# At equilibrium, the partial pressure of SO_2 is 35.0 atm and that of O_2 is 15.9 atm. What is the partial pressure of SO_3 in atm?

$2 S {O}_{2} + {O}_{2} \rightarrow 2 S {O}_{3}$
${K}_{p} = \frac{{p}_{S {O}_{3}}^{2}}{{p}_{S {O}_{2}}^{2} \times {p}_{{O}_{2}}}$ $=$ ??
We need to know ${K}_{p}$ in order to access ${p}_{S {O}_{3}}$.