Question

1.) An aqueous solution contains 0.23 M hydrofluoric acid.

One Liter of this solution could be converted into a buffer by the addition of:

(Assume that the volume remains constant as each substance is added.)

0.12 mol HClO₄

0.23 mol KNO₃

0.24 mol HClO₄

0.24 mol KF

0.117 mol NaOH

2.)

An aqueous solution contains 0.34 M ammonia.

One liter of this solution could be converted into a buffer by the addition of:

(Assume that the volume remains constant as each substance is added.)

0.17 mol KOH

0.17 mol HCl

0.34 mol NaCl

0.35 mol NH₄Cl

0.35 mol HCl

3.)

Design a buffer that has a pH of 4.67 using one of the weak acid/conjugate base systems shown below.

Weak Acid	Conjugate Base	Ka	pKa
HC2O4-	C2O42-	6.4×10-5	4.19
H2PO4-	HPO42-	6.2×10-8	7.21
HCO3-	CO32-	4.8×10-11	10.32

How many grams of the sodium salt of the weak acid must be combined with how many grams of the sodium salt of its conjugate base, to produce 1.00 L of a buffer that is 1.00 M in the weak base?

grams sodium salt of weak acid =  g

grams sodium salt of conjugate base =  g

4.)Design a buffer that has a pH of 4.29 using one of the weak base/conjugate acid systems shown below.

Weak Base	Kb	Conjugate Acid	Ka	pKa
CH3NH2	4.2×10-4	CH3NH3+	2.4×10-11	10.62
C6H15O3N	5.9×10-7	C6H15O3NH+	1.7×10-8	7.77
C5H5N	1.5×10-9	C5H5NH+	6.7×10-6	5.17

How many grams of the bromide salt of the conjugate acid must be combined with how many grams of the weak base, to produce 1.00 L of a buffer that is 1.00 M in the weak base?

grams bromide salt of conjugate acid =

grams weak base =

Answer 1