For a spontaneous change,free energy change $\Delta G$ is

For a certain reaction, $\Delta H = -50 \text{ kJ}$ and $\Delta S = -100 \text{ J/K}$. Find the temperature range at which the reaction is spontaneous.

Calculate the amount of work done during isothermal expansion of a gas from a volume of $4 \ dm^{3}$ to $6 \ dm^{3}$ against a constant external pressure of $3 \ atm$ (in $J$)?

The reaction $MgO_{(s)} + C_{(s)} \to Mg_{(s)} + CO_{(g)}$,for which $\Delta_r H^o = +491.1 \ kJ \ mol^{-1}$ and $\Delta_r S^o = 198.0 \ J \ K^{-1} \ mol^{-1}$,is not feasible at $298 \ K$. The temperature above which the reaction will be feasible is ..... $K$.

The densities of graphite and diamond at $298 \, K$ are $2.25 \, g \, cm^{-3}$ and $3.31 \, g \, cm^{-3}$ respectively. If the standard free energy difference $(\Delta G^o)$ is $1895 \, J \, mol^{-1}$, the pressure at which graphite will be transformed into diamond at $298 \, K$ is:

Calculate the value of $\Delta G$ for the following reaction at $300 \ K$.
$H_2O_{(s)} \longrightarrow H_2O_{(l)}$
$(\Delta H = 7 \ kJ, \Delta S = 24.8 \ J \ K^{-1})$