Chapter 21, Problem 12STP

Interpretation Introduction

Interpretation:

The changes occurs in molecular arrangement which takes place when the pressure is increased from 8 atm to 16 atm and the temperature remains constant at should be described.

Concept introduction:

When energy or heat is gain or lost by any matter, the matter changes its state to form a state of matter.

State of matter is classified as:

1. Solid
2. Liquid
3. Gas

A graphical diagram which represents the physical states of a substance under different values of temperature and pressure is known as phase diagram.

The general representation of phase diagram is:

Triple point of a substance is defined as the point at which solid, liquid and gas phase or state of that substance coexist in the equilibrium.

Answer to Problem 12STP

A substance changesfrom gas phase to liquid phase when the pressure is increased from 8 atm to 16 atm and the temperature remains constant at

Explanation of Solution

The given graph is:

Graph can be redrawn as:

From above graph and general graph of phase diagram, at pressure 8 atm and temperature ofthe labeled area (C) represents gas phase.

When the pressure is increased tochange in state occurs.

Graph can be drawn as:

In above graph, one can see that the when the pressure is 16 atm, then by drawing straight line or parallel line to y-axis, substance crosses the line into liquid state.

Thus, when the pressure is increased from 8 atm to 16 atm and the temperature remains constant atthen a substance changes from gas state to liquid state.