Define enthalpy of combustion. Give an example.

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

$2{\mathrm{H}}_{2\left(\mathrm{g}\right)}+{\mathrm{O}}_{2\left(\mathrm{g}\right)}\to 2{\mathrm{H}}_2{\mathrm{O}}_{\left(\mathrm{g}\right)}$

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

${\mathrm{CaCO}}_{3\left(\mathrm{g}\right)}\to {\mathrm{CaO}}_{\left(\mathrm{s}\right)}+{\mathrm{CO}}_{2\left(\mathrm{g}\right)}$

How does the free energy change show the feasibility of a chemical reaction ?

Calculate the entropy of vaporisation for a liquid boiling at $300 \mathrm{K}$ having enthalpy of vaporisation $27 \mathrm{kJ} {\mathrm{mole}}^{-1}$.

Define enthalpy. What is the $\mathrm{SI}$ Unit of enthalpy.