chemistry

12U Equilibrium Unit Test

Multiple Choice K/U
Identify the letter of the choice that best completes the statement or answers the question.

____ 1. When solid lead(II) phosphate is in equilibrium with its ions, the ratio of lead(II) ions to phosphate ions is which of the following?
a.
1:1
d.
2:3
b.
1:2
e.
3:2
c.
2:1

____ 2. In a saturated solution of silver phosphate, the concentration of silver ion is 4.5  10-4 mol/L. The Ksp of silver phosphate would be which of the following?
a.
6.8  10-8
d.
1.0  10-11
b.
1.4  10-14
e.
none of the above
c.
1.5  10-15

____ 3. For the equilibrium system below, which of the following would result in an increase in the quantity of PCl5(g)?
PCl3(g) + Cl2(g) PCl5(g) + 45 kJ
a.
increasing temperature
d.
removing some Cl2(g)
b.
increasing the size of the container
e.
injecting some He gas
c.
decreasing temperature

____ 4. 10.0 mol of ammonia gas is injected into a 4.0 L container. At equilibrium 1.2 mol of hydrogen gas is found in the container. The number of moles of ammonia gas left in the container must be which of the following?
N2(g) + 3H2(g) 2NH3(g) + 94 kJ
a.
6.8
d.
8.8
b.
6.4
e.
9.2
c.
8.6

____ 5. A closed flask contains this equilibrium
2 NO2(g) (brown gas) N2O4(g) (colourless gas)
When the equilibrium is heated at a constant pressure it gets browner. This must mean which of the following?
a.
Ke is very large
d.
both a and b
b.
it is endothermic
e.
both a and c
c.
it is exothermic

____ 6. Which equilibrium shows a decrease in [products] when the volume increases? I. 2H2(g) + O2(g) 2H2O(g) II. Cl2(g) + PCl3(g) PCl5 (g) III. H2(g) + I2(g) 2HI(g) IV. 2NH3(g) N2 + 3H2(g)
a.
I
d.
III and IV
b.
I and II
e.
II
c.
IV

____ 7. Consider this equilibrium
4HCl(g) + O2(g) 2H2O(g) + 2Cl2(g)
The equilibrium law expression for the balanced chemical equation would be
a.
[HCl][O2] / [H2O][Cl2]
d.
[HCl]4[O2]