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Equilibrium constant
Related Topics
Wize University Chemistry Textbook > Equilibrium
The Equilibrium Constant (K)
4 Activities
The equilibrium constant for the process: AgCl (s)
⇌
Ag
+
(aq) + Cl
-
(aq) is 1.0x10
-10
. What would be the equilibrium concentration of Ag
+
in solution when 10 g of the AgCl salt is added to pure water?
1.0x10
-10
1.0x10
-9
1.0x10
5
1.0x10
-4
1.0x10
-5
I don't know
Check Submission
More The Equilibrium Constant (K) Questions:
Equilibrium
Consider the following equilibria:
2
H
C
l
(
g
)
⇌
H
2
(
g
)
+
C
l
2
(
g
)
K
c
,
1
2HCl_{(g)} \rightleftharpoons H_{2(g)} +Cl_2{(g)} \hspace{20pt} K_c,1
2
H
C
l
(
g
)
⇌
H
2
(
g
)
+
C
l
2
(
g
)
K
c
,
1
2
H
2
S
2
(
g
)
⇌
2
H
2
(
g
)
+
S
2
(
g
)
K
c
,
2
2H_2S_2{(g)} \rightleftharpoons 2H_{2(g)} +S_2{(g)} \hspace{20pt} K_c,2
2
H
2
S
2
(
g
)
⇌
2
H
2
(
g
)
+
S
2
(
g
)
K
c
,
2
Equilibrium: Reaction Quotient
Silver chloride will react with acetic acid to form the complex ion silver acetate. A reaction mixture is prepared by adding 0.25 g of AgCl to a 1.25 L solution that already contains 4.6×10
‐6
M Ag(CH
3
COO)(aq), 2.3×10
‐3
M Cl
-
, 1.1×10
‐8
M H
+
, and 0.010M CH
3
COOH. Based on this information, which of the statements below is true?
A
g
C
l
(
s
)
+
C
H
3
C
O
O
H
(
a
q
)
⇌
A
g
(
C
H
3
C
O
O
)
(
a
q
)
+
C
l
−
(
a
q
)
+
H
+
(
a
q
)
K
=
5.87
×
10
−
16
AgCl(s)+CH_3 COOH(aq)⇌Ag(CH_3 COO)(aq)+Cl^- (aq)+H^+ (aq)\qquad K = 5.87×10^{-16}
A
g
C
l
(
s
)
+
C
H
3
C
O
O
H
(
a
q
)
⇌
A
g
(
C
H
3
C
O
O
)
(
a
q
)
+
C
l
−
(
a
q
)
+
H
+
(
a
q
)
K
=
5.87
×
1
0
−
16
After allowing this solution to rest for some time:
Equilibrium: Reaction Quotient
Silver chloride will react with acetic acid to form the complex ion silver acetate. A reaction mixture is prepared by adding 0.25 g of AgCl to a 1.25 L solution that already contains 4.6×10
‐6
M Ag(CH
3
COO)(aq), 2.3×10
‐3
M Cl
-
, 1.1×10
‐8
M H
+
, and 0.010M CH
3
COOH. Based on this information, which of the statements below is true?
A
g
C
l
(
s
)
+
C
H
3
C
O
O
H
(
a
q
)
⇌
A
g
(
C
H
3
C
O
O
)
(
a
q
)
+
C
l
−
(
a
q
)
+
H
+
(
a
q
)
K
=
5.87
×
10
−
16
AgCl(s)+CH_3 COOH(aq)⇌Ag(CH_3 COO)(aq)+Cl^- (aq)+H^+ (aq)\qquad K = 5.87×10^{-16}
A
g
C
l
(
s
)
+
C
H
3
C
O
O
H
(
a
q
)
⇌
A
g
(
C
H
3
C
O
O
)
(
a
q
)
+
C
l
−
(
a
q
)
+
H
+
(
a
q
)
K
=
5.87
×
1
0
−
16
After allowing this solution to rest for some time:
Equilibrium
Consider the following equilibria:
2
H
C
l
(
g
)
⇌
H
2
(
g
)
+
C
l
2
(
g
)
K
c
,
1
2HCl_{(g)} \rightleftharpoons H_{2(g)} +Cl_2{(g)} \hspace{20pt} K_c,1
2
H
C
l
(
g
)
⇌
H
2
(
g
)
+
C
l
2
(
g
)
K
c
,
1
2
H
2
S
2
(
g
)
⇌
2
H
2
(
g
)
+
S
2
(
g
)
K
c
,
2
2H_2S_2{(g)} \rightleftharpoons 2H_{2(g)} +S_2{(g)} \hspace{20pt} K_c,2
2
H
2
S
2
(
g
)
⇌
2
H
2
(
g
)
+
S
2
(
g
)
K
c
,
2
Equilibrium
Consider the following equilibria:
