance will have the higher entropy. But nearly everyone has lost 1 point because you are not supporting your choice with sufficient discussion. For example, for a pure substance the gas phase has a higher entropy compared to the liquid phase, because particles in the gas phase are separated by empty space. Particles in a liquid or solid are very close to each other with little or no empty space. So particles in a gas have many more positions that they can occupy so a gas has greater disorder. Similar arguments must be used when comparing two systems and arguing who has the higher entropy.

On PS1.4 be careful about units. Units on entropy are different than units on enthapy or free energy. Also remember it is products minus reactants. Elements have absolute entropy values, and be careful with you math.

On PS1.8a, as in PS1.2 your assignment of the sign of the entropy change must be supported with a comparison of the phases of the reactants and products, and the number of reactant and product particules, you can not just identify the sign and argue the products or reactants are more dissordered, you must support your argument!

LOOK OVER THE ANSWERS POSTED ON THE PROBLEM SET PAGE! VERY IMPORTANT!

On PS2.5 look at ACA4 Q6 as a model as to how to answer a question like PS2.5. It is essential that you discuss BOTH substances when arguing who has the higher boiling point. When you discuss both substances you have to identify the polarity of each molecule, then identify the IMF and then make your argument as to who has the stronger IMF. I have done that in ACA4 Q6.

The During Class Invention and Computer Lab Activities Workbook is now available in the Student Union Bookstore. Looks like it is time to pickup a DCI in class.!

PLE#5 and ACA#5 are now available on your Personal Page. You will need a calculator for both the PLE and ACA.



PS3 is now available on your Personal Page. PS2.1 - PS2.6 (which are the problems that are to be turned in, at the beginning of class, on Thursday, January 24, 2008. PS#3 will is due Tuesday, January 29, 2008.

• With 95% of student responses here are the results of a few of the questions I asked about on the Student Information Form: (Any comments? Send Dr. G an e-mail.)