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.

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

Which equation correctly represents the equilibrium constant for the reaction $$aA + bB \rightleftharpoons cC + dD$$?

Accepted Answer

$$K_{eq} = \frac{[C]^c [D]^d}{[A]^a [B]^b}$$

Question 4

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

Accepted Answer

The reaction favors the formation of products.

Question 5

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 6

Which factor increases the rate of a chemical reaction according to collision theory?

Accepted Answer

Increasing the concentration of reactants

Question 7

What effect does increasing the temperature have on the rate of a chemical reaction?

Accepted Answer

It increases the number of high-energy collisions.

Question 8

A reaction mixture contains $$[H_2$] = 0.11\,M$$, $$[I_2$] = 0.11\,M$$, and $$[HI] = 0.78\,M. $$What is the equilibrium constant for $$H_2(g$$) + $$I_2(g$$) \rightleftharpoons 2HI(g)$$?

Accepted Answer

$$K_{eq} = \frac{[HI]^2}{[H_2$][I_2$]} = \frac{(0.78)^2$}{(0.11)(0.11)} = 5.0 	imes 10^1$

Question 9

When a system at equilibrium is disturbed by adding more reactant, what happens according to Le Châtelier’s principle?

Accepted Answer

The reaction shifts to the right, forming more products.

Question 10

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

Accepted Answer

The reaction shifts to the right, toward fewer moles of gas.

Question 11

Which statement about the effect of a catalyst on a chemical reaction is correct?

Accepted Answer

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

Question 12

What is the solubility-product constant ($$K_{sp}) $$expression for $$BaSO_4(s$$) \rightleftharpoons $$Ba^{2+}(aq$$) + $$SO_4$$^{2-}(aq)$$?

Accepted Answer

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

Question 13

If $$K_{sp}$$ for $$BaSO_4 is$$ $$1.07 	imes 10$$^{-10}$$, what is its molar solubility (S$)?

Accepted Answer

$$S = \sqrt{K_{sp}} = \sqrt{1.07 	imes 10$$^{-10}$$} = 1.03 	imes 10$$^{-5}$$\,M$$

Question 14

Which scenario best illustrates controlled disequilibrium in living organisms?

Accepted Answer

A living organism maintaining a constant internal temperature different from its surroundings.

Question 15

What happens to the equilibrium position of an exothermic reaction when the temperature is increased?

Accepted Answer

The reaction shifts to the left, forming more reactants.

Question 16

In 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 to the left, unloading oxygen from hemoglobin.

Question 17

Which of the following is true about the effect of volume change on equilibrium for a reaction with equal moles of gas on both sides?

Accepted Answer

A change in volume has no effect on the equilibrium position.

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 – Structured Study Notes

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