2
H
C
l
(
g
)
⇌
H
2
(
g
)
+
C
l
2
(
g
)
K
c
,
1
2HCl_{(g)} \rightleftharpoons H_{2(g)} +Cl_2{(g)} \hspace{20pt} K_c,1
2
H
C
l
(
g
)
⇌
H
2
(
g
)
+
C
l
2
(
g
)
K
c
,
1
2
H
2
S
2
(
g
)
⇌
2
H
2
(
g
)
+
S
2
(
g
)
K
c
,
2
2H_2S_2{(g)} \rightleftharpoons 2H_{2(g)} +S_2{(g)} \hspace{20pt} K_c,2
2
H
2
S
2
(
g
)
⇌
2
H
2
(
g
)
+
S
2
(
g
)
K
c
,
2
Equilibrium
Consider the following equilibria:
2
H
C
l
(
g
)
⇌
H
2
(
g
)
+
C
l
2
(
g
)
K
c
,
1
2HCl_{(g)} \rightleftharpoons H_{2(g)} +Cl_2{(g)} \hspace{20pt} K_c,1
2
H
C
l
(
g
)
⇌
H
2
(
g
)
+
C
l
2
(
g
)
K
c
,
1
2
H
2
S
2
(
g
)
⇌
2
H
2
(
g
)
+
S
2
(
g
)
K
c
,
2
2H_2S_2{(g)} \rightleftharpoons 2H_{2(g)} +S_2{(g)} \hspace{20pt} K_c,2
2
H
2
S
2
(
g
)
⇌
2
H
2
(
g
)
+
S
2
(
g
)
K
c
,
2
Equilibrium
Consider the following equilibria:
2
H
C
l
(
g
)
⇌
H
2
(
g
)
+
C
l
2
(
g
)
K
c
,
1
2HCl_{(g)} \rightleftharpoons H_{2(g)} +Cl_2{(g)} \hspace{20pt} K_c,1
2
H
C
l
(
g
)
⇌
H
2
(
g
)
+
C
l
2
(
g
)
K
c
,
1
2
H
2
S
2
(
g
)
⇌
2
H
2
(
g
)
+
S
2
(
g
)
K
c
,
2
2H_2S_2{(g)} \rightleftharpoons 2H_{2(g)} +S_2{(g)} \hspace{20pt} K_c,2
2
H
2
S
2
(
g
)
⇌
2
H
2
(
g
)
+
S
2
(
g
)
K
c
,
2
Equilibrium
Consider the following equilibria:
2
H
C
l
(
g
)
⇌
H
2
(
g
)
+
C
l
2
(
g
)
K
c
,
1
2HCl_{(g)} \rightleftharpoons H_{2(g)} +Cl_2{(g)} \hspace{20pt} K_c,1
2
H
C
l
(
g
)
⇌
H
2
(
g
)
+
C
l
2
(
g
)
K
c
,
1
2
H
2
S
2
(
g
)
⇌
2
H
2
(
g
)
+
S
2
(
g
)
K
c
,
2
2H_2S_2{(g)} \rightleftharpoons 2H_{2(g)} +S_2{(g)} \hspace{20pt} K_c,2
2
H
2
S
2
(
g
)
⇌
2
H
2
(
g
)
+
S
2
(
g
)
K
c
,
2
Equilibrium
Consider the following equilibria:
2
H
C
l
(
g
)
⇌
H
2
(
g
)
+
C
l
2
(
g
)
K
c
,
1
2HCl_{(g)} \rightleftharpoons H_{2(g)} +Cl_2{(g)} \hspace{20pt} K_c,1
2
H
C
l
(
g
)
⇌
H
2
(
g
)
+
C
l
2
(
g
)
K
c
,
1
2
H
2
S
2
(
g
)
⇌
2
H
2
(
g
)
+
S
2
(
g
)
K
c
,
2
2H_2S_2{(g)} \rightleftharpoons 2H_{2(g)} +S_2{(g)} \hspace{20pt} K_c,2
2
H
2
S
2
(
g
)
⇌
2
H
2
(
g
)
+
S
2
(
g
)
K
c
,
2
Practice: Calculating Equilibrium Concentrations
Iodine chloride (ICl) can decompose, forming iodine and chlorine gases. If a reaction vessel is prepared by filling a 5.00 L container with 0.500 mol each of ICl, I
2
, and Cl
2
.
2
I
C
l
(
g
)
⇌
I
2
(
g
)
+
C
l
2
(
g
)
K
C
=
0.110
(
a
t
25
°
C
)
2ICl(g)⇌I_2 (g)+Cl_2 (g)\qquad K_C = 0.110\ (at \ 25°C)
2
I
C
l
(
g
)
⇌
I
2
(
g
)
+
C
l
2
(
g
)
K
C
=
0.110
(
a
t
25°
C
)
a) In which direction will the reaction proceed (towards products or reactants)? Show how you determined your answer.
Equilibrium constant
Which of the following is not included in an equilibrium equation?
Equilibrium constant
A 1.0 L flask was loaded and the system was allowed to reach equilibrium at 25 °C. The equilibrium mixture was found to contain: 1.5 mol Cr (S), 1.5 mol CCI
4
(g), 2.3 mol CrCl
3
, (g), and 2.5 mol C (S). Determine the K
c
value for this reaction at 25 °C.
