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 cools until its temperature matches the surroundings. What property of equilibrium does this illustrate?

Accepted Answer

Sameness and constancy

Question 3

Living organisms maintain a body temperature different from their surroundings. This is an example of:

Accepted Answer

Controlled disequilibrium

Question 4

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

Accepted Answer

Molecules must collide with sufficient energy to overcome the activation energy barrier.

Question 5

Which factor increases the rate of a chemical reaction by increasing the number of high-energy collisions?

Accepted Answer

Increasing concentration of reactants

Question 6

For the reaction $$\mathrm{H_2$(g) + I_2$(g) \rightleftharpoons 2HI(g)}$$, which is the correct equilibrium expression?

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?

Accepted Answer

The forward reaction proceeds virtually to completion.

Question 8

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

Accepted Answer

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

Question 10

For the equilibrium $$N_2O_4(g) \rightleftharpoons 2NO_2(g)$$, what happens if $$NO_2 is $$added to the system?

Accepted Answer

The reaction shifts left, producing more N_2O_4.

Question 11

If the volume of a container holding the equilibrium $$N_2(g) + 3H_2(g$$) \rightleftharpoons 2NH_3(g)$$ is decreased, what is the effect?

Accepted Answer

The reaction shifts right, toward fewer moles of gas.

Question 12

Which equation represents the solubility-product constant ($$K_{sp}) $$for barium sulfate?

Accepted Answer

$$K_{sp} = [Ba$$^{2+}$$][SO_4$^{2-}]$$

Question 13

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

Accepted Answer

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

Question 14

Which statement about catalysts is correct?

Accepted Answer

A catalyst lowers the activation energy and speeds up the reaction.

Question 15

In an exothermic reaction, what is the effect of increasing temperature?

Accepted Answer

The reaction shifts left, producing more reactant.

Question 16

For the equilibrium $$Hb + O_2$ \rightleftharpoons $$HbO_2$$, what happens as blood flows through muscles where $$[$$O_2$$]$$ is low?

Accepted Answer

The equilibrium shifts left, unloading oxygen from hemoglobin.

Question 17

Which of the following best explains why hard water leaves deposits on cookware?

Accepted Answer

The solubility-product constants ($$K_{sp}) of $$CaCO$$_3$$ and MgCO$$_3$$ are low, so they precipitate easily.

Question 18

Which statement about enzymes is correct?

Accepted Answer

Enzymes are biological catalysts that lower activation energy and increase reaction rates.

Chapter 15: Chemical Equilibrium – Study Guide

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