Question

Classify the following phase changes by the signs of the system's delta H and delta S.

 

Answer 1

Liquid to gas:

Heat is added, \(\Delta H=+\mathrm{ve}\)

Randomness increases due to a lack of intermolecular forces between

the molecules, \(\Delta S=+\) ve

Gas to Liquid:

Heat is removed, \(\Delta H=-\) ve

Randomness decreases due to an increase in intermolecular forces between

the molecules, \(\Delta S=-\) ve

Solid to gas:

 

Heat is added, \(\Delta H=+\mathrm{ve}\)

Randomness increases due to a lack of intermolecular forces between

the molecules, \(\Delta S=+\mathrm{ve}\)

Gas to solid:

Heat is removed, \(\Delta H=-\mathrm{ve}\)

Randomness decreases due to an increase in intermolecular forces between

the molecules, \(\Delta S=-\mathrm{ve}\)

Solid to liquid:

Heat is added, \(\Delta H=+\mathrm{ve}\)

Randomness increases due to a lack of intermolecular forces between

the molecules, \(\Delta S=+\mathrm{ve}\)

Liquid to solid:

Heat is removed, \(\Delta H=-\) ve

Randomness s decreases due to an increase in intermolecular forces between

the molecules, \(\Delta S=-\) ve