4
C
r
(
s
)
+
3
C
C
l
4
(
g
)
⇌
4
C
r
C
l
3
(
g
)
+
3
C
(
s
)
Δ
H
=
26.9
k
J
4Cr(s)+3CCl_4 (g)\rightleftharpoons4CrCl_3 (g)+3C(s)\qquad ΔH = 26.9 kJ
4
C
r
(
s
)
+
3
C
C
l
4
(
g
)
⇌
4
C
r
C
l
3
(
g
)
+
3
C
(
s
)
Δ
H
=
26.9
k
J
Equilibrium constant: Reaction quotient
Consider the reaction:
A
+
2
B
⇌
C
+
D
A + 2B ⇌ C + D
A
+
2
B
⇌
C
+
D
At a particular temperature this reaction is reactant-favoured at equilibrium. If for the current concentrations the forward reaction is favoured, which of the following statements is true?
Equilibrium: ICE table
Given the following reaction, if we start with 16moles of CH
2
=CHCH
3
(g), 16 moles of NH
3
(g) and 320moles of O
2
(g) in a 1L container, what will the equilibrium concentration be for H
2
O(g)?
CH
2
=CHCH
3
(g) + NH
3
(g) + 32O
2
(g) ⇌ CH
2
=CHC≡N(g) + 3H
2
O(g)
K
=1.2×10
94
For this problem, since the K value is very large, the reaction will go to completion. We will have 1 ICE table for the reaction going to completion and a second ICE table for the reverse reaction where we will find the equilibrium concentrations!
ICE Tables
H
2
and I
2
are placed in a closed flask such that the concentrations of H
2
and I
2
are both 0.10 M respectively. The mixture is heated to 400
o
C and equilibrium is reached. Analysis of the equilibrium mixture finds H
I
to have a concentration of 0.050 M. Calculate the value of the equilibrium constant,
K
c
. H
2
(g) + I
2
(g) ⇌ 2 HI (g)
Solution:
Concept Clarifier
Consider the following reaction
2
S
O
2
+
O
2
⇌
2
S
O
3
\rm 2\ {SO_2} \quad+\quad {O_2}\quad \xrightleftharpoons{\hspace{1.5cm}}\quad 2\ {SO_3}
2
S
O
2
+
O
2
2
S
O
3
Δ
H
0
=
−
180
k
J
/
m
o
l
\Delta H^0=-180\ kJ/mol
Δ
H
0
=
−
180
k
J
/
m
o
l
Equilibrium constant: Kc
A one liter vessel was filled with 0.398 mol of NOCl(g). Then the temperature of the system was increased to 245 °C to undergo the following reaction:
2
N
O
C
l
(
g
)
⇌
2
N
O
(
g
)
+
C
l
2
(
g
)
2NOCl(g) \rightleftharpoons 2NO(g) +Cl_2(g)
2
N
O
C
l
(
g
)
⇌
2
N
O
(
g
)
+
C
l
2
(
g
)
When equilibrium was attained, the concentration of Cl
2
was 0.0225 mol/liter. Calculate the value of K
c
at 245 °C for the reaction.
Equilibrium constant: Kc
A 1.0 L flask was loaded and the system was allowed to reach equilibrium at 25 °C. The equilibrium mixture was found to contain: 1.5 mol Cr (S), 1.5 mol CCI
4
(g), 2.3 mol CrCl
3
, (g), and 2.5 mol C (S). Determine the K
c
value for this reaction at 25 °C.
Equilibrium: ICE Table
Cyclohexane (C
6
H
12
) undergoes an isomerization in the presence of the appropriate catalyst to form a compound called MCP.
C
6
H
12
(g)
⇌
MCP (g) K
c
= 0.143 at 25
o
C
The initial concentrations are [C
6
H
12
] = 0.200 M and [MCP] = 0.100 M. What are the equilibrium concentrations of these two compounds?
Equilibrium: Magnitude of equilibrium constant
The value of K
c
for a particular chemical equilibrium is 1.0x10
13
. Hence, we can conclude:
Equilibrium constant
Which of the following expression is the correct equilibrium-constant expression for the reaction below?
HF (aq) + H
2
O (l)
⇌
H
3
O
+
(aq) + F
-
(aq)
Equilibrium Constant: Kp
Consider the following reaction:
N
2
O
4
(g)
⇌
2 NO
2
(g)
A flask is charged with 6.000 atm of N
2
O
4
(g) and 4.000 atm of NO
2
(g) at 25
o
C. After equilibrium is reached the partial pressure of NO
2
is 1.536 atm. Calculate K
p
for the reaction.
Equilibrium: Concentration
An equilibrium mixture of CO, O
2
and CO
2
at a certain temperature contains [CO
2
] = 0.0010 M and [O
2
] = 0.0015 M. At this temperature the equilibrium constant K
c
= 1.4x102.
2 CO (g) + O
2
(g)
⇌
2 CO
2
(g) + heat
What is the equilibrium concentration of CO?
Equilibrium constant
Consider the following reaction of mercury and oxygen:
2 Hg (l) + O
2
(g)
⇌
2 HgO (s)
For this reaction, the equilibrium amounts of reactants and products are: 1.00 g of HgO (s), 2.00 mL of Hg (l), and 1.60 mol/L of O
2
(g). What is the value of the equilibrium constant, Kc? (In case you wish to know, HgO (s) has molar mass 217 g/mol and density 1.10 g/mL, and metallic mercury Hg (l) has atomic mass 201 g/mol and density 13.6 g/mL.)
