Dec. 15th- Entropy, Enthalpy, and much more

We're back! Since the start of the 2nd Trimester, we have been learning many new and intriguing concepts. We started off learning a little bit about Thermochemistry and Bond Enthalpies. We learned about the four ways to calculate a certain bond enthalpy and whether these processes are endothermic or exothermic. We then learned all about bond entropy and Gibbs Free Energy. Along the way, we learned about Aqueous solutions and Precipitation reactions also.

The first thing we learned about in trimester 2 was the concepts of thermochemistry and bond enthalpies. We learned that enthalpy is practically the heat lost or gained in the system as seen below.
When the change in enthalpy is positive, the process is endothermic as opposed to negative change identifying with the process as exothermic. We also learned four methods to find the change in enthalpy. These four ways were discussed very in depth over a serious of Lectures and Lecture Quizzes. The formula using average bond energies was simply the (positive) Total Bonds Broken plus the (negative) Total Bonds formed. The res of the formulas can be found with their correlating Power Points at the links below.

Calorimetry Formula
Hess's Law and Enthalpies of Formation

We then went on to learn that entropy is a measure of the most probable distinguishable microstates or degrees of freedom available to a system. To calculate the change in entropy, you simply find the sum f products minus the sum of the reactants with stoichiometric standard entropies. We also found out how to find whether a reaction was spontaneous of not by the table below. The formula for Gibbs Free Energy can also be seen below.

We then went on to learn about Precipitation reactions and Net Ionic equations. To find these Net Ionic equations, you basically find the elements that are soluble in water and take them out of the equation leaving only the reactants that are insoluble in water. Some soluble compound include Na+, K+, NH4+, and NO3+.

Overall, we learned a lot of new concepts and important information on Entropy and Enthalpy over the past few weeks. I still have a few unanswered questions regarding both concepts but once I prepare for the Friday test by reviewing the Power Points, I'm sure the information will become much more clear. My participation in class these past few weeks have not been very good at all and is something I really need to work on moving forward. On a scale of 1-5, I would rate my understanding at a 3 of the information we've learned over the past few weeks. I need to study pretty hard this week in order to be prepared for the test. Once I review these basic concepts, the test should be a piece of cake!