8.4-8.7 Review

Given the equation representing a reaction at equilibrium:

H₂(g) + I₂(g) + heat ↔2HI(g)

Which change favors the reverse reaction?

• increasing the pressure

• decreasing the concentration of HI(g)

• decreasing the temperature

• increasing the concentration of H₂(g)

Fruit growers in Florida protect oranges when the temperature is near freezing by spraying water on them. It

is the freezing of the water that protects the oranges from frost damage. When H₂O(l) at 0°C changes to H₂O (s)

at 0°C, heat energy is released. This energy helps to prevent the temperature inside the orange from dropping

below freezing, which could damage the fruit. After harvesting, oranges can be exposed to ethene gas, C₂H₄, to

improve their color.

Explain, in terms of particle arrangement, why the entropy of the water decreases when the water freezes.

Methanol can be manufactured by a reaction that is reversible. In the reaction, carbon monoxide gas and hydrogen gas react using a catalyst. The equation below represents this system at equilibrium.

CO(g) + 2H₂(g) ↔ CH₃OH(g) + energy

Explain, in terms of collision theory, why increasing the concentration of H₂(g) in this system will increase the concentration of CH₃OH(g).

What information on the graph indicates that the system was initially at equilibrium?

Explain, using LeChatelier's principle, why increasing the concentration of NH₃ at t₂ increases the concentration of H₂.

Common household bleach is an aqueous solution containing hypochlorite ions. A closed container of bleach is an equilibrium system represented by the equation below.

Cl₂(g) + 2OH^-(aq) ↔ ClO^-(aq) + Cl^-(aq) + H₂O(l)

Explain why the container must be closed to maintain equilibrium.

Common household bleach is an aqueous solution containing hypochlorite ions. A closed container of bleach is an equilibrium system represented by the equation below.

Cl₂(g) + 2OH^-(aq) ↔ ClO^-(aq) + Cl^-(aq) + H₂O(l)

Compare the rate of the forward reaction to the rate of the reverse reaction for this system.

Given the system at equilibrium:

H₂(g) + F₂(g) ↔ 2 HF(g) + heat

Which change will not shift the point of equilibrium?

• changing the concentration of HF(g)

• changing the temperature

• changing the pressure

Given the reaction

AgI(s) ↔ Ag⁺(aq) + I^-(aq)

Solution equilibrium is reached in the system when

• dissolving occurs at the same rate that crystallization occurs

• both dissolving and crystallization stops occurring

• crystallization stops occuring

• dissolving stops occuring

Given the reaction at equilibrium:

BaCrO₄(s) ↔ Ba²⁺(aq) + CrO₄^2-(aq)

Which substance, when added to the mixture will cause an increase in the amount of BaCrO₄(s)?