Equilibrium constant
What is the correct expression for the equilibrium constant of the following reaction? 6 CO
2
(g) + 6 H
2
O (g)
⇌
C
6
H
12
O
6
(s) + 6 O
2
(g)
Equilibrium: ICE Table
A reaction mixture consisting of 0.400 mol H
2
and 1.60 mol I
2
was introduced into a 3.00 L flask and heated. At equilibrium 60% of the hydrogen gas had reacted. What is the equilibrium constant Kc for the reaction H
2
(g) + I
2
(g)
⇌
2 HI (g)?
Equilibrium constant: Kp
Consider the equilibrium reaction: 2 NO
2
(g)
⇌
N
2
O
4
(g)
A container initially holds a mixture of 2.0 atm of N
2
O
4
and 1.0 atm of NO
2
. The system is allowed to equilibrate and it is noticed that the pressure of NO
2
has increased by 0.3 atm. What is the K
p
for this equilibrium?
Equilibrium constant
Which of the following pairs of chemical equation and equilibrium constant expression is/are CORRECT?
1. 4 Bi (s) + 3 O
2
(g)
⇌
2 Bi
2
O
3
(s), K = [O
2
]
3
2. Ba (s) + 2 H
+
(aq)
⇌
Ba
2+
(aq) + H
2
(g), K = [Ba
2+
][H
2
] / [H
+
]
Equilibrium: Equilibrium constant
For the process: PCl
5
(g)
⇌
PCl
3
(g) + Cl
2
(g)
K
c
= 0.040 at 450
o
C. If a reaction is initiated with 0.40 mol of Cl
2
and 0.40 mol of PCl
3
in a 1.0 liter container, what is the equilibrium concentration of Cl
2
in the system?
Equilibrium: Equilibrium constant
For the process: N
2
(g) + 3 H
2
(g)
⇌
2 NH
3
(g)
Determine the value of K
c
when an equilibrium mixture contains 0.0420 mol N
2
, 0.516 mol H
2
, and 0.0357 mol NH
3
in a 1.00 liter container at 400
o
C.
Equilibrium: Equilibrium constant
For the process 2 SO
3
(g)
⇌
2 SO
2
(g) + O
2
(g), the equilibrium constant expression (Kc) is:
Equilibrium: Equilibrium constant
When 1.00 mol of H
2
and 1.00 mol of Br
2
are combined in a 1.00 liter flask and heated to 448
o
C, 0.780 mol of HBr are formed according to the equilibrium process H
2
(g) + Br
2
(g)
⇌
2 HBr (g). What is Kc for this process at 448
o
C?
Equilibrium: Equilibrium Constant
Given the equilibrium information for water below, what is the concentration of hydroxide ions in a solution of 1.5 M HCl?
2 H
2
O (l)
⇌
H
3
O
+
(aq) + OH
-
(aq), K
c
= 1x10
-14
at 20
o
C
Equilibrium: Equilibrium constant
Given the equilibrium information for water below, what is the concentration of hydroxide ions in water?
2 H
2
O (l)
⇌
H
3
O
+
(aq) + OH
-
(aq), K
c
= 1x10
-14
at 20
o
C
Equilibrium: Equilibrium constant
For the equilibrium process NH
4
SH (s)
⇌
NH
3
(g) + H
2
S (g), Kc = 1.2x10
-4
at 218
o
C. What is the equilibrium concentration of NH
3
if a sample of NH
4
SH is allowed to achieve equilibrium at 218
o
C in a sealed rigid vessel?
Equilibrium: Equilibrium constant
For the equilibrium process 2 NO (g) + Br
2
(g)
⇌
2 NOBr (g), the equilibrium constant expression (Kc) is:
Which equilibrium K expression for the reactions shown below is CORRECT?
For the equilibrium process 2 NO (g) + Br
2
(g)
⇌
2 NOBr (g), the equilibrium constant expression (Kc) is:
Equilibrium constant
Equal quantities of hydrogen and gaseous iodine at 700 K (427
o
C) are placed in a reaction vessel and allowed to reach equilibrium according to the following equation:
H
2
(g) + I
2
(g)
⇌
2 HI (g)
If the following equilibrium concentrations are measured: [H
2
] = [I
2
] = 0.021 mol/L and [HI] = 0.158 mol/L, what is the equilibrium constant for this reaction at 700 K?
Equilibrium: Equilibrium constant
If the equilibrium constant for reaction 1 below is K, what is the equilibrium constant for reaction 2?
(1) SO
2
(g) + ½ O
2
(g) ⇌ SO
3
(g)
(2) 2SO
3
(g)
⇌
2 SO
2
(g) + O
2
(g)
Equilibrium: Equilibrium constant
If K
c
= 0.212 at 100
o
C for N
2
O
4
(g)
⇌
2 NO
2
(g)
Determine the value of K
c
at 100
o
C for 2 NO
2
(g)
⇌
N
2
O
4
(g)
Equilibrium Constant
A 400 L reactor is charged with 10.0 moles of ammonia (NH
3
) at 450 K. Over time the ammonia decomposes into it's elements according to the reaction below and at equilibrium the pressure of H
2
is 0.0140 atm. Calculate the equilibrium constant for this reaction.
