General Chemistry Principles, Patterns, and Applications, 2011

Write the equilibrium expression for each reaction.
a. Calculate the partial pressure of both gaseous components at equilibrium in each reaction
if a 1.00 L reaction vessel initially contains 0.316 mol of H 2 or CO plus 0.500 mol CoO.
b. Using the information provided, calculate K p for the following reaction:
c.
H2 g
( ) + CO2( g) CO( g) + H2O( g)
Describe the shape of the graphs of [reactants] versus [products] as the amount of CoO
changes.
5. Hydrogen iodide (HI) is synthesized via H2 g
( ) + I2( g)
2HI g
for which K p = 54.5 at 425°C. Given a 2.0 L vessel containing 1.12 × 10 −2 mol of H 2 and 1.8 × 10 −3 mol of I 2 at
equilibrium, what is the concentration of HI? Excess hydrogen is added to the vessel so that the vessel now
contains 3.64 × 10 −1 mol of H 2 . Calculate Q and then predict the direction in which the reaction will proceed. What
( ),
are the new equilibrium concentrations?
A N S W E R S
1. Not at equilibrium; in both cases, the sum of the equilibrium partial pressures is less than the total pressure,
2.
3.
so the reaction will proceed to the right to decrease the pressure.
a. a. K = [H2O][H2]; K = [CO2][CO]
b.
b. PH 2O = 21.0 atm;
PH 2 = 0.27 atm;
PCO2 = 21.3 atm;
P CO
= 0.07 atm
c. K p = 0.14
d. The amount of CoO has no effect on the shape of a graph of products versus reactants as
long as some solid CoO is present.
15.5 Factors That Affect Equilibrium
L E A R N I N G O B JE C T I V E
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