Question

How can you tell density from a phase diagram?

Answer 1

Hint: You should know how the phase diagram is drawn for different molecules. The phase diagram shows the change in the phase of the molecule from one state to another. Solid is denser than liquid and liquid is denser than gas.

Complete step by step answer:
Phase diagram is a graphical representation used for showing the physical states of a substance under different conditions of temperature and pressure. In a typical phase diagram pressure is present on the y-axis and the temperature is present on the x-axis.
A phase transition is defined as the transition taking place from one state of matter to the other. There are three states of matter: Solid, liquid and gases.
The phase diagrams show variations between the states of matter of an element in relation with the pressure and the temperature.

The labels given in the graph shows the stable states of the system present in equilibrium. The lines present show the combination of pressure and temperature at which the two phases can exist in equilibrium. These lines represent the change in phase point. The red line divides the solid and gas phases which shows sublimation process (change of phase from solid to gas) and deposition process (change of phase from gas to solid). The green line divides the solid and liquid phases and represents the melting process (change of phase from solid to liquid) and freezing process (change of phase from liquid to solid). The blue divides the liquid and gas phases, represents the vaporization process (change of phase from liquid to gas) and condensation (change of phase from gas to liquid). There are two other points on the diagram, the triple point and the critical point. The triple point shows the combination of pressure and temperature that facilitates all phases of matter at equilibrium. The critical point terminates the liquid/gas phase line and shows relation with the critical pressure, the pressure above which a supercritical fluid is generated.
When we move along the constant temperature line, the relative densities of all the phases can be determined. On moving from the bottom of the diagram to the top, the relative density increases.

Note:
As we move along the constant pressure line, the relative energies of the phases is determined. As we move from left to right in the diagram, the relative energy increases.