2
N
H
3
(
g
)
→
3
H
2
(
g
)
+
N
2
(
g
)
2\ NH_{3(g)}\rightarrow 3\ H_{2(g)}+N_{2(g)}
2
N
H
3
(
g
)
→
3
H
2
(
g
)
+
N
2
(
g
)
Equilibrium constant
A reaction is shown below between chlorine gas and iodine gas at 600 K. After the reaction comes to equilibrium the partial pressures are
p
(
C
l
2
)
=
0.438
a
t
m
p
(
I
2
)
=
0.146
a
t
m
p
(
I
C
l
3
(
g
)
)
=
1.767
a
t
m
p(Cl_2)=0.438 \ atm\ \ \ p(I_2)=0.146\ atm \ \ \ \ p(ICl_{3(g)})=1.767\ atm
p
(
C
l
2
)
=
0.438
a
t
m
p
(
I
2
)
=
0.146
a
t
m
p
(
I
C
l
3
(
g
)
)
=
1.767
a
t
m
3
C
l
2
(
g
)
+
I
2
(
g
)
→
2
I
C
l
3
(
g
)
3\ Cl_{2(g)}+I_{2(g)}\rightarrow 2\ ICl_{3(g)}
3
C
l
2
(
g
)
+
I
2
(
g
)
→
2
I
C
l
3
(
g
)
For an experiment involving the Haber’ process,
N
2
(
g
)
+
3
H
2
(
g
)
⇋
2
N
H
3
(
g
)
N_{2(g)}+3H_{2(g)} \leftrightharpoons 2NH_{3(g)}
N
2
(
g
)
+
3
H
2
(
g
)
⇋
2
N
H
3
(
g
)
The initial concentrations were: [N
2
] = 3.00 M, [H
2
] = 4.00 M and [NH
3
] = 1.00 M. After some time, the concentration of H
2
was found to be 2.80 M. What was the concentration of NH
3
at this time?
If an endothermic equilibrium reaction has a K value of 3.4 at room temperature, which of the following statements is correct?
Consider the following equilibrium:
Br
2
(g) + Cl
2
(g) ⇌ 2 BrCl (g) at 400 K, K
c
= 7.0
If 0.20 M of Br
2
(g) and 0.20 M of Cl
2
(g) are placed in a vessel and heated to 400 K, what is the equilibrium concentrations of BrCl (g)?
At 450 K, the equilibrium constant in terms of pressure,
C
O
(
g
)
+
H
2
O
(
g
)
→
H
2
(
g
)
+
C
O
2
(
g
)
K
p
=
34.7
C
H
4
(
g
)
+
O
2
→
C
O
2
(
g
)
+
2
H
2
(
g
)
K
p
=
119.2
\begin{array}{cc} CO_{(g)}+H_2O_{(g)}\rightarrow H_{2(g)}+CO_{2(g)} & K_p=34.7 \\ CH_{4(g)}+O_{2}\rightarrow CO_{2(g)}+2\ H_2{(g)} & K_p=119.2 \end{array}
C
O
(
g
)
+
H
2
O
(
g
)
→
H
2
(
g
)
+
C
O
2
(
g
)
C
H
4
(
g
)
+
O
2
→
C
O
2
(
g
)
+
2
H
2
(
g
)
K
p
=
34.7
K
p
=
119.2
What is K
p
for the following reactio at 450 K?
The equilibrium constant, Kc, for the following reaction below was measured at 7.7.
S
O
3
(
g
)
+
N
O
(
g
)
⇌
N
O
2
(
g
)
+
S
O
2
(
g
)
SO_{3}(g)+NO(g)\rightleftharpoons NO_{2}(g)+SO_{2}(g)
S
O
3
(
g
)
+
N
O
(
g
)
⇌
N
O
2
(
g
)
+
S
O
2
(
g
)
At the same temperature the measurement was taken, a mixture of 0.4 M SO
3
and 0.4 M NO was generated. After allowing the system to reach equilibrium what is the concentration of SO
2
?
Equilibrium constant
At a certain temperature, the value of the equilibrium constant for the following reaction is
Kc = 100. N
2
(g) + 2 O
2
(g)
⇌
2 NO
2
(g)
What is the equilibrium constant for the following reaction?
Equilibrium constant
Which of the following substances present in a chemical reaction would NOT normally be included in the equilibrium constant expression?
Equilibrium: ICE Table
Cyclohexane (C
6
H
12
) undergoes an isomerization in the presence of the appropriate catalyst to form a compound called MCP.
C
6
H
12
(g)
⇌
MCP (g) K
c
= 0.143 at 25
o
C
The initial concentrations are [C
6
H
12
] = 0.800 M and [MCP] = 0.100 M. What are the equilibrium concentrations of these two compounds?
Equilibrium: ICE Table
A mixture of 0.682 mol of H
2
and 0.440 mol of Br
2
combined in a reaction vessel with a volume of 2.00 L achieves equilibrium at 700 K according to the equation below. At equilibrium, there are 0.556 mol of H
2
present. How many moles of Br
2
are present at equilibrium?
