Question 1

Consider the equilibrium equation C(s) + H2O(g) ⇌ CO(g) + H2(g), $\Delta$H = 2296 J. The reaction will shift towards products if the volume of the container is decreased.

Accepted Answer

A) True 
 B)False  False

Question 2

Which of the following rate laws is consistent with the following mechanism
A2(g) + C(g) ⇌ AC(g) + A(g) fast equilibrium (Kc1)
AC(g) + B2(g) $\rarr$ AB2(g) + C(g) slow

Accepted Answer

A)   Rate = k[A2][C]
B)   Rate = k[AB2][C]/[AC][B2]
C)   Rate = kKc1[A2][C][B2]/[A]
D)   Rate = [A][AB2]/[A2][B2]
E)   Rate = kKc1[AC][A]/[A2][C]  C

Question 3

At 340 K, Kp = 69 for the reaction H2(g) + I2(g) (⇌) 2HI(g). 50.0 g of HI is injected into an evacuated 5.00-L rigid cylinder at 340 K. What is the total pressure inside the cylinder when the system comes to equilibrium

Accepted Answer

A)   2.60 atm
B)   1.76 atm
C)   0.424 atm
D)   2.18 atm
E)   10.9 atm D

Question 4

25.0 g of HI(g) is injected into a 4.00 L reaction vessel that contains 20.0 g of I2(g). When the system comes to equilibrium at 400ºC, what will be the total pressure inside the reaction vessel?
2HI(g) ⇌ H2(g) + I2(g), Kc = 0.0156 at 400ºC

Accepted Answer

A)   2.70 atm
B)   13.0 atm
C)   2.43 atm
D)   0.815 atm
E)   3.24 atm

Question 5

The brown gas NO2 and the colorless gas N2O4 exist in equilibrium, 2NO2 $\rightleftharpoons$N2O4. In an experiment, 0.625 mole of N2O4 was introduced into a 5.00 L vessel and was allowed to decompose until equilibrium was reached. The concentration of N2O4 at equilibrium was 0.0750 M. Calculate Kc for the reaction.

Accepted Answer

A)   7.5
B)   0.125
C)   0.0750
D)   0.10
E)   0.050

Question 6

If the reaction 2H2S(g) ⇌ 2H2(g) + S2(g) is carried out at 1065$\circ$C, Kp = 0.0120. Starting from pure H2S introduced into an evacuated vessel at 1065$\circ$C, what will the total pressure in the vessel be at equilibrium if the equilibrated mixture contains 0.300 atm of H2(g)

Accepted Answer

A)   1.06 atm
B)   1.36 atm
C)   2.39 atm
D)   4.20 atm
E)   1.51 atm

Question 7

Calculate Kp for the reaction 2NOCl(g) $\rightleftharpoons$ 2NO(g) + Cl2(g) at 400$\circ$C if Kc at 400$\circ$C for this reaction is 2.1 * 10-2.

Accepted Answer

A)   2.1 * 10-2
B)   1.7 * 10-3
C)   0.70
D)   1.2
E)   3.8 * 10-4

Question 8

Consider the reaction, N2(g) + 3H2(g) ⇌ 2NH3(g). Kc = 4.2 at 600 K.What is the value of Kc for 4 NH3(g) ⇌ 2N2(g) + 6H2(g)

Accepted Answer

A)   0.053
B)   0.055
C)   0.057
D)   0.059
E)   None of the above

Question 9

For the following reaction at equilibrium in a reaction vessel, which one of these changes would cause the Br2 concentration to increase
2NOBr(g) ⇌ 2NO(g) + Br2(g), $\Delta$Hºrxn= 30 kJ/mol

Accepted Answer

A)   Lower the temperature.
B)   Remove some NO.
C)   Remove some NOBr.
D)   Compress the gas mixture into a smaller volume.
E)   Add a catalyst

Question 10

For the following reaction at equilibrium, which gives a change that will shift the position of equilibrium to favor formation of more products
2NOBr(g) ⇌ 2NO(g) + Br2(g), $\Delta$Hºrxn = 30 kJ/mol

Accepted Answer

A)   Increase the total pressure by decreasing the volume.
B)   Add more NO.
C)   Remove Br2.
D)   Lower the temperature.
E)   Remove NOBr selectively.

Question 11

The data below refer to the following reaction: 2NO(g) + Br2(g) ⇌ 2NOBr(g) $\begin{array}{lccc}
\text { Concentration (M) } & [\mathrm{NO}] & \left[\mathrm{Br}_{2}\right] & {[\mathrm{NOBr}]} \
\hline \text { Initial } & 2.5 & 5.0 & 1.0 \
\text { Equilibrium } & 2.0 & - & -
\end{array}$ Calculate Kc.

