
Photo by Milosz1
Since it has been discussed somewhat in comments (i.e. mentioned twice) it is probably best to move right on into Gen Chem II. Where Gen Chem I was an introduction into Chemistry itself, Gen Chem II is more like a survey of advanced topics in chemistry. Several of the topics introduced in Gen Chem I are discussed in greater detail. A few new topics are introduced.
To start off, the class will cap off the discussion on the properties of the states of matter by continuing on to liquids and solids (Note: This is where my semester broke into Chem I and II. Your experience may vary). Liquids behave much differently than gases, so this won’t be a continuation of the section on gases from last semester. This section will cover basic properties of liquids. One example of this is the Clausius-Clapeyron equation for expressing vapor pressure mentioned in the comments from the last post. For solids, we actually just briefly talked about ionic and network covalent formations. Solids stay still and are pretty boring that way.
The next few sections will be based heavily on (but not limited to) aqueous solutions. A more in-depth look into the different types of solutions will start off this group of chapters. This will be followed by sections on kinetics (reaction rates) and dynamic equilibrium (how far a reaction goes). After that, there will be a few sections on quantifying solubility and pH, describing weak solutions as dynamic equilibria and describing some acids and bases as well as water itself as weak solutions. This last bit with the acids and bases is where Henderson–Hasselbalch comes into play describing the pH and pKa of weak acids and bases.
The last two chapters that we covered in my class are a natural stopping point in most books. They are required to understand things in future classwork…even if much further down the line. The first of these continued the earlier lessons on thermodynamics. Even if a reaction gives off heat energy, it may not necessarily be a spontaneous reaction. This is where an understanding of the second law of thermodynamics must take place for the chemistry student. Because our universe tends to move towards randomness, there is a difference between the heat energy that gets released from a reaction and the free energy that we can use from it. In the poker game of life, entropy is the rake.
The chapter after that uses these concepts from thermodynamics and introduces the concept of reduction potential to introduce electrochemistry. If you take a given reduction/oxidation reaction, one side of the reaction must want to be reduced more than the other for the reaction to be spontaneous. If that happens, then electron exchange takes place between the reduction and oxidation sides of the reaction. If you are very good at this, you can use this reduction potential by passing a reduction/oxidation reaction over conductive wires and running your iPod on it.
It also dawns on me that I haven’t talked about reduction and oxidation reactions, which can be a sticking point. Reduction/oxidation reactions are coupled chemical reactions by nature of moving electrons from one atom or molecule to another. Reduction is the gaining of electrons and oxidation is the loss of electrons. This throws people a little since reduction means gaining something, but in actuality you are reducing the charge of something. If you reduce oxygen to water, the charge on the oxygen atom goes from zero (0) to negative two (-2). Oxidation is named so because adding oxygen will generally increase the charge on an atom because oxygen is always negative. Carbon dioxide is carbon in a very oxidized state. An easier way to remember this is that LEO the lion says GER. LEO - Loosing Electrons, Oxidation; GER - Gaining Electrons, Reduction.
There are also some mnemonics for the reduction/oxidation and cation/anion, but I can’t remember them and there are some differences with different types of electric cells (depending on whether you are using the reaction or driving it). Best just to learn this straight up.
The class will probably end before you get to the end of the book. The uncovered chapters still hold some important information though. If you are taking any kind of standardized test covering this material (e.g. the AP exam, the ACS exam) you should flip through the first part of the chapter on Nuclear Chemistry. Understanding how the reactions work and knowing the notations used in writing nuclear reactions will help. They are just like regular chemical reactions except the atoms can change from element to element by gaining or loosing special particles; matter is conserved at the subatomic level…mostly. Be able to identify alpha and beta particles as well as fission and fusion reactions. No test should ask you anything beyond that. The first part of the organic chemistry chapter should also be reviewed before the AP exam, and the whole thing is a great introduction into your organic class and any petrochemistry you might come across. My book also had a separate biochem chapter which might be good to look at for a biochem class…except your organic book will probably have a better biochem chapter.
There were also chapters in my book (I would imagine these all vary) on the different groups of elements that I never had the time or the need to review and a chapter on complex ions and coordination compounds which I flipped through when writing my lab report on complex ions and coordination compounds. You will probably never crack to book open to any point in these chapters, ever.
This class involved much more complex math than Gen Chem I. If you weren’t honing your study skills during Gen Chem I, then now is the time to start. The conceptual stuff is much more complex here and there isn’t a lot of room for error in the packed syllabus. My Gen Chem II lab was part of this course and counted towards the overall grade (like Gen Chem I). The lab had less one-off labs in lieu of a larger project which involved producing a compound and then using quantitative techniques to figure out the chemical formula for the compound. Do all your homework, keep ahead on your notes/flashcards, study for the tests and don’t get behind on the lab work.
Next I think we’ll be talking about Gen Bio, but I may take a break on the prereqs posts for a little before then.
Chemistry Picture: http://www.flickr.com/photos/mikolski/ / CC BY 2.0