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Schedule to Exam 2

Date Day Topics
2/6 Wed Brief Exam 1 review/overview. Explained exam dos and don'ts. Officially started in on Chapter 6 - Equilibrium. Discussed the 2 views of equilibrium - (1) thermodynamics, and (2) kinetics.
2/8 Fri True K's (thermodynamic K's) do not have units. K's should actually be expressed using activities. Importance of knowing the differences in K, Kp, and Kc. Also discussed the way that K appears and it's value will totally depend on the way in which you balance the equation.
2/11 Mon How to set-up and solve virtually all equilibrium problems. Showed how to set up and solve and "ICE" table. Also introduced LeChatlier's Principle, comparing Q to K.
2/13 Wed More on equilibrium and LeChatlier's Principle. Showed how Q "chases" K as reactions come to equilibrium. Only temperature can change K for a given reaction. Concentration and pressure changes will change Q (not K). Showed temperature dependence of the equilibrium constant - the van't Hoff Equation - which looks a LOT like the Clausius-Clapeyron Equation.
2/15 Fri Pointed out some things to watch for on hw03. Showed how to work number 31 on hw03. Started on acid/base theory. Gave 3 definitions of acids and bases: 1) Arrhenius, 2) Lowry-Bronsted, and 3) Lewis. We will be concerned mainly with the Lowry-Bronsted definition.
2/18 Mon Know your 7 Strong Acids and 8 Strong Bases. Most weak acids and bases are weak electrolytes - only slightly ionized in aqueous solutions. Water is a very weak electrolyte. Showed the dissociation reaction for water and Kw. Restated importance of knowing what conjugate acids and conjugate bases are. Defined an amphiteric species.
2/20 Wed Discussed the definition of pH, pOH, pK, and pX. Discussed the pH scale and what the range of acidity was.
2/22 Fri Gave an example of an acid/base neutralization where one of the two is in limiting amounts. Added HCl to NaOH and the NaOH was in excess. Got the pH of the resulting solution. Showed how ALL acid/base equilibria will look. In particular I went through the ICE table for a weak acid, HA. I pointed out the help sheet for a weak acid (HA) in solution. I also named problems as "Type 1" problems when one and only one species is put in solution. This is the type of problems that are in Chapter 7. Type 2 problems (2 species) will be in Chapter 8. of problems.
2/25 Mon Talked about relative strengths of acids and there conjugate bases. Showed how to get a Kb from Ka for its conjugate (Kw = Ka Kb). Discussed the Leveling Effect in water. Talked about how you make a salt of a weak acid and a salt of a weak base. Then pointed out the other 3 help sheets for Type 1 problems.
2/27 Wed Discussed the basics of a neutral salt, acidic salt, and a basic salt. Also showed how to tell whether a mixed salt (acid and base) will be more basic or more acidic. Then showed how the mass action expression for a weak acid can be shown as 2 ratios: Ka/[H+] = [A-]/[HA]. Then I defined what "fraction of species" is. I then showed a plot of fraction of species vs pH. One can see how the 2 conjugates (HA and A-) trade off on their rolls as the dominate species. The switch over point is when pH = pKa. That is the point where the fractions are both 1/2. This provides a segue to polyprotic acids.
2/29 Fri Covered som more on polyprotic acids. Covered more on fraction of species and interpretation of a fraction of species plot. Defined the material balance and the charge balance. The charge balance is essential when making calculations in very dilute solutions where the concentration terms are very close to 10-7 M.
3/3 Mon Finish Chapter 7
Homework 5 is due tonight by 11:59 PM.
3/5 Wed Quick Exam 2 overview. Start Chapter 8.
3/6 Thu EXAM 2, 7-9 PM Chapters 6 and 7
3/7 Fri Chapter 8
3/10 Mon Spring Break!
3/12 Wed Spring Break!
3/14 Fri Spring Break!