Gen. Chem.- Chapter 14
Choose the correct answer for each question.
 

1Which of the following solutions could be a buffer?
1L of 1M HBr + 1L of 1M KOH
1L of 1M HNO2 + 1L of 1M KNO2
1L of 1M HNO2 + 0.5L of 1M NaOH
both b. and c.

2What is the pH of a buffer solution containing 0.25 mol of HF and 0.30 mol of NaF?
Ka HF = 7.1 x 10-4?
3.23
3.07
3.15
7.00

3A buffer contains 0.25 mol of HF and 0.30 mol of NaF. 0.10 mol of HCl is added. What is the new pH? (Ka HF = 7.1 x 10-4)
1.58
2.91
3.23
5.94

4To prepare a buffer with a pH of 4.62, the best choice of a weak acid and its salt in equimolar amounts would be...
HF (Ka = 6.9 x 10-4)
HN3 (Ka = 2.40 x 10-5)
HClO (Ka = 2.80 x 10-8)
NH4+ (Ka = 4.70 x 10-11)

5The equil. pt. for a strong acid - strong base titration will be at a pH...
less than 7
greater than 7
exactly 7
cannot be determined from the information given.

6Which of the following statements is NOT true of a wk. base - strong acid titration curve?
A "flat spot" occurs in the titration curve at the half-equivalence point.
The equilalence point will be at pH<7.
The choice of indicator is not that important. Most indicators will do.
The pH changes less sharply near the equil. pt. than for a str. acid - str. base titration curve.

7Calculate the pH of 100 mL of 0.100 M HCl after 55.0 mL of 0.200 M NaOH is added.
5.20
7.00
9.56
11.8

8Calc. the pH of 50 mL of 0.100 M CH3COOH after 50 mL of 0.08 M KOH has been added.
4.44
5.35
8.90
10.0

9An acid base indicator will change color when...
the solution goes from acidic to basic.
the ratio [HIn] / [In-] goes from being less than 1 to greater than 1.
the ratio [HIn] / [In-] goes from being greater than 1 to less than 1.
Both b. and c.

10Which of the following indicators would be the best choice for a CH3COOH - KOH titration?
Thymolphthalein - Ka = 1 x 10-10
Phenol Red - Ka = 1 x 10-7
Bromocresol Green - Ka = 1 x 10-5
Thymol Blue - Ka = 1 x 10-2