H
2
(g) + Br
2
(g)
⇌
2 HBr (g)
For a specific reaction, which of the following statements about the equilibrium constant is true?
Equilibrium: Equilibrium Constant
For the equilibrium process 2 SO
3
(g)
⇌
2 SO
2
(g) + O
2
(g), determine the value of K
c
when an equilibrium mixture contains 0.025 mol O
2
, 0.27 mol SO
2
, and 0.018 mol SO
3
in a 5.00 liter container at 220
o
C.
For the process: N
2
(g) + 3 H
2
(g) ⇌ 2 NH
3
(g)
Determine the value of K
c
when an equilibrium mixture contains 0.0420 mol N
2
, 0.516 mol H
2
, and 0.0357 mol NH
3
in a 1.00 liter container at 400
o
C.
Which of the following expression is the correct equilibrium-constant expression for the reaction below?
HF
(aq)
+ H
2
O
(l)
⇌ H
3
O
+
(aq)
+ F
-
(aq)
1.
For the equilibrium process 2 NO (g) + Br
2
(g) ⇌ 2 NOBr (g), the equilibrium constant expression (Kc) is:
Equilibrium Constant
A one liter vessel was filled with 0.398 mol of NOCl(g). Then the temperature of the system was increased to 245 °C to undergo the following reaction:
2
N
O
C
l
(
g
)
⇌
2
N
O
(
g
)
+
C
l
2
(
g
)
2NOCl(g) \rightleftharpoons 2NO(g) +Cl_2(g)
2
N
O
C
l
(
g
)
⇌
2
N
O
(
g
)
+
C
l
2
(
g
)
When equilibrium was attained, the concentration of Cl
2
was 0.0225 mol/liter. Calculate the value of K
c
at 245 °C for the reaction.
Equilibrium
Consider the following equilibria:
2
H
C
l
(
g
)
⇌
H
2
(
g
)
+
C
l
2
(
g
)
K
c
,
1
2HCl_{(g)} \rightleftharpoons H_{2(g)} +Cl_2{(g)} \hspace{20pt} K_c,1
2
H
C
l
(
g
)
⇌
H
2
(
g
)
+
C
l
2
(
g
)
K
c
,
1
2
H
2
S
2
(
g
)
⇌
2
H
2
(
g
)
+
S
2
(
g
)
K
c
,
2
2H_2S_2{(g)} \rightleftharpoons 2H_{2(g)} +S_2{(g)} \hspace{20pt} K_c,2
2
H
2
S
2
(
g
)
⇌
2
H
2
(
g
)
+
S
2
(
g
)
K
c
,
2
Equilibrium: Equilibrium constant
For the equilibrium process NH
4
SH (s) ⇌ NH
3
(g) + H
2
S (g), K
c
= 1.2x10
-4
at 218
o
C. What is the equilibrium concentration of NH
3
if a sample of NH
4
SH is allowed to achieve equilibrium at 218
o
C in a sealed rigid vessel?
Equilibrium: Equilibrium Constant
For the equilibrium process 2 SO
3
(g) ⇌ 2 SO
2
(g) + O
2
(g), determine the value of Kc when an equilibrium mixture contains 0.025 mol O
2
, 0.27 mol SO
2
, and 0.018 mol SO
3
in a 5.00 liter container at 220
o
C.
Equilibrium constant
A 1.0 L flask was loaded and the system was allowed to reach equilibrium at 25 °C. The equilibrium mixture was found to contain: 1.5 mol Cr (S), 1.5 mol CCI
4
(g), 2.3 mol CrCl
3
, (g), and 2.5 mol C (S). Determine the K
c
value for this reaction at 25 °C.
Equilibrium: Magnitude of Equilibrium Constants
The value of K
C
for the reaction below is 1.2×10
‐42
at 500 K.
H
2
(
g
)
⇌
2
H
(
g
)
H_2 (g)⇌2H(g)
H
2
(
g
)
⇌
2
H
(
g
)
Which of the following statements is true when the reaction is at equilibrium?
Which answer below correctly describes the calculation to find the equilibrium expression K
4
?
C
H
4
(
g
)
+
H
2
O
(
g
)
⇌
C
O
(
g
)
+
3
H
2
(
g
)
K
1
C
H
4
(
g
)
+
2
S
2
(
g
)
⇌
C
S
2
(
g
)
+
2
H
2
S
(
g
)
K
2
C
O
2
(
g
)
+
H
2
(
g
)
⇌
C
O
(
g
)
+
H
2
O
(
g
)
K
3
C
S
2
(
g
)
+
2
H
2
S
(
g
)
+
3
C
O
2
(
g
)
⇌
4
C
O
(
g
)
+
2
S
2
(
g
)
+
2
H
2
O
(
g
)
K
4
\def\arraystretch{1.5} \begin{array}{c:c} CH_4 (g)+H_2 O(g)⇌CO(g)+3H_2 (g) & K_1 \\ CH_4 (g)+2S_2 (g)⇌CS_2 (g)+2H_2 S(g) & K_2\\ CO_2 (g)+H_2 (g)⇌CO(g)+H_2 O(g) & K_3\\ CS_2 (g)+2H_2 S(g)+3CO_2 (g)⇌4CO(g)+2S_2 (g)+2H_2 O(g) & K_4 \end{array}
C
H
4
(
g
)
+
H
2
O
(
g
)
⇌
C
O
(
g
)
+
3
H
2
(
g
)
C
H
4
(
g
)
+
2
S
2
(
g
)
⇌
C
S
2
(
g
)
+
2
H
2
S
(
g
)
C
O
2
(
g
)
+
H
2
(
g
)
⇌
C
O
(
g
)
+
H
2
O
(
g
)
C
S
2
(
g
)
+
2
H
2
S
(
g
)
+
3
C
O
2
(
g
)
⇌
4
C
O
(
g
)
+
2
S
2
(
g
)
+
2
H
2
O
(
g
)
K
1
K
2
K
3
K
4
Equilibrium Constant
If 1.00 mole of HCl (g) is placed in an 8.00 L container, what will be the concentration of H
2
in that container at equilibrium?