Accepted Answer

A)   0.080
B)   0.10
C)   0.12
D)   0.14
E)   None of the above

Question 12

Sodium carbonate, Na2CO3(s), can be prepared by heating sodium bicarbonate, NaHCO3(s) as shown below.2NaHCO3(s) (⇌) Na2CO3(s) + CO2(g) + H2O(g) Kp = 0.23 at 100ºC If a sample of NaHCO3 is placed in an evacuated flask and allowed to achieve equilibrium at 100ºC, what will the total gas pressure be

Accepted Answer

A)   0.46 atm
B)   0.96 atm
C)   0.23 atm
D)   0.48 atm
E)   0.11 atm

Question 13

On analysis, an equilibrium mixture for the reaction 2H2S(g) $\rightleftharpoons$2H2(g) + S2(g) was found to contain 1.0 mol H2S, 4.0 mol H2, and 0.80 mol S2 in a 4.0 L vessel. Calculate the equilibrium constant, Kc, for this reaction.

Accepted Answer

A)   1.6
B)   3.2
C)   12.8
D)   0.64
E)   0.8

Question 14

Consider the reaction N2(g) + 3H2(g) ⇌ 2NH3(g). Using a catalyst will cause the reaction to shift to the right.

Accepted Answer

A) True 
 B)False

Question 15

The equilibrium between carbon dioxide gas and carbonic acid is very important in biology and environmental science, and is shown below.CO2(aq) + H2O(l) ⇌ H2CO3(aq)
Based on the equilibrium constant reported for this reaction (Kc = 1.70 * 10-3), there will be more carbon dioxide in solution than carbonic acid.

Accepted Answer

A) True 
 B)False

Question 16

15.00 g of solid ammonium hydrogen sulfide is introduced into a 500.-mL flask at 25$\circ$C, the flask is sealed, and the system is allowed to reach equilibrium. What is the partial pressure of ammonia in this flask if Kp = 0.108 at 25$\circ$C for NH4HS(s) ⇌ NH3(g) + H2S (g)

Accepted Answer

A)   0.657 atm
B)   1.25 atm
C)   0.329 atm
D)   14.4 atm
E)   2.50 atm

Question 17

50.0 g of N2O4 is introduced into an evacuated 2.00 L vessel and allowed to come to equilibrium with its decomposition product, N2O4(g) ⇌ 2NO2(g). For this reaction Kc = 0.133. Once the system has reached equilibrium, 5.00 g of NO2 is injected into the vessel, and the system is allowed to equilibrate once again. Calculate the mass of NO2 in the final equilibrium mixture.

Accepted Answer

A)   17.8 g
B)   12.4 g
C)   14.7 g
D)   19.7 g
E)   15.5 g

Question 18

The data below refer to the following reaction: 2NO(g) + Br2(g) ⇌ 2NOBr(g) $\begin{array}{lccc}
\text { Concentration (M) } & [\mathrm{NO}] & \left[\mathrm{Br}_{2}\right] & {[\mathrm{NOBr}]} \
\hline \text { Initial } & 2.5 & 5.0 & 1.0 \
\text { Equilibrium } & 2.0 & - & -
\end{array}$ Find the concentration of NOBr when the system reaches equilibrium.

Accepted Answer

A)   1.1 M
B)   1.3 M
C)   1.5 M
D)   1.7 M
E)   None of the above

Question 19

The reaction 2SO3(g) ⇌2SO2(g) + O2(g) is endothermic. If the temperature is increased,

Accepted Answer

A)   more SO3 will be produced.
B)   Kc will decrease.
C)   no change will occur in Kc .
D)   Kc will increase.
E)   the pressure will decrease.

Question 20

Calcium carbonate decomposes at high temperatures to give calcium oxide and carbon dioxide as shown below.CaCO3(s) ⇌ CaO(s) + CO2(g) The KP for this reaction is 1.16 at 800$\circ$C. A 5.00 L vessel containing 10.0 g of CaCO3(s) was evacuated to remove the air, sealed, and then heated to 800$\circ$C. Ignoring the volume occupied by the solid, what will be the mass of the solid in the vessel once equilibrium is reached

Accepted Answer

A)   6.9 g of solid
B)   7.1 g of solid
C)   7.3 g of solid
D)   7.5 g of solid
E)   None of the above

Exam 14: Chemical Equilibrium

Consider the equilibrium equation C(s) + H₂O(g) ⇌ CO(g) + H₂(g), $\Delta$ H = 2296 J. The reaction will shift towards products if the volume of the container is decreased.

Which of the following rate laws is consistent with the following mechanism A₂(g) + C(g) ⇌ AC(g) + A(g) fast equilibrium (K_c1) AC(g) + B₂(g) $\rarr$ AB₂(g) + C(g) slow

At 340 K, K_p = 69 for the reaction H₂(g) + I₂(g) (⇌) 2HI(g) . 50.0 g of HI is injected into an evacuated 5.00-L rigid cylinder at 340 K. What is the total pressure inside the cylinder when the system comes to equilibrium

25.0 g of HI(g) is injected into a 4.00 L reaction vessel that contains 20.0 g of I₂(g) . When the system comes to equilibrium at 400ºC, what will be the total pressure inside the reaction vessel? 2HI(g) ⇌ H₂(g) + I₂(g) , K_c = 0.0156 at 400ºC

If the reaction 2H₂S(g) ⇌ 2H₂(g) + S₂(g) is carried out at 1065^$\circ$C, K_p = 0.0120. Starting from pure H₂S introduced into an evacuated vessel at 1065^$\circ$C, what will the total pressure in the vessel be at equilibrium if the equilibrated mixture contains 0.300 atm of H₂(g)

Calculate K_p for the reaction 2NOCl(g) $\rightleftharpoons$ 2NO(g) + Cl₂(g) at 400^$\circ$C if K_c at 400^$\circ$C for this reaction is 2.1 * 10^-2.

