Define heat of fusion.

What is bond energy ?

Predict whether $∆\mathrm{S}$ is $+\mathrm{ve}$ or $-\mathrm{ve}$ for the following reaction:

${\mathrm{N}}_2{{\mathrm{O}}_5}_{\left(\mathrm{g}\right)}\to {\mathrm{N}}_2{\mathrm{O}}_{3\left(\mathrm{g}\right)} + {\mathrm{O}}_{2\left(\mathrm{g}\right)}$.

Predict whether $∆\mathrm{S}$ is $+\mathrm{ve}$ or $-\mathrm{ve}$ for the following reaction:

${{\mathrm{NH}}_3}_{\left(\mathrm{g}\right)}+{\mathrm{HCl}}_{\left(\mathrm{g}\right)}\to {\mathrm{NH}}_4{\mathrm{Cl}}_{\left(\mathrm{s}\right)}$

Which of the following is an intensive property ?

(mass, energy, and temperature)

Write the equation relating free energy,entropy and enthalpy.

What are the components of internal energy ?

State two important conditions which account for the spontaneity of a reaction.