Chapter 13, Problem 31E

At 298 K, for the reaction $2{\text{PCl}}_2\left(\text{g}\right)+{\text{O}}_2\left(g\right)\to 2{\text{POCl}}_2\left(\text{l}\right),{\Delta }_{\text{t}}\text{H}°=-620.2\text{kJ}{\text{mol}}^{-1}$ and the standard molar entropies, in ${\text{Jmol}}^{-1}{K}^{-1}$ , are ${\text{PCl}}_{\text{2}}\left(\text{g}\right)$ , 311.8; ${\text{O}}_2\left(g\right)$ , 205.1; and 222.4. Determine (a) ${\Delta }_t\text{G}°$ at 298 K and (b) whether the reaction proceeds spontaneously in the forward or the reverse direction when reactants and products are in their standard states.