Review for Equilibrium Exam
Demonstration Review:
1) In an aqueous solution of potassium chromate, the following equilibrium system is established:
2CrO42–(aq) + 2H+(aq) Cr2O72–(aq) + H2O(l)
Yellow
Orange
a) When a little dilute sulfuric acid is added to the system above (adding H+ ions), the color of the
solution should change from _______________ to _______________ .
This indicates that the concentration of Cr2O72–(aq) ions has ___________________ while the
concentration of CrO42–(aq) ions has ___________________.
b) When a little dilute sodium hydroxide solution is added to the resulting solution, the color of the
solution should change from _________________ to __________________ .
This indicates that the concentration of CrO42–(aq) ions has ___________________while the
concentration of Cr2O72–(aq) ions has _____________________.
2) Given the reaction at equilibrium: N2(g) + O2(g)  2NO(g) as the concentration of N2(g) increases,
the concentration of O2(g) will
1. decrease
2. increase
3. remains the same
3) Given the equilibrium system at 25°C: NH4Cl(s)  NH4+(aq) + Cl-(aq) (H = +3.5 kcal/mol)
What change will shift the equilibrium to the right?
1.
2.
3.
4.
decreasing the temperature to 15°C?
increasing the temperature to 35°C?
dissolving NaCl crystals in the equilibrium mixture?
dissolving NH4NONH3 crystals in the equilibrium mixture?
4) In which reaction will the point of equilibrium shift to the left when the pressure on the system is
increased?
1.
2.
3.
4.
C(s) + O2(g)  CO2(g)
CaCO3(s)  CaO(s) + CO2(g)
2Mg(s) + O2(g)  2MgO(s)
2H2(g) + O2(g)  2H2O(g)
5) Which substance is produced by the Haber process?
1.
2.
3.
4.
aluminum
ammonia
nitric acid
sulfuric acid
6) Given the reaction at equilibrium: 2 SO2(g) + O2(g)  2 SO3(g) + heat
Which change will shift the equilibrium to the right?
1.
2.
3.
4.
adding a catalyst
adding more O2(g)
decreasing the pressure
increasing the temperature
7) A 0.1-molar solution of acetic acid (CH3COOH) has a pH of about
a. 1
b. 3
c. 7
d. 10
e. 14
8)
The above materials were sealed in a flask and allowed to come to equilibrium at a certain
temperature. A small quantity of O2(g) was added to the flask, and the mixture allowed to return
to equilibrium at the same temperature. Which of the following has increased over its original
equilibrium value?
a. the quantity of NO2(g) present
b. the quantity of NO(g) present
c. the equilibrium constant, K
d. the rate of the reaction
e. the partial pressure of NO(g)
9)
In order to increase the value of the equilibrium constant, K, which of the following changes must
be made to the above equilibrium?
b. increase the temperature
c. increase the volume
d. decrease the temperature
e. add CO(g)
f. add a catalyst