Questions

Explanations

21 What occurs when a reaction reaches equilibrium?

(1) The concentration of the reactants increases.

(2) The concentration of the products increases.

(3) The rate of the forward reaction is equal to the rate of the reverse reaction.

(4) The rate of the forward reaction is slower than the rate of the reverse reaction.

22 In terms of potential energy, PE, which expression defines the heat of reaction for a chemical change?

23 Systems in nature tend to undergo changes that result in

(1) lower energy and lower entropy

(2) lower energy and higher entropy

(3) higher energy and lower entropy

(4) higher energy and higher entropy

24 What occurs when Cr³⁺ ions are reduced to Cr²+ions?

(1) Electrons are lost and the oxidation number of chromium increases.

(2) Electrons are lost and the oxidation number of chromium decreases.

(3) Electrons are gained and the oxidation number of chromium increases.

(4) Electrons are gained and the oxidation number of chromium decreases.

25 Where do reduction and oxidation occur in an electrolytic cell?

(1) Both occur at the anode.

(2) Both occur at the cathode.

(3) Reduction occurs at the anode, and oxidation occurs at the cathode.

(4) Reduction occurs at the cathode, and oxidation occurs at the anode.