This week was entirely about gases, ideal and real. Ideal gases don't actually exist, but they follow the kinetic molecular theory, which is a model of what happens to gas particles as conditions change. Kinetic molecular theory has a couple of main tenets. According to KMT, gases consist of large numbers of molecules that are in continuous, random motion, the combined volume of the molecules of the gas is negligible (i.e. gas particles have mass but no volume), attractive and repulsive forces between gas particles are negligible, kinetic energy is conserved, and the average kinetic energy does not change with time as long as temperature remains constant. All of the properties of ideal gases and their relationships are illustrated with the equation PV=nRT, where P is pressure, V is volume, n is the number of molecules, R is the gas constant, and T is the temperature. This is actually a combination of relationships, which are detailed in Boyle's law (PV=k), Charles' law (V/T=k), Gay-Lussac's law (P/T=k), and Avogadro's law (V/n=k). Also important when dealing with gases are the concepts of effusion and diffusion. Effusion is the escape of gas molecules through some material, while diffusion is the spread of gas molecules throughout a space or materials. However, both rates are dependent upon mass in the same way. We also discussed partial pressures and how they are related to total pressures and mole fractions (which are the relative percent compositions by mole of a single component of the mixture, represented as decimals.) Then we talked about real gases and how they deviate from ideal gases, which allowed us to segue back into our previous discussions of IMF's and polarity. Both are extremely valuable in understanding how real gases deviate from ideal gases. Real gases deviate the most from ideal behavior under high pressure and low temperatures because that is when particles are the closest and moving the slowest, thus allowing the IMF's to have the strongest effect.
We spent a lot of this week whiteboarding and doing concept tests, although we also spent some time messing around with liquid nitrogen, in order to better understand the concept of gases. I understand this section much better than I did Entropy and Thermochemistry. The most trouble I have int his section is remembering back to the stoichiometry. I also have some trouble with remembering the smaller relationships between specific things. I have been trying hard to participate in class, but without complete comfort in my knowledge, I find it hard to voice those ideas in class. I tend to understand the correct answer once it is explained, or even once it is identified, but until then I have trouble choosing the correct response or being able to explain my response. I don't have any concrete questions, but I certainly need more practice. After this section, I have been wondering a lot about the process of respiration and how exactly breathing works on a chemical level. It is fascinating.
