TEXT Chemical Equilibrium Quiz

Consider the following equilibrium: PCl5(g) ⇌ PCl3(g) + Cl2(g). Which of the following will cause a shift in the equilibrium to the left?

• Add more PCl5(g)

• Increase the pressure

• Remove some Cl2(g)

• All of the above

Consider the following equilibrium: H2(g) + I2(g) ⇌ 2HI(g). Which of the following is the proper Keq expression?

• [H₂] [I₂] / [HI]²

• [H₂] [I₂] / 2[HI]

• [HI]² / [H₂] [I₂]

• [HI]² / [H₂] [I₂]

Nitric oxide, NO, is a significant pollutant in the air and is formed at high temperatures in an automobile engine, when oxygen gas and nitrogen gas react. The equilibrium reaction is: N2(g) + O2(g) ⇌ 2NO(g. If the volume of the container holding the equilibrium mixture is increased from 0.5 L to 1.0 L without changing the quantities of the gas present, how will their concentrations change?

• The concentration of NO will decrease; the concentrations of the reactant gases will increase.

• The concentrations of all the gases will increase.

• The concentrations of the reactant gases will decrease; the concentration of NO will increase.

• The concentration of all the gases will decrease.

Consider the following equilibrium: 2H₂(g) + Y₂(g) ⇌ 2HY(g) + energy. Decreasing the pressure by increasing the volume will cause:

• The reaction to shift right and produce more H₂(g).

• The reaction will shift left to produce more H₂Y(g).

• The reaction will shift right to produce more H₂(g) and Y₂(g).

• The reaction will shift left to produce more H₂(g) and Y₂(g).

Consider the following reaction: 2H₂(g) + X₂(g) ⇌ 2HX(g) + energy. Increasing the temperature will cause a(n):

• Increase in [H₂] and Kₑq will increase.

• Increase in [HX] and Kₑq will decrease.

• Decrease in [HX] and Kₑq will decrease.

• Decrease in [HX] and Kₑq will increase.

Which of the following statements about equilibrium systems is not correct?

• An equilibrium system that is stressed will shift to counteract the stress.

• All equilibrium systems are dynamic.

• The Kₑq value will increase with increasing temperature in an exothermic reaction.

• A reaction achieving minimum enthalpy and minimum entropy will reach equilibrium.

Initially, 1.5 moles of N₂(g) and 3.0 moles of H₂(g) are added to a 1.00 L container, and the following equilibrium reaction was observed: 3H₂(g) + N₂(g) ⇌ 2NH₃(g). If the equilibrium concentration of [NH₃] of 0.68 M at 700 K, what is the Kₑq value for the formation of NH₃(g)?

• 19.5

• 5.13x10⁻²

• 7.55x10⁻²

• 0.21x10⁻¹

Consider the following reaction at equilibrium in a sealed container: PCl₅(g) + Cl₂(g) ⇌ PCl₃(g) ΔH = -89 kJ. Which of the following is false?

• Addition of Cl₂(g) to the container will shift the equilibrium towards the formation of more PCl₅(g)

• A decrease in temperature will shift the equilibrium towards the product side.

• An increase in volume of the container will shift the equilibrium toward the formation of more PCl₅(g)

• Removal of some PCl₅(g) will shift the equilibrium towards the product side.

Consider the reaction: ( 2A_(g) + B_(g) rightleftharpoons C_(g) ). Initially 2.0 moles of A, and 3.0 moles of B are placed into a 5.0 L container. The value of K_eq is 1.4. If 2.0 moles of A and 3.0 moles of B had instead been placed into a 2.5 L container at the same temperature, the K_eq would be:

• 2.8

• 0.7

• 1.4

• 2.0

Equilibrium implies:

• A tendency towards maximum enthalpy.

• A balance between the tendencies towards minimum enthalpy and maximum entropy.

• A tendency toward minimum entropy.

• A balance between the tendencies toward minimum enthalpy and maximum entropy.