Q: For the reaction $$2\text{H}_2(g) + \text{O}_2(g) \rightleftharpoons 2\text{H}_2\text{O}(g)$$, what is the correct expression for the equilibrium constant $$K$$?

$$K = \dfrac{[\text{H}_2\text{O}]^2}{[\text{H}_2]^2 [\text{O}_2]}$$

Question 1

Which of the following best describes a closed system in the context of chemical equilibrium?

Accepted Answer

A system where energy can be exchanged with the surroundings, but matter cannot.

Question 2

Which symbol is used to represent a reversible reaction in a chemical equation?

Accepted Answer

$$\rightleftharpoons$$

Question 3

At dynamic equilibrium, which of the following statements is true?

Accepted Answer

The rates of the forward and reverse reactions are equal.

Question 4

According to Le Chatelier's Principle, what will happen if more reactant is added to a system at equilibrium?

Accepted Answer

The equilibrium will shift to the right to use up the extra reactant.

Question 5

For the reaction $$2	ext{H}_2(g) + 	ext{O}_2(g) ightleftharpoons 2	ext{H}_2	ext{O}(g)$$, what is the correct expression for the equilibrium constant $$K$$?

Accepted Answer

$$K = \dfrac{[	ext{H}_2	ext{O}]^2}{[	ext{H}_2]^2 [	ext{O}_2]}$$

Question 6

If the temperature of an exothermic reaction at equilibrium is increased, what will happen to the position of equilibrium?

Accepted Answer

It will shift to the left, producing more reactants.

Question 7

Which of the following changes will NOT affect the position of equilibrium in a chemical reaction?

Accepted Answer

Adding a catalyst

Question 8

A reaction in a closed container reaches equilibrium. What happens to the concentrations of reactants and products after equilibrium is reached?

Accepted Answer

They remain constant, but not necessarily equal.

Question 9

In the reaction $$	ext{N}_2(g) + 3	ext{H}_2(g) ightleftharpoons 2	ext{NH}_3(g)$$, what will happen if the pressure is increased?

Accepted Answer

The equilibrium will shift to the right, producing more ammonia.

Question 10

Which of the following best explains why equilibrium can only be established in a closed system?

Accepted Answer

Because reactants and products can escape, preventing equilibrium.

Question 11

A chemist wants to maximize the yield of ammonia in the Haber process ($$	ext{N}_2 + 3	ext{H}_2 ightleftharpoons 2	ext{NH}_3). $$Which combination of conditions would be most effective?

Accepted Answer

Low temperature, high pressure

Question 12

Which of the following is true about the effect of a catalyst on a reversible reaction at equilibrium?

Accepted Answer

It speeds up both the forward and reverse reactions equally.

Question 13

If water vapor is removed from the equilibrium mixture $$2	ext{H}_2(g) + 	ext{O}_2(g) ightleftharpoons 2	ext{H}_2	ext{O}(g)$$, what will happen to the position of equilibrium?

Accepted Answer

It will shift to the right to replace the lost water vapor.

Question 14

Which of the following is a correct statement about dynamic equilibrium?

Accepted Answer

The rates of the forward and reverse reactions are equal.

Question 15

A reaction is exothermic in the forward direction. What will happen if the temperature is decreased?

Accepted Answer

The equilibrium will shift to the right, favoring product formation.

Question 16

Which of the following scenarios best illustrates Le Chatelier's Principle?

Accepted Answer

A reaction at equilibrium shifts to produce more products when more reactant is added.

Dynamic Equilibrium and Le Chatelier's Principle: Study Notes for Introductory Chemistry

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