Tuesday, February 13, 2007
Tuesday, Day 2
Honors: we did several permutations of molarity problems starting with some combination of grams, moles, liters, molarity, and a specific solute. We began to discuss solution dilution and the formula involved.
Regents: we began stoichiometry using balanced chemical equations. We solved "mole to mole" problems and then did some mole to gram and mole to liter problems for practice.
AP: we learned to THINK about equilibrium calculations by analyzing the RELATIVE quantity of weak acid that is ionized vs. un-ionized, which tells us when we can neglect the amount of acid that is lost via ionization RELATIVE to the initial amount of acid.
All of that boils down to the 5% rule, which let's us know whether we can "neglect x" RELATIVE to the initial acid concentration.
We will do the same thing for weak bases (mostly organic AMINES).
We also showed that, as a weak acid is more and more dilute, its percent ionization increases YET, ironically, the pH of its solution gets closer to 7 (because, with enough water, all solutions eventually dilute to a pH of 7, at 298K).
I can't post the AP exam question until late tonight so it will not be due tomorrow. You can download it then.
Regents: we began stoichiometry using balanced chemical equations. We solved "mole to mole" problems and then did some mole to gram and mole to liter problems for practice.
AP: we learned to THINK about equilibrium calculations by analyzing the RELATIVE quantity of weak acid that is ionized vs. un-ionized, which tells us when we can neglect the amount of acid that is lost via ionization RELATIVE to the initial amount of acid.
All of that boils down to the 5% rule, which let's us know whether we can "neglect x" RELATIVE to the initial acid concentration.
We will do the same thing for weak bases (mostly organic AMINES).
We also showed that, as a weak acid is more and more dilute, its percent ionization increases YET, ironically, the pH of its solution gets closer to 7 (because, with enough water, all solutions eventually dilute to a pH of 7, at 298K).
I can't post the AP exam question until late tonight so it will not be due tomorrow. You can download it then.
# posted by C @ 7:15 PM 
