Phase diagrams

A phase diagram is a graphical representation of the equilibrium relationships that exist between the phases of a substance under specified pressures and temperatures (Figure 1.1). The phase diagram is a combination of three curves: the vapour pressure curve, the melting curve and the sublimation curve. We have previously seen that vapour pressure curves represent the equilibrium between the liquid and gas phase, and the point at which the pressure equals 1 atm is the normal boiling point. One additional feature of this curve in the phase diagram (green), is that it ends at the critical point. The critical point is the point at the highest temperature and pressure at which liquids and gases remain distinguishable. At temperatures and pressure beyond this point the matter exists in a phase with properties of both liquids and gases known as a supercritical fluid.

The melting curve (orange) represents the equilibrium between solid and liquid, and the point at which the pressure equals 1 atm is the normal melting point. The sublimation curve (blue) represents the equilibrium which exists between solid and gas. Finally, the point where all three curves meet is known as the triple point. At this point, three phases (solid, liquid and gas) all exist at equilibrium.

Figure 1.1. A generic phase diagram.

Using the following phase diagram, determine what would happen if:

a. The temperature is increased for matter at point 1.

b. The pressure is increased for matter at point 3.

a. Matter at point 1 will melt (change phase from solid to liquid) if the temperature is increased.

b. Matter at point 3 will condense (change phase from gas to liquid) if the temperature is increased.

مواضيع ذات صلة

تطبيقات الامتزاز Applications Of Adsorption

الامتزاز من المحلول ِAdsorption from Solution

أنواع الامتزاز Types of adsorption

البوليمرات الموصلة المالئة Filled Conductive Polymer

البوليمرات الموصلة كهربائياًElectrically Conducting Polymers

المواد فائقة التوصيلية Super Conductors

أشباه الموصلات Semiconductors

المواد العازلة Insulators

الموصلات المعدنية أو الالكترونية Conductors or Metals

التوصيلية والتركيب الالكتروني للمواد الموصل Conductivity and electronic structure of conducting materials

قانون أوم

التوصيلية الكهربائية Electrical Conductivity