Transcript Quiz 1. What is the equilibrium pH of a 0.175 M solution of the diprotic 1,5-pentanedioic acid? pKa1 = 4.345 and pKa2

Quiz
1. What is the equilibrium pH of a 0.175 M solution of the diprotic
1,5-pentanedioic acid? pKa1 = 4.345 and pKa2 = 5.422. Show your
work.
a. 11.4
c. 3.6
b. 2.6
d. 2.81 x 10-3
2. From problem 1 above, what is the equilibrium concentration of
the base form of 1,5-pentanedioic acid?
a. 2.8 x 10-3 M
c. 4.7 x 10-11 M
b. 0.175 M
d. 3.8 x 10-6
Quiz
3. Consider a buffer solution made from the weak base A2- with
pKa1 = 4.5 and pKa2 = 9.0. In a buffer solution with pH = 8.7, which
Henderson-Hasselbalch equation should be used for calculations?
[HA- ]
a. pH  9.0  log
[ H 2 A]
[ A 2- ]
c. pH  9.0  log
[HA- ]
b.
[ A 2- ]
pH  4.5  log
[HA- ]
d.
[HA- ]
pH  4.5  log
[ H 2 A]
4. Consider a buffer where the [HA] + [A-] = 0.250 M and [A-] / [HA] =
2.00. What is [HA]? Show your work.
a. 0.125 M
c. 0.167 M
b. 8.33 x 10-2 M
d. none of these