Consider the reaction, N₂(g) + 3H₂(g) ⇌ 2NH₃(g) . K_c = 4.2 at 600 K.What is the value of K_c for 4 NH₃(g) ⇌ 2N₂(g) + 6H₂(g)

For the following reaction at equilibrium in a reaction vessel, which one of these changes would cause the Br₂ concentration to increase 2NOBr(g) ⇌ 2NO(g) + Br₂(g) , $\Delta$ Hº_rxn= 30 kJ/mol

For the following reaction at equilibrium, which gives a change that will shift the position of equilibrium to favor formation of more products 2NOBr(g) ⇌ 2NO(g) + Br₂(g) , $\Delta$ Hº_rxn = 30 kJ/mol

On analysis, an equilibrium mixture for the reaction 2H₂S(g) $\rightleftharpoons$ 2H₂(g) + S₂(g) was found to contain 1.0 mol H₂S, 4.0 mol H₂, and 0.80 mol S₂ in a 4.0 L vessel. Calculate the equilibrium constant, K_c, for this reaction.

Consider the reaction N₂(g) + 3H₂(g) ⇌ 2NH₃(g). Using a catalyst will cause the reaction to shift to the right.

15.00 g of solid ammonium hydrogen sulfide is introduced into a 500.-mL flask at 25^$\circ$C, the flask is sealed, and the system is allowed to reach equilibrium. What is the partial pressure of ammonia in this flask if K_p = 0.108 at 25^$\circ$C for NH₄HS(s) ⇌ NH₃(g) + H₂S (g)

The reaction 2SO₃(g) ⇌2SO₂(g) + O₂(g) is endothermic. If the temperature is increased,

Exam 14: Chemical Equilibrium

Consider the equilibrium equation C(s) + H2O(g) ⇌ CO(g) + H2(g), Δ\DeltaΔ H = 2296 J. The reaction will shift towards products if the volume of the container is decreased.

Which of the following rate laws is consistent with the following mechanism A2(g) + C(g) ⇌ AC(g) + A(g) fast equilibrium (Kc1) AC(g) + B2(g) →\rarr→ AB2(g) + C(g) slow

At 340 K, Kp = 69 for the reaction H2(g) + I2(g) (⇌) 2HI(g) . 50.0 g of HI is injected into an evacuated 5.00-L rigid cylinder at 340 K. What is the total pressure inside the cylinder when the system comes to equilibrium

25.0 g of HI(g) is injected into a 4.00 L reaction vessel that contains 20.0 g of I2(g) . When the system comes to equilibrium at 400ºC, what will be the total pressure inside the reaction vessel? 2HI(g) ⇌ H2(g) + I2(g) , Kc = 0.0156 at 400ºC

If the reaction 2H2S(g) ⇌ 2H2(g) + S2(g) is carried out at 1065 ∘\circ∘ C, Kp = 0.0120. Starting from pure H2S introduced into an evacuated vessel at 1065 ∘\circ∘ C, what will the total pressure in the vessel be at equilibrium if the equilibrated mixture contains 0.300 atm of H2(g)

Calculate Kp for the reaction 2NOCl(g) ⇌\rightleftharpoons⇌ 2NO(g) + Cl2(g) at 400 ∘\circ∘ C if Kc at 400 ∘\circ∘ C for this reaction is 2.1 * 10-2.

Consider the reaction, N2(g) + 3H2(g) ⇌ 2NH3(g) . Kc = 4.2 at 600 K.What is the value of Kc for 4 NH3(g) ⇌ 2N2(g) + 6H2(g)

For the following reaction at equilibrium in a reaction vessel, which one of these changes would cause the Br2 concentration to increase 2NOBr(g) ⇌ 2NO(g) + Br2(g) , Δ\DeltaΔ Hºrxn= 30 kJ/mol

For the following reaction at equilibrium, which gives a change that will shift the position of equilibrium to favor formation of more products 2NOBr(g) ⇌ 2NO(g) + Br2(g) , Δ\DeltaΔ Hºrxn = 30 kJ/mol

On analysis, an equilibrium mixture for the reaction 2H2S(g) ⇌\rightleftharpoons⇌ 2H2(g) + S2(g) was found to contain 1.0 mol H2S, 4.0 mol H2, and 0.80 mol S2 in a 4.0 L vessel. Calculate the equilibrium constant, Kc, for this reaction.