Feb 28th Session

SI Chem 178
Leader: Emily
Feb 28, 2013
Review: (End of Ch 16 stuff)
In binary acids, (HX, such as HCl, HBr, HF, HI) which factor plays a role in determining
acid strength?
In oxyacids, what are two things that INCREASE acid strength? (HClO4 is an example.)
Amines are Lewis acids or bases? Why? Draw one here 
Al 3+ would make a solution acidic, neutral, or basic?
Weak acids and bases have WEAK or NEGLIGIBLE conjugates?
Strong acids/bases have WEAK or NEGLIGIBLE conjugates?
New Stuff: (Ch 17 sections 1-3) Sugg probs: 1-7, 16, 17, 21, 25, 29, 31, 33, 35, 37, 41, 43
In buffer solutions of equal molar amounts of weak acid and conjugate salt, what can we
assume about our pH and pKa?
Which of the following won’t function as a buffered solution? Why not?
HCl, NaCl
C2H5COOH, C2H5COOHCO3-, CO3 2HNO3, NO3Benzoic acid, Sodium benzoate
What is the Henderson-Hasselbalch equation? Do we use concentrations or moles in it?
What is the pH of a buffer made of 0.12M benzoic acid and 0.2M sodium benzoate?
(Ka=6.3*10^-5) Do you need to make an ICE table? Do you need a “Before/After” table?
Increasing OH- in an acidic buffered solution increases: HX or X- ? What else is made?
Increasing H+ in an acidic buffered solution increases HX or X- ? If a strong acid is the
source of this H+, does its conjugate base affect the pH?
17.16a What is the pH of a solution of 0.25M sodium formate (HCOONa) and 0.1M
formic acid? (HCOOH) (Ka= 1.8*10^-4)
17.17 a. What is the %ionization of 0.0075M butanoic acid with a Ka of 1.5*10^-5?
b. What is the % ionization of the same solution with .085 sodium butanoate added? (Can
we still avoid ICE tables for this?
17.25 Please make a pH=3 buffer solution from 1.25L of 1M HF and as much NaF as
a. What is the initial pH of the HF solution?
b. How much NaF should be added?
17.34 In titrating a weak monoprotic acid versus a strong monoprotic acid…..
a. Is the amount of base required to get to the equivalence point the same?
b. Which has a higher initial pH?
c. How will the pH of their equivalence points differ?
d. How will their pH differ after excess base has been added?
e. Which will require an indicator with a higher pH range?
17.43 b/d We have a 20 mL sample of HBr, and we are titrating it with 0.2M NaOH what
is the pH after adding
b. 19.9 mL of base
d. 20.1 mL of base