Chapter 12.4, Problem 32SSC

Interpretation Introduction

Interpretation:

The significance of triple point and critical point on a phase diagram must be explained.

Concept introduction:

Phase diagram is a graphical representation of the phase change of a substance along with temperature and pressure.

Answer to Problem 32SSC

Triple point is the temperature and pressure at which all the three phases i.e solid, liquid and gas coexist. Critical point is the temperature at which liquid is in equilibrium with gas.

Explanation of Solution

In phase diagram solid, liquid and gas are represented by separate lines. There is a point at which all the lines i.e solid, liquid and gas meet. This is the temperature and pressure at which all the physical states are present at the same time. This is known as triple point of the substance.

For example triple point of water is at 0.01°C and 4.58 mmHg pressure.

Critical point is the condition for which the liquid and gas phase are in equilibrium. Above critical point it is gas which can’t be liquefied easily unlike vapor.

Conclusion

Triple point is the condition in which solid, liquid and gas are in equilibrium.

Critical point is the condition at which liquid is in equilibrium with gas.