Chapter 4, Problem 4.29UKC

What phase change is shown in the accompanying molecular art? Is energy absorbed or released during the process?

Interpretation Introduction

Interpretation:

The phase change accompanying the molecular art and the process of reaction (exothermic and endothermic) has to be given.

The given diagram is,

Figure 1

Concept introduction:

Endothermic Reactions:

The endothermic process is a term that describes a reaction where the system absorbs the energy from its surrounding in the form of heat.  Few examples of endothermic process is photosynthesis, evaporating liquids, melting ice.

Exothermic reaction:

The exothermic reaction is the opposite of an endothermic reaction.  It releases energy by light or heat to its surrounding.  Few examples are neutralization, burning a substance, reactions of fuels, deposition of dry ice, respiration.

Vaporization:

Vaporization means conversion of a substance from the liquid phase to the gaseous phase.

Explanation of Solution

The given diagram is,

Figure 1

The change in phase can be identified by the distance between the spheres and the level of organization.  A solid has closely packed spheres that are well organized, a liquid has closely packed but randomly arranged spheres, and a gas has randomly arranged spheres that are farther away from each other.

The diagram 1 represents a liquid and the diagram two represents a gas.  Vaporization is the process of change from liquid to gas.  Thus., the phase change accompanied in the figure 1 is a vaporization process and it is an endothermic process because liquid molecules absorb energy to go from liquid state to gaseous state.