2
H
C
l
(
g
)
⇌
H
2
(
g
)
+
C
l
2
(
g
)
K
C
=
1.3
×
10
−
9
2HCl(g)⇌H_2 (g)+Cl_2 (g) \qquad K_C=1.3×10^{-9}
2
H
C
l
(
g
)
⇌
H
2
(
g
)
+
C
l
2
(
g
)
K
C
=
1.3
×
1
0
−
9
Equilibrium Constant
Carbon disulfide, CS
2
, and chlorine gas react according to the following equation:
C
S
2
(
g
)
+
3
C
l
2
(
g
)
⇌
S
2
C
l
2
(
g
)
+
C
C
l
4
(
g
)
CS_2 (g)+3Cl_2 (g)⇌ S_2 Cl_2 (g)+CCl_4 (g)
C
S
2
(
g
)
+
3
C
l
2
(
g
)
⇌
S
2
C
l
2
(
g
)
+
C
C
l
4
(
g
)
When 1.00 mol of CS
2
and 3.00 mol of Cl
2
are placed in a 2.00 L container and allowed to come to equilibrium, the mixture is found to contain 0.250 mol of CCl
4
. What is the amount of Cl
2
at equilibrium?
Equilibrium: Calculating Equilibrium Concentrations
Iodine chloride (ICl) can decompose, forming iodine and chlorine gases. If a reaction vessel is prepared by filling a 5.00 L container with 0.500 mol each of ICl, I
2
, and Cl
2
.
2
I
C
l
(
g
)
⇌
I
2
(
g
)
+
C
l
2
(
g
)
K
C
=
0.110
(
a
t
25
°
C
)
2ICl(g)⇌I_2 (g)+Cl_2 (g)\qquad K_C = 0.110\ (at \ 25°C)
2
I
C
l
(
g
)
⇌
I
2
(
g
)
+
C
l
2
(
g
)
K
C
=
0.110
(
a
t
25°
C
)
a) In which direction will the reaction proceed (towards products or reactants)? Show how you determined your answer.
Equilibrium Constant
Given the following information:
N
i
(
O
H
)
2
(
s
)
⇌
N
i
2
+
(
a
q
)
+
2
O
H
−
(
a
q
)
K
s
p
=
6.0
×
10
−
16
H
2
O
(
l
)
⇌
H
+
(
a
q
)
+
O
H
−
(
a
q
)
K
w
=
1.0
×
10
−
14
\def\arraystretch{1.5}\begin {array}{cc}Ni(OH)_2 (s) ⇌Ni^{2+} (aq)+2OH^- (aq)&&K_{sp}= 6.0 ×10^{-16}\\ H_2 O(l) ⇌H^+ (aq)+OH^- (aq) &&K_w= 1.0×10^{-14}\end{array}
N
i
(
O
H
)
2
(
s
)
⇌
N
i
2
+
(
a
q
)
+
2
O
H
−
(
a
q
)
H
2
O
(
l
)
⇌
H
+
(
a
q
)
+
O
H
−
(
a
q
)
K
s
p
=
6.0
×
1
0
−
16
K
w
=
1.0
×
1
0
−
14
What is the equilibrium constant for the reaction,
Equilibrium: Equilibrium constant
At 25 ˚C, K
P
= 5.2 × 10
–2
for the following decomposition reaction:
N
H
4
H
S
(
s
)
⇌
N
H
3
(
g
)
+
H
2
S
(
g
)
NH_4HS(s)⇌NH_3(g)+H_2S(g)
N
H
4
H
S
(
s
)
⇌
N
H
3
(
g
)
+
H
2
S
(
g
)
Given the following information at 298 K:
S
n
O
2
(
s
)
+
2
H
2
(
g
)
⇌
S
n
(
s
)
+
2
H
2
O
(
g
)
K
1
=
8.12
H
2
(
g
)
+
C
O
2
(
g
)
⇌
H
2
O
(
g
)
+
C
O
(
g
)
K
2
=
0.771
\def\arraystretch{1.5} \begin{array}{cc} SnO_2 (s) + 2 H_2 (g) ⇌ Sn (s) + 2 H_2 O (g) & K_1 = 8.12 \\ H_2 (g) + CO_2 (g) ⇌ H_2 O (g) + CO (g) &K_2 = 0.771 \end{array}
S
n
O
2
(
s
)
+
2
H
2
(
g
)
⇌
S
n
(
s
)
+
2
H
2
O
(
g
)
H
2
(
g
)
+
C
O
2
(
g
)
⇌
H
2
O
(
g
)
+
C
O
(
g
)
K
1
=
8.12
K
2
=
0.771
Determine the
K
for the overall reaction:
S
n
O
2
(
s
)
+
2
C
O
(
g
)
⇌
S
n
(
s
)
+
2
C
O
2
(
g
)
.
