Question 1

which of these quantities determines the amount of heat released when freezing a given amount of a substance?

specific heat capacity

thermal energy

latent heat of fusion

latent heat of vaporization

question 2

the enthalpy of freezing for water is −6.02 kj/mol. what does this indicate?

no heat transfer occurs.

heat is absorbed.

heat is released.

the process is endothermic.

question 3

what does a positive value for enthalpy of vaporization indicate?

the process is endothermic.

the process is exothermic.

no heat transfer occurs.

heat is released by the liquid.

The answers are:

1) Latent heat of fusion

2) Heat is released

3) The process is endothermic

Explanation:

(1) The amount of energy required to freeze one kg of a substance is called latent heat of fusion.

(2) In a process, if heat is absorbed, the change in enthalpy for the substance is positive.

In a process, if heat is released, the change in enthalpy for the substance is negative.

The enthalpy of freezing for water is -6.02 kJ/mol. Heat is released as the enthalpy is negative.

(3) A positive value for enthalpy of vaporization indicates that the process is endothermic.

An exothermic process is one in which energy is released. The enthalpy for the process is negative.

An endothermic process is one which energy is absorbed. The enthalpy for the process is positive.