Given the balanced equation representing a phase change:

C6H4Cl2(s) + energy==>C6H4Cl2(g)

Which statement describes this change?

(1) It is endothermic, and entropy decreases.

(2) It is endothermic, and entropy increases.

(3) It is exothermic, and entropy decreases.

(4) It is exothermic, and entropy increases.

The answer is (2). The energy is at left of the equation, so it absorbs energy. It is called endothermic. And the entropy is a measure of disorder. The disorder degree of gas is more than solid. So the entropy increases.

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kobenhavn kobenhavn · Answer 2 · 2019-03-16T01:05:54-04:00

Answer: (2) It is endothermic, and entropy increases.

Explanation: Endothermic reactions are those in which heat is absorbed by the system and exothermic reactions are those in which heat is released by the system.

Entropy is the measure of randomness or disorder of a system. If a system moves from an ordered arrangement to a disordered arrangement, the entropy is said to decrease and vice versa.

In the given reaction:

$C_6H_4Cl_2(s)+energy\rightarrow C_6H_4Cl_2(g)$

The energy is absorbed by the reactants and thus it is endothermic and the solid reactants are converting to gaseous products, thus the entropy increases.