Question 1

Which statement best describes dynamic equilibrium in a chemical reaction?

Accepted Answer

The rate of the forward reaction equals the rate of the reverse reaction, and concentrations no longer change.

Question 2

A cup of hot water is left undisturbed in a room. What happens as it approaches equilibrium with its surroundings?

Accepted Answer

The water temperature decreases until it matches the room temperature and then remains constant.

Question 3

Which of the following is a defining characteristic of living things with respect to equilibrium?

Accepted Answer

Living things maintain controlled disequilibrium with their environment.

Question 4

According to collision theory, what must occur for a chemical reaction to proceed?

Accepted Answer

Reactant molecules must collide with sufficient energy to overcome the activation energy barrier.

Question 5

Which factor does NOT generally increase the rate of a chemical reaction?

Accepted Answer

Decreasing the concentration of reactants.

Question 6

For the reaction $$\mathrm{H_2$(g) + I_2$(g) \rightleftharpoons 2HI(g)}$$, which expression represents the equilibrium constant $$K_{eq}$$?

Accepted Answer

$$K_{eq} = \frac{[HI]^2}{[H_2$][I_2$]}$$

Question 7

If $$K_{eq}$$ for a reaction is much greater than 1, what does this indicate about the equilibrium mixture?

Accepted Answer

There will be a high concentration of products and a low concentration of reactants.

Question 8

For the reaction $$2N_2O_5(g) \rightleftharpoons 4NO_2(g) + O_2$(g)$$, what is the correct equilibrium expression?

Accepted Answer

$$K_{eq} = \frac{[NO_2$]^4[O_2$]}{[N_2O_5]^2}$$

Question 9

A reaction mixture at equilibrium is disturbed by adding more product. According to Le Châtelier’s principle, what will happen?

Accepted Answer

The reaction will shift to the left, consuming product and forming more reactant.

Question 10

For the equilibrium $$N_2(g) + 3H_2(g$$) \rightleftharpoons 2NH_3(g)$$, what happens if the volume of the container is decreased?

Accepted Answer

The reaction shifts right, toward fewer moles of gas.

Question 11

Which scenario best illustrates the effect of temperature on an exothermic reaction at equilibrium?

Accepted Answer

Increasing temperature causes the reaction to shift left, producing more reactant.

Question 12

Which statement about the solubility-product constant ($$K_{sp}) is $$correct?

Accepted Answer

$$K_{sp} is $$used to describe the solubility of ionic compounds in water.

Question 13

Calculate the molar solubility ($$S) of $$BaSO$$_4$$ given $$K_{sp} = 1.07 	imes 10$$^{-10}$$. Which equation is correct?

Accepted Answer

$$S = \sqrt{K_{sp}}$$

Question 14

Which of the following best describes the effect of a catalyst on a chemical reaction?

Accepted Answer

A catalyst lowers the activation energy, speeding up the reaction without changing the equilibrium position.

Question 15

In the context of health, why does fetal hemoglobin (HbF) load oxygen at a lower concentration than adult hemoglobin?

Accepted Answer

HbF has a larger equilibrium constant than adult hemoglobin.

Question 16

Which of the following is true about the effect of temperature on an endothermic reaction at equilibrium?

Accepted Answer

Increasing temperature causes the reaction to shift right, toward products.

Question 17

A reaction has a high activation energy barrier. Which method will NOT increase the reaction rate?

Accepted Answer

Decreasing the concentration of reactants.

Question 18

Which equation correctly relates the equilibrium constant $$K_{eq} to $$the concentrations for the reaction $$COF_2$$ \rightleftharpoons $$CO_2$$ + $$CF_4$$?

Accepted Answer

$$K_{eq} = \frac{[CO_2$][CF_4$]}{[$$COF_2$$]^2}$$

Question 19

Which real-world scenario is an example of Le Châtelier’s principle in action?

Accepted Answer

Adding population to Middle Earth causes population to flow out of Middle Earth and into Narnia.

Chemical Equilibrium: Principles, Calculations, and Applications

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