[Moose100]

Ptotal=pO₂+pSO₃+pSO₂

pSO₂/pSO₃=0.152

pO₂/pSO₂= 0.5

Ptotal= 0.5pSO₂ +pSO₂/0.152 + pSO₂

Is this closer? I feel like everything I try is wrong.

Ptotal=8.08pSO₂

pSO₂=2.73/8.08=0.0338
pSO₃=0.338/0.152=2.22
pO₂= 0.169

k=[pSO₂]²[pO₂]/[pSO₃]²

k=[0.338]²[0.169]/[2.22]²
k=3.9 × 10^-3