Question

why is volume a partial molar quantity but not temperature and pressure​

Answer 1

Answer:

Partial molar volumes help to assess the influence of pressure on phase equilibria or reaction equilibria. The prediction of partial molar volumes or excess volumes is a sharp test for theories of the fluid state.

On the other hand, the interpretation of partial molar volumes or excess volumes is usually difficult, if not impossible. Many mixtures exhibit positive and negative excess volumes, depending on composition, temperature, and pressure. Speculations why some mixture exhibits positive or negative excess volumina are futile, particularly if they are based on measurements at ambient pressure and temperature only.