What would be most helpful to find the normal melting point and normal boiling point on a phase diagram?

1 Answer
Aug 31, 2016


A ruler?


On a phase diagram, pressure (the #y# axis) is plotted against temperature (the #x# axis). The pressure scale has units of #"atmospheres"# typically, and the temperature scale naturally has units of #"degrees Kelvin"#. Under conditions of low pressure and high temperature, the substance exists as a gas, and at low temperature and high pressure, the substance exists as a solid.

Now the normal melting and the normal boiling points, by definition are the temperatures at which the solid changes to liquid, and the liquid changes to gas at #"ONE ATMOSPHERE"#. So simply draw a horizontal line on the #y# axis, and note the #x# intercepts of the transitions to give these properties.