Question

Calculate the entropy change, for the vaporization of ethyl alcohol, C2H5OH at its boiling point 78.3 ˚C
(heat of vaporization of ethyl alcohol is 39.3 Kj/mol)

Answer 1

Since vaporization at boiling point is an equilibrium process, the entropy change $\Delta S$ can be calculated by equation

$\Delta S=\Delta H/T$

where $\Delta H$ is heat of vaporization and T is boiling temperature in Kelvins.

Thus, the entropy change is

$\Delta S=39300/(78.3+273.15)=$ 111.82 J/(K*mole)