CHMI 11600 PARTÉ Week 5 Chemical Equilibrium (17.5-17.6)

• 0.095 atm

• 0.23 atm

• 0.33 atm

• 0.54 atm

• 0.77 atm

At high temperature, carbon reacts with O₂ to produce CO.

C(s) + O₂(g) ⇌ 2CO(g)

When 0.350 mol of O₂ and excess carbon were placed in a 5.00-L container and heated, the equilibrium concentration of CO was found to be 0.060 M. Calculate the value of the equilibrium constant, Kc, for this reaction.

• 0.010

• 0.072

• 0.090

• 0.17

• 1.2

Solid ammonium iodide (NH4I) decomposes to ammonia and hydrogen iodide at 400°C according to the following equation: NH4I(s) ⇌ NH3(g) + HI(g), Kp = 0.215. If 55.0 g of NH4I(s) is placed in a sealed 5.0-L container at 400°C, calculate the partial pressure (in atm) of ammonia at equilibrium.

• 0.103 atm

• 0.215 atm

• 0.232 atm

• 0.464 atm

• 2.00 atm

The following reaction in a 1.0-L flask is initially at equilibrium with concentrations of [HI] = 1.22 M, [H2] = 0.300 M, and [I2] = 0.100 M. 2HI(g) ⇌ H2(g) + I2(g). An additional 0.200 mol of I2(g) is added to the flask, and the reaction is then allowed to reestablish equilibrium. Calculate the concentration of HI(g) (in M) once equilibrium has been reestablished.

• 0.100 M

• 0.661 M

• 1.02 M

• 1.32 M

• 1.42 M

For which of the following reactions would the equilibrium concentrations NOT be affected by a change in the pressure resulting from a change in the volume of the container?

• N2(g) + 3H2(g) ⇌ 2NH3(g)

• PCl3(g) + Cl2(g) ⇌ PCl5(g)

• 2NO2(g) ⇌ N2(g) + 2O2(g)

• CO(g) + 1/2O2(g) ⇌ CO2(g)

• CO(g) + H2O(g) ⇌ CO2(g) + H2(g)

Commercially, ammonia (NH3) is produced from nitrogen (N2) and hydrogen (H2) using the Haber process: N2(g) + 3H2(g) ⇌ 2NH3(g). This reaction is exothermic. Which of the following would INCREASE the amount of NH3 obtained (i.e., maximize the yield of NH3) at equilibrium?

• Decrease the pressure.

• Increase the temperature.

• Increase the concentration of N2.

• Increase the concentration of NH3.

• Decrease the concentration of H2.

If the following reaction were at equilibrium, N2(g) + 3H2(g) rightleftharpoons 2NH3(g), Kc = 60, then removal of ammonia by condensation would cause:

• the concentrations of H2 and N2 to increase.

• the concentrations of H2 and N2 to decrease.

• the concentration of H2 to increase and the concentration of N2 to decrease.

• the concentration of H2 to decrease and the concentration of N2 to increase.

• no change in the concentrations of H2 and N2.

The Haber-Bosch process is used to prepare ammonia, N2(g) + 3H2(g) rightleftharpoons 2NH3(g), ΔH = -92.4 kJ. Industrially, this reaction is performed at temperatures ranging from 400°C to 650°C. The high temperatures used in this process cause:

• the value of Kc to increase, and the rate of the reaction to decrease.

• the value of Kc to increase, and the rate of the reaction to increase.

• the value of Kc to decrease, and the rate of the reaction to decrease.

• the value of Kc to decrease, and the rate of the reaction to increase.

• no change in either the value for Kc or the rate of the reaction.

• The net driving force for the reaction will always be left to right because the equilibrium constant is very large.

• The rate of the forward reaction will always be greater than the rate of the reverse reaction because the equilibrium constant is so large.

• For a reaction mixture containing equilibrium concentrations of the three components, the forward and reverse rates will both go to zero.

• All responses above are correct.

• All responses above are incorrect.

Consider the following exothermic gas-phase reaction, 4HCl(g) + O2(g) ⇌ 2Cl2(g) + 2H2O(g) ΔH = -113 kJ. Assuming that the system is initially at equilibrium, describe what will happen to the number of moles of HCl(g) in a container of fixed volume if: (a) O2(g) is added to the system. (b) Cl2(g) is added to the system. (c) some of the H2O(g) is removed from the system. (d) the temperature is increased. (e) the pressure is increased.

• O2(g) is added

• Cl2(g) is added

• H2O(g) is removed

• Temperature is increased

• Pressure is increased