Ch 14 Key

NVCC AL Campus CHM 112 Worksheet
Chapter 14: Chemical Equilibrium
Q1.
Name:________________________
Write the equilibrium expression for following reactions. Hint: what happens to liquids and solids in these expressions?
1) SO2 (g) + NO2 (g)
SO3(g) + NO (g)
𝐾𝑐 =
2) 5 Fe2+ (aq) + MnO4- (aq) + 8 H+ (aq)
5 Fe3+ (aq) + Mn2+ (aq) + 4 H2O (l)
𝐾𝑐 =
3) CO32- (aq) + 2 H+ (aq)
[𝐹𝑒 3+ ]5 [𝑀𝑛2+ ]
[𝐹𝑒 2+ ]5 [𝑀𝑛𝑂4 − ][𝐻 + ]8
H2O (l) + CO2 (g)
𝐾𝑐 =
4) N2O3 (g)
For the reaction:
2 SO2 (g) + O2 (g)
Kp = 1.23
At 298 K, Kc = 1.3 × 10-2 for the reaction:
2 NO (aq) + Br2 (g)
2 NOBr (g)
What is the value of Kc for the following reaction?
NOBr (g)
[𝐶𝑂3 2− ][𝐻 + ]2
NO (aq) + ½ Br2 (g)
Kc = 8.8
[𝑁𝑂][𝑁𝑂2 ]
[𝑁2 𝑂3 ]
2 SO3 (g) , Kc = 30.0 at 25 C
What is Kp for the reaction at the same temperature?
Q3.
[𝐶𝑂2 ]
NO (g) + NO2 (g)
𝐾𝑐 =
Q2.
[𝑆𝑂3 ][𝑁𝑂]
[𝑆𝑂2 ][𝑁𝑂2 ]
NVCC AL Campus CHM 112 Worksheet
Q4.
Consider the equilibrium reaction H2 (g) + I2 (g)
2 HI (g); Kc= 50.5
A vessel contains 0.010 M HI, 0.0050 M H2 and 0.015 M I2.
Is this mixture at equilibrium?
Nope!
If not, then which direction will the reaction proceed to attain equilibrium?
To the right (more products)
Q5.
For the reaction: CO (g) + H2O (g)
CO2 (g) + H2 (g) , Kp = 4.0
An equilibrium mixture was found to contain 0.60 atm CO, 0.20 atm of steam, and 0.50 atm CO2. What is the
equilibrium partial pressure of H2 in this mixture?
PH2 = 0.96 atm
NVCC AL Campus CHM 112 Worksheet
Q6.
Given the following information,
CoO(s) + H2 (g)
Co (s) + H2O (g)
Kc = 67
CoO(s) + CO (g)
Co (s) + CO2 (g)
Kc =490
Calculate Kc for the following reaction:
2H2 (g) + 2CO2 (g)
2CO (g) + 2H2O (g)
Kc = 0.019
Q7.
Consider the reaction: NH4HS (s)
NH3 (g) + H2S (g), Kc = 1.2 x 104.
What are the equilibrium concentrations of NH3 and H2S if a solid sample of NH4HS is placed in a reaction vessel
and decomposes until equilibrium gets established?
[NH3] = 0.011 M
[H2S] = 0.011 M
NVCC AL Campus CHM 112 Worksheet
Q8. Consider the equilibrium reaction
N2O4 (g)
ΔH° = 58.0 kJ
2 NO2 (g)
In which direction will the equilibrium shift when the following changes are made? Explain your reasoning.
(A) N2O4 (g) is added?
Right
(B) NO2 (g) is removed?
Right
(C) The volume of the reaction vessel is increased?
Right
(D) The temperature is decreased?
Left
(E) The total pressure is increased by adding some N2 (g)
No change
Q9.
Consider the following equilibrium
6CO2 (g) + 6 H2O(l)
C6H12O6 (s) + 6 O2(g)
ΔH = 2816 kJ
How will each of the following changes affect the equilibrium yield of C6H12O6. Explain your reasoning.
1) Increasing Pressure of CO2
More C6H12O6
2) Increasing temperature
More C6H12O6
3) Removing CO2
Less C6H12O6
4) Decreasing the volume of the reaction vessel
No effect
5) Removing part of C6H12O6 (s)
No effect
6) Adding a catalyst
No effect
NVCC AL Campus CHM 112 Worksheet
Q10.
A 7.24 g sample of IBr is placed in a 0.225 L vessel and heated to 500. K. The following reaction takes place.
2 IBr (g)
I2 (g) + Br2(g)
At equilibrium, the partial pressure of Br2 is 3.01 atm. Calculate Kp for this reaction.
Kp = 68
Calculate Kc for the same reaction.
Kc = 68
Q11.
Consider the reaction
2 SO3 (g)
2 SO2 (g) + O2 (g)
In an experiment, SO3 (g) at 1.0 atm was placed in an empty reaction vessel. After equilibrium was established, the
vessel contained 0.60 atm of SO2 (g). Calculate Kp for the reaction.
Kp = 0.68
NVCC AL Campus CHM 112 Worksheet
Q12.
Consider the reaction. 2NO2 (g)
2NO (g) + O2 (g)
A 0.240 mol sample of NO2 was placed in an empty 2.00-L flask at 700 K. At equilibrium, the flask contained 0.179
mol of NO2. Calculate Kc for the reaction.
Kc = 0.00177 or 1.77 × 10-3
Q13.
Consider the following reaction
PCl5 (g)  PCl3 (g) + Cl2 (g)
ΔH° = +87.9 kJ
In which direction will the equilibrium be shifted by the following changes?
a) Adding PCl3
Left
b) Removing Cl2
Right
c) Removing PCl5
Left
d) Adding a catalyst
No change
e) Increasing the temperature of the reaction mixture
Right
f) Adding He gas to the reaction mixture at constant volume
g) Decreasing the volume of the reaction vessel
Left
No change
NVCC AL Campus CHM 112 Worksheet
Q14.
At 600 K, Kp = 4.10 × 10-3 for the following reaction
COCl2 (g)
CO (g) + Cl2 (g)
Calculate the equilibrium pressures of all the components in the system if the starting pressure of COCl2 was 0.124 atm.
PCOCl2 = 0.103 atm
PCO = 0.0206 atm
PCl2 = 0.0206 atm
Q15.
For the reaction 2 NO2 (g)
2 NO (g) + O2 (g),
Kp = 6.5×10-6 at 450 C.
If a reaction vessel at this temperature initially contains 0.500 atm of NO2, what are the pressures of all species at
equilibrium?
PNO2 = 0.49 atm
PNO = 0.015 atm
PO2 = 0.0074 atm