Equilibrium and Reaction Dynamics

Larissa introduces equilibrium, explaining it as a dynamic state where forward and backward reactions occur at equal rates. She discusses the equilibrium constant (KC) and how it indicates the position of equilibrium. The reaction quotient (QC) is introduced as a measure of the ratio of products to reactants at any point. Le Chatelier's principle is explained, showing how systems respond to changes in pressure, temperature, and catalysts. The Haber process is used as an example to illustrate these concepts, highlighting industrial compromises. The session concludes with a review of exam questions.

What does a large value of the equilibrium constant (KC) indicate about a chemical reaction?

• The reaction has stopped.

• The reaction is at a static phase.

• The reaction favors the reactants.

• The reaction favors the products.

How is the reaction quotient (QC) different from the equilibrium constant (KC)?

• QC is only used for gaseous reactions.

• QC is calculated using equilibrium concentrations.

• QC can be calculated at any point in time during the reaction.

• QC is always equal to KC.

According to Le Chatelier's Principle, what happens when the concentration of a product is decreased in a reaction at equilibrium?

• The system shifts to produce more reactants.

• The system shifts to produce more products.

• The system remains unchanged.

• The system stops reacting.

In the context of Le Chatelier's Principle, what effect does increasing pressure have on a gaseous equilibrium system?

• It has no effect on the equilibrium.

• It favors the side with more gas molecules.

• It favors the side with fewer gas molecules.

• It always favors the reactants.

Why is a compromise made in the industrial production of ammonia using the Haber process?

• To avoid using any catalysts.

• To use the lowest possible temperature.

• To balance between cost and reaction rate.

• To maximize the yield of ammonia regardless of cost.

What is the effect of a catalyst on a reaction at equilibrium?

• It shifts the equilibrium to the left.

• It shifts the equilibrium to the right.

• It increases the rate of reaching equilibrium without changing the position.

• It decreases the rate of the reaction.

In the Haber process, why is a relatively high temperature used despite the forward reaction being exothermic?

• To decrease the cost of production.

• To increase the rate of reaction.

• To favor the backward reaction.

• To avoid using a catalyst.

What happens to the equilibrium constant (KC) when the temperature of an exothermic reaction is increased?

• KC becomes zero.

• KC increases.

• KC decreases.

• KC remains unchanged.

How is the equilibrium constant expression written for a reaction?

• Reactants over products.

• Products over reactants.

• Difference between reactants and products.

• Sum of reactants and products.

What is the main reason for using an average pressure in the industrial Haber process?

• To maximize ammonia yield.

• To reduce equipment costs.

• To avoid using high temperatures.

• To increase the reaction rate.