CHEM 10123/10125, Quiz 3
February 22, 2012
Name_____________________
(please print)
Significant figures and correct units count, show charges as appropriate, and please box your
answers!
1. (8 points) Fill in the table.
acidic,
basic,
or
neutral
soln?
strong or
weak?
Use
Ka, Kb,
or Kw?
Appropriate equilibrium equation?
[USE CHEMICAL EQUATION HERE, not
the equilibrium expression]
Formula of
conjugate
acid or
base?
NaNO3
HC2H3O2
2. (5 points) For the reaction (at 2300 K),
N2(g) + O2(g) ⇌ 2 NO(g)
Answer the following questions.
a.
Kc = 1.7 x 10–3
Is this a homogeneous or heterogeneous reaction?_______________________
b. Does the equilibrium lie to the left or the right?_____________________
c. If the volume of the container is increased, will the equilibrium shift to the left,
shift to the right, or remain unchanged?_________________________
d. If the volume of the container is increased, will the equilibrium constant get
bigger, get smaller, or remain unchanged?_________________________
e. If O2(g) is added to the reaction system, will the concentration of N2(g) get larger,
smaller, or remain unchanged? ___________________________
3. (6 points) SHOW ALL WORK. In the following equation,
CHO2–(aq) + H2O(l) ⇌ HCHO2(aq) + OH–(aq)
a) Label all conjugate acid/base pairs, and
b) determine the pH of an 0.25 M solution of CHO2– (Ka of HCHO2 is 1.8 x 10–4).
4. (5 points) SHOW ALL WORK. If an aqueous solution of unknown acid HA contains
0.318 mol acid per liter solution and has pH = 1.56, calculate Ka.
5. SHOW ALL WORK. It was found that 81.72 mL of an HNO3 solution are needed to
react completely with 570 mL of a LiOH solution that has a pH of 12.61.
a) (3 points) What is the molarity of the LiOH solution? _______________
b) (3 points) What is the molarity of the HNO3 solution? _______________
CHEM 10123/10125, Quiz 3
February 22, 2012
Name_____________________
(please print)
Significant figures and correct units count, show charges as appropriate, and please box your
answers!
1. (8 points) Fill in the table.
acidic,
basic,
or
neutral
soln?
strong or
weak?
Use
Ka, Kb,
or Kw?
Appropriate equilibrium equation?
[USE CHEMICAL EQUATION HERE, not
the equilibrium expression]
Formula of
conjugate
acid or
base?
KF
NaNO2
2. (5 points) For the reaction,
2 H2(g) + O2(g) ⇌ 2 H2O(g) Kc = 3.2 x 1081
Answer the following questions.
a. Is this a homogeneous or heterogenous reaction? __________________________
b. Does the equilibrium lie to the left or the right?______________________
c. If H2(g) is added to the reaction system, will the concentration of H2O(g) get larger,
smaller, or remain the same?______________________________
d. If the volume of the container is increased, will the equilibrium shift to the left,
shift to the right, or remain unchanged?_________________________
e. If the volume of the container is increased, will the equilibrium constant get
bigger, get smaller, or remain unchanged?_________________________
3. (6 points) SHOW ALL WORK. In the following equation,
C7H5O2–(aq) + H2O(l) ⇌ OH–(aq) + HC7H5O2(aq)
a) Label all conjugate acid/base pairs, and
b) determine the pH of an 0.25 M solution of C7H4O2– (Ka of HC7H5O2 is 6.5 x 10–5).
4. (5 points) SHOW ALL WORK. If an aqueous solution of unknown acid HA contains
0.0150 mol acid per liter solution and has pH = 2.29, calculate Ka.
5. SHOW ALL WORK. It was found that 97.22 mL of an HNO3 solution are needed to
react completely with 530 mL of a LiOH solution that has a pH of 11.96.
a) (3 points) What is the molarity of the LiOH solution? ______________
b) (3 points) What is the molarity of the HNO3 solution? ___________________