Time to get this blog updated!

Wow, there has been a great deal of material covered since the last blog. So let me catch you up on the Thermochemsitry material.

After a brief introduction of thermodynamics, I discussed what thermodynamics can and can't tell us about a reaction mechanism, and then introduced entropy. We discussed the second law of thermodynamics and I gave some guidelines for the entropy of the universe. We can also associate numerical values with entropy and the third law of thermodynamics allows us to do so by defining the entropy of a pure crystal at 0 K. I also performed an example very similar to what we saw in chapter 5, where we had to calculate the standard entropy of a reaction, which is the exact same method used to calculate the standard enthalpy of a reaction.

In the last 5 minutes I put the Gibbs Free Energy equation on the board because you will need it in lab this week.

The last section of the Thermochemistry lecture's focused mainly on Gibbs Free Energy, which is sections 19.5, 19.6, and 19.7 of the textbook. I would read all three of these sections of the text, and after reading those sections, you should have no problem in completing all of the Thermodynamics homework set.

I began the next class by discussing some issues we had in the lab in calculating K_sp. One main idea that I want to emphasize to everyone in this class is to "Think like a chemist." Don't simply go through the motions and calculate numbers in the lab. These numbers have meaning and I want you to see the underlying meaning behind them. Chemistry can be so frustrating because students rarely appreciate where the numbers and formulas come from. I want you to see how everything relates together. The solubility chapter overlaps so much with the Thermochem chapter and has many applications in the transition metal unit.

The numerical results of the Thermodynamics lab were discussed. I gave a powerpoint presentation, which is posted on Carmen. Remember that chemistry is an experimental science and all the theories and equations were developed from experimental data. Today we discussed why the value we obtained for the entropy change for a process in which a slightly soluble salt dissolved was negative. We also analyzed why the same reaction had a negative enthalpy change.

We finished the Thermochem unit by discussing the "Chelate Effect," which takes experimental values obtained in the synthesis of transition metal complexes and relates them to the overall entropy of a particular reaction. This effect is seen in cases where polydentate ligands replace monodentate ligands in transition metal complexes. The "A Closer Look" box on pages 1021-1022 describes this theory into more detail.

The next unit we will discuss is electrochemistry. Electrochemists study and try to manipulate the flow of electrons. This is seen in almost every practical material involving electricity. The main principle I want everyone to keep in the back of their minds is: How can a chemist manipulate the flow of electrons. Once we understand this concept we can then go on to bigger and better problems such as assembling a battery or electrochemical cell to power anything from an electronic device to an automobile.

The electrochemistry lectures focussed on the principles related to the lab and Chapter 20 of the textbook. Thus far, we have covered the content from Sections 20.1 - 20.6 in the textbook. I will finish up this unit soon with section 20.9, which is titled electrolysis and this is the content of the second electrochemistry lab period.

For the time being we will skip over section 20.7, which is batteries and fuel cells, but in our energy unit we will come back to it. The next unit will focus on energy and many of the electrochemical principles will resurface.