Holt Ch 18

Multiple Choice

Why is it important to understand reversible reactions and equilibrium in everyday life?

• Because they help explain many natural and industrial processes

• Because they are only found in laboratory settings

• Because they are not relevant to real-world situations

• Because they only occur in biological systems

Open Ended

Describe what is meant by the phrase 'the equilibrium lies to the right' in the context of chemical reactions.

Multiple Select

Which of the following statements about chemical equilibrium are correct?

• The concentrations of products and reactants remain constant at equilibrium.

• Both forward and reverse reactions stop at equilibrium.

• Dynamic equilibrium means both reactions continue with no net change in composition.

• Equilibrium can only be achieved if no substances escape from the system.

Open Ended

List two everyday processes that can easily be reversed and two that cannot.

Multiple Choice

Which of the following best describes a reversible reaction?

• A reaction that only proceeds in one direction

• A reaction where products can react to form reactants

• A reaction that stops once products are formed

• A reaction that cannot reach equilibrium

Fill in the Blanks

A chemical reaction is in

when the rate of its forward reaction equals the rate of its reverse reaction and the concentrations of its products and reactants remain unchanged.

Open Ended

Explain the concept of dynamic equilibrium in a reversible chemical reaction.

Multiple Choice

What is the significance of using double arrows in a chemical equation, as shown in the reaction 2HgO(s) ⇌ 2Hg(l) + O₂(g)?

• It indicates the reaction is irreversible.

• It shows the reaction is at equilibrium and reversible.

• It means the reaction only proceeds forward.

• It represents a decomposition reaction only.

Multiple Choice

When the products of the reverse reaction are favored in a chemical equilibrium, what can be said about the concentrations of reactants and products?

• There is a higher concentration of reactants than products.

• There is a higher concentration of products than reactants.

• The concentrations of reactants and products are equal.

• The reaction stops completely.

Multiple Choice

For the reaction 2SO₂(g) + O₂(g) ⇌ 2SO₃(g), if the products of the forward reaction are favored, the equilibrium lies to the:

• right

• left

• center

• nowhere

Open Ended

Explain how the rates of the forward and reverse reactions change as a chemical system approaches equilibrium.

Multiple Choice

Which of the following statements is true regarding the equilibrium constant (K)?

• A small value of K means the products are favored.

• A large value of K means the reactants are favored.

• Only concentrations of substances that can change are included in K.

• Pure solids and liquids are included in K.

Multiple Select

Which of the following are omitted from the equilibrium expression for a reaction?

• Pure solids

• Pure liquids

• Aqueous solutions

• Gases

Open Ended

Explain the steps required to determine the equilibrium constant (K) for a chemical reaction at equilibrium.

Multiple Choice

If the equilibrium constant K for a reaction is equal to 1, what does this indicate about the concentrations of reactants and products at equilibrium?

• They are roughly equal.

• Reactants are much greater than products.

• Products are much greater than reactants.

• No reaction occurs.

Fill in the Blanks

The equilibrium constant, K, is sometimes referred to as the chemical

expression.

Multiple Choice

For the reaction N2(g) + 3H2(g) ⇌ 2NH3(g), what is the correct equilibrium expression?

• [NH3]2 / ([N2][H2]3)

• [N2][H2]3 / [NH3]2

• [NH3] / ([N2][H2])

• [N2][H2] / [NH3]

Open Ended

Describe how the color change in the H2, I2, HI equilibrium system indicates that equilibrium has been reached.

Multiple Choice

At equilibrium, how do the rates of the forward and reverse reactions compare for the reaction H2(g) + I2(g) ⇌ 2HI(g)?

• The forward rate is greater than the reverse rate.

• The reverse rate is greater than the forward rate.

• The forward and reverse rates are equal.

• Both rates are zero.

Fill in the Blanks

Write the equilibrium constant expression for the reaction: H2(g) + I2(g) ⇌ 2HI(g).

Multiple Choice

Based on the data provided at 425°C, what is the average equilibrium constant (K) for the reaction system involving H2, I2, and HI?

• 54.34

• 53.97

• 54.62

• 54.46

Open Ended

Explain how the equilibrium constant expression can be used to calculate the concentrations of reactants or products at equilibrium.

Open Ended

An equilibrium mixture of N2, O2, and NO gases at 1500 K is determined to consist of 6.4 × 10⁻³ mol/L of N2, 1.7 × 10⁻³ mol/L of O2, and 1.1 × 10⁻⁵ mol/L of NO. What is the equilibrium constant for the system at this temperature?

Multiple Choice

For the reaction N2(g) + O2(g) ⇌ 2NO(g), which of the following is the correct equilibrium constant expression?

• K = [NO]^2 / ([N2][O2])

• K = [N2][O2] / [NO]^2

• K = [NO] / ([N2][O2])

• K = [N2][O2] / [NO]

Multiple Choice

What is one key difference between reversible and irreversible processes in everyday life?

• Reversible processes can go in both directions, while irreversible processes cannot be undone.

• Reversible processes require heat, while irreversible processes do not.

• Irreversible processes always involve a chemical change, while reversible processes do not.

• Reversible processes are always physical changes, while irreversible processes are always chemical changes.