Chapter 13.4, Problem 29LC

Interpretation Introduction

Interpretation:

The triple point on a phase diagram is to be described.

Concept Introduction:

A phase diagram is a graphical representation of a substance's physical state under various pressures and temperatures.

Answer to Problem 29LC

The triple point denotes the lowest pressure at which a liquid phase can coexist in equilibrium with a solid or vapor.

Explanation of Solution

Phase diagrams show how variations in the physical states of matter of elements or compounds relate to pressure and temperature. Pressure (usually measured in atmospheres) and temperature are plotted on phase diagrams (typically in degrees Celsius or Kelvin). The stable states of an equilibrium system are represented by the labels on the graph. The curved lines show the ranges of pressures and temperatures where two phases can coexist peacefully. In other words, these lines indicate the locations of phase changes.

The triple point in the phase diagram is the point at which all the three-phases coexist in equilibrium. Thus, the triple point denotes the lowest pressure at which a liquid phase can coexist in equilibrium with a solid or vapor.