For a reaction $A + B \rightarrow$ products,$\Delta H = -84.2 \ kJ$ and $\Delta S = -200 \ J \ K^{-1}$. Calculate the highest value of temperature (in $K$) so that the reaction will proceed in the forward direction.

If $\Delta H > 0$ and $\Delta S > 0$,the reaction can proceed spontaneously at:

$A$ reaction,$A + B \rightarrow C + D + q$,is found to have a positive entropy change. The reaction will be:

$\Delta G$ is net energy available to do useful work and is thus a measure of "free energy". Show mathematically that $\Delta G$ is a measure of free energy. Find the unit of $\Delta G$. If a reaction has positive enthalpy change and positive entropy change,under what condition will the reaction be spontaneous?

Which of the following reactions is expected to never be spontaneous?

For a given reaction,$\Delta H = 35.5 \ kJ \ mol^{-1}$ and $\Delta S = 83.6 \ J \ K^{-1} \ mol^{-1}$. The reaction is spontaneous at (Assume that $\Delta H$ and $\Delta S$ do not vary with temperature.)