The heating curve and the phase diagram can be related if you view the heating curve as the change in temperature observed with increased heating at constant pressure. Constant pressure would be a horizontal line on the phase diagram
Segment A on the heating curve diagram represents the solid state, the tan colored region in the phase diagram. All of Segment B happens in the melting point segment of the phase diagram. Temperature does not change until all the sample has melted. In the heating curve, melting point is a horizontal line, in the phase diagram, it is a point on the melting point curve. The oblique line C of the liquid state in the oblique line is the lilac region in the phase diagram. The boiling point segment D on the heating curve is the point on the boiling point curve which separates the liquid region from the gas region in the phase diagram. For water, that would be at 100 °C at 1 atmosphere of pressure. The oblique line E in the heating curve diagram, is the extension of the horizontal line of a pressure of 1 am into the gas region
The phase diagram is useful because it can help you identity the state of matter of a substance or mixture at different conditions of temperature and
pressure.
At the indicated triple point,
• the gas, liquid, and solid state exist in perfect dynamic equilibrium
O only the solid state exists under those conditions
• two of the three states of matter coexist under those conditions.
• there are three different melting points for water.
- The phase diagram can also show the relationship between the different states of matter and the pressure and temperature at which they exist. This can be helpful in understanding how a substance will behave under different conditions.
- The phase diagram can also show the critical point, which is the point at which the liquid and gas phases of a substance become indistinguishable. This is important because it represents the highest temperature and pressure at which the substance can exist as a liquid.
- Overall, the phase diagram provides a visual representation of how a substance will behave at different temperatures and pressures, making it a useful tool in the study of thermodynamics and phase transitions.