Chapter 12, Problem 12.10P

Interpretation Introduction

Interpretation:

The phase changes that are involved when solid vaporizes directly, and the vapor crystallizes on a cool surface is to be determined.

Concept introduction:

The phase is defined as the physical state of a substance. The properties of a phase are determined by the interaction of the potential energy $\left(E_p\right)$ and kinetic energy $\left(E_{\text{k}}\right)$ of particles. There are three major phases as follows:

1) Solid

2) Liquid

3) Gas

Endothermic reactions are the reactions in which energy in the form of the heat or light is absorbed by the reactant for the formation of the product. $\Delta H$ is positive in the endothermic reactions.

Exothermic reactions are the reactions in which energy in the form of the heat or light is released with the product. $\Delta H$ is negative in the exothermic reactions.

Condensing, freezing, and deposition are exothermic processes while melting, vaporizing, and subliming are endothermic processes.