Question

Which of the following is likely to be true about the ΔH for this reaction?

C6H6(l) → C6H6(s)

a. H < 0
b. H = 0
c. H > 0

Answer 1

I would say A.

Because it is cooling down, going from liquid to solid, so it is loosing energy. THis energy must be being released to the surroundings so

Answer 2

Answer: Option (a) is the correct answer.

Step-by-step explanation:

Enthalpy is defined as the total amount of heat present in a system.

When there is bond formation in a chemical reaction then it means energy is released. Hence, the reaction is exothermic in nature and
`\Delta H` < 0 or negative.

On the other hand, when breaking of bonds occurs then energy is absorbed by the system. Hence, the reaction is endothermic in nature and
`\Delta H` > 0 or positive.

Thus, in the given reaction
`C_(6)H_(6)(l) \rightarrow C_(6)H_(6)(s)`, the state is changing from liquid to solid.

This means atoms are coming close to each other and hence, there is occurrence of bond formation. As a result, energy will be released to the surroundings.

Hence, we can conclude that H < 0 for the given reaction.