SnO_2 (s) + 2 CO (g) ⇌ Sn (s) + 2 CO_2 (g).
S
n
O
2
(
s
)
+
2
C
O
(
g
)
⇌
S
n
(
s
)
+
2
C
O
2
(
g
)
.
Use the following information for
both
of the next two questions
We can easily observe shifts in the equilibrium of the following reaction because the reactants and products have different colours.
2
N
O
2
(
g
)
⇌
N
2
O
4
(
g
)
D
a
r
k
r
e
d
C
o
l
o
u
r
l
e
s
s
\def\arraystretch{1.5} \begin{array}{ccc} &2NO_2(g)&⇌&N_2O_4(g) \\ &\rm Dark \ red && \rm Colourless \end{array}
2
N
O
2
(
g
)
Dark
red
⇌
N
2
O
4
(
g
)
Colourless
Chemical Equilibria
Consider this balanced chemical reaction and the molecular representation for both of the next two questions:
2
A
B
(
g
)
⇌
A
2
(
g
)
+
B
2
(
g
)
2AB(g)⇌A_2(g)+B_2(g)
2
A
B
(
g
)
⇌
A
2
(
g
)
+
B
2
(
g
)
The following equilibrium concentrations were observed in the synthesis of NH
3
at
127
o
C
:
[
N
H
3
]
=
3.1
×
10
−
2
M
;
[
N
2
]
=
8.5
×
10
−
1
M
;
[
H
2
]
=
3.1
×
10
−
3
M
127^oC:[NH_3]=3.1\times 10^{-2} M; [N_2]=8.5\times 10^{-1} M; [H_2]=3.1\times 10^{-3}M
12
7
o
C
:
[
N
H
3
]
=
3.1
×
1
0
−
2
M
;
[
N
2
]
=
8.5
×
1
0
−
1
M
;
[
H
2
]
=
3.1
×
1
0
−
3
M
The balanced reaction is: N2 + 3H2 -eqm> NH3
Which of the graphs below could correctly illustrate the outcome of the reaction?
2
B
r
C
l
⇌
C
l
2
+
B
r
2
2BrCl \rightleftharpoons Cl_2+Br_2
2
B
r
C
l
⇌
C
l
2
+
B
r
2
K
c
=
5.0
K_c=5.0
K
c
=
5.0
Equilibrium: ICE Table
A sample of 0.0015 moles of F
2
was sealed into a 1.0 L reaction vessel and heated to 1000. K to study the dissociation into F atoms:
F
2
⇌
2
F
K
c
=
1.2
×
10
−
4
F_2 \rightleftharpoons 2F\ \ \ \ \ \ \ \ K_c=1.2\times 10^{-4}
F
2
⇌
2
F
K
c
=
1.2
×
1
0
−
4
What are [F
2
] and [F] at equilibrium?
Equilibrium: Reaction Quotient
Silver chloride will react with acetic acid to form the complex ion silver acetate. A reaction mixture is prepared by adding 0.25 g of AgCl to a 1.25 L solution that already contains 4.6×10
‐6
M Ag(CH
3
COO)(aq), 2.3×10
‐3
M Cl
-
, 1.1×10
‐8
M H
+
, and 0.010M CH
3
COOH. Based on this information, which of the statements below is true?
A
g
C
l
(
s
)
+
C
H
3
C
O
O
H
(
a
q
)
⇌
A
g
(
C
H
3
C
O
O
)
(
a
q
)
+
C
l
−
(
a
q
)
+
H
+
(
a
q
)
K
=
5.87
×
10
−
16
AgCl(s)+CH_3 COOH(aq)⇌Ag(CH_3 COO)(aq)+Cl^- (aq)+H^+ (aq)\qquad K = 5.87×10^{-16}
A
g
C
l
(
s
)
+
C
H
3
C
O
O
H
(
a
q
)
⇌
A
g
(
C
H
3
C
O
O
)
(
a
q
)
+
C
l
−
(
a
q
)
+
H
+
(
a
q
)
K
=
5.87
×
1
0
−
16
After allowing this solution to rest for some time:
The reaction for the reforming of methane from steam is given by:
C
H
4
(
g
)
+
H
2
O
(
g
)
⇌
C
O
(
g
)
+
3
H
2
(
g
)
CH_4(g)+H_2O(g)⇌CO(g)+3H_2(g)
C
H
4
(
g
)
+
H
2
O
(
g
)
⇌
C
O
(
g
)
+
3
H
2
(
g
)
A closed reaction vessel starts with initial concentrations of 1.00 M for every gas. After reaching equilibrium at a particular temperature, the final CO concentration was measured to be 0.80 M. Determine K
C
for this reaction at this temperature.