The standard enthalpies of formation for $\mathrm{S}(g), \mathrm{F}(g),
\mathrm{SF}_{4}(g),\( and \)\mathrm{SF}_{6}(g)\( are \)+278.8,+79.0,-775,$ and
\(-1209 \mathrm{kJ} / \mathrm{mol}\) respectively.
a. Use these data to estimate the energy of an \(\mathrm{S}-\) F bond.
b. Compare your calculated value to the value given in Table \(8.5 .\) What
conclusions can you draw?
c. Why are the \(\Delta H_{f}^{\circ}\) values for \(\mathrm{S}(g)\) and
\(\mathrm{F}(g)\) not equal to zero, since sulfur and fluorine are elements?