Equilibrium and Reaction Dynamics

Dr. English introduces chemical equilibrium and Le Chatelier's principle, focusing on energy changes and their effects on equilibrium. The video covers endothermic and exothermic reactions, practice examples, and the role of catalysts in reaction rates. It concludes with practice questions to reinforce learning.

What happens to a system at equilibrium when energy is added?

• The system shifts to absorb energy.

• The system remains unchanged.

• The system becomes unstable.

• The system shifts to release energy.

In an endothermic reaction, what is the effect of adding heat?

• The reaction shifts to the left.

• The reaction shifts to the right.

• The reaction rate decreases.

• The reaction becomes exothermic.

What is the result of removing heat from an exothermic reaction at equilibrium?

• The reaction rate increases.

• The reaction shifts to the right.

• The reaction becomes endothermic.

• The reaction shifts to the left.

How does the removal of heat affect the equilibrium of a reaction with heat as a product?

• It becomes unstable.

• It remains unchanged.

• It shifts towards products.

• It shifts towards reactants.

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

• It slows down the reaction.

• It speeds up the reaction without changing the equilibrium position.

• It shifts the equilibrium to the left.

• It shifts the equilibrium to the right.

Which of the following is true about a catalyst in a chemical reaction?

• It increases the concentration of products.

• It increases the activation energy.

• It decreases the concentration of reactants.

• It provides an alternative pathway with lower activation energy.

What happens to the concentration of ammonia when the temperature is decreased in a reaction where ammonia is a product?

• The reaction becomes endothermic.

• The concentration of ammonia remains the same.

• The concentration of ammonia decreases.

• The concentration of ammonia increases.

In a reaction at equilibrium, what effect does decreasing the temperature have on an exothermic reaction?

• It shifts the equilibrium towards reactants.

• It has no effect on the equilibrium.

• It shifts the equilibrium towards products.

• It increases the activation energy.

Which change favors the reverse reaction in an equilibrium system?

• Increasing the pressure in a reaction with equal moles of gas on both sides.

• Decreasing the temperature in an exothermic reaction.

• Decreasing the concentration of reactants.

• Increasing the concentration of products.

What occurs when a catalyst is added to a chemical reaction?

• The equilibrium position shifts to the right.

• The reaction pathway changes with lower activation energy.

• The reaction pathway remains the same with higher activation energy.

• The equilibrium position shifts to the left.