For the reaction $C_{(graphite)} + CO_{2(g)} \rightarrow 2CO_{(g)}$,$\Delta H = 170 \ kJ$ and $\Delta S = 170 \ J/K$. At what temperature $(K)$ will the reaction become spontaneous?

Calculate $\Delta H_f^o$ for $UBr_4$ from the $\Delta G^o$ of reaction and the $S^o$ values: $U_{(s)} + 2Br_2(\ell) \to UBr_{4(s)}$; $\Delta G^o = -788.6 \ kJ$; $S^o \ (J/K \cdot mol): U_{(s)} = 50.3, Br_2(\ell) = 152.3, UBr_{4(s)} = 242.6$.

At $273 \ K$ the maximum work done when pressure on $10 \ g$ of hydrogen is reduced from $10 \ atm$ to $1 \ atm$ under isothermal,reversible conditions is (Assume the gas behaves ideally) $(R=8.3 \ J \ K^{-1} \ mol^{-1})$

For the conversion of limestone to lime,$CaCO_{3(s)} \rightarrow CaO_{(s)} + CO_{2(g)}$,the values of $\Delta H^{\circ}$ and $\Delta S^{\circ}$ at $298 \, K$ and $1 \, bar$ pressure are $+179.1 \, kJ \, mol^{-1}$ and $160.2 \, J \, K^{-1} \, mol^{-1}$ respectively. Assuming $\Delta H^{\circ}$ and $\Delta S^{\circ}$ do not change with temperature,at what temperature (in $K$) will the conversion of limestone to lime become spontaneous (in $, K$)?

For a chemical reaction,if $\Delta H > 0$ and $\Delta S > 0$,under what condition will the reaction not be spontaneous?

Calculate the work done in the following reaction at $27^{\circ} C$.
$4 SO_{2(g)} + 2 O_{2(g)} \rightarrow 4 SO_{3(g)}$
$(R = 8.314 \ J \ K^{-1} \ mol^{-1})$ (in $J$)