Use Dalton\'s Law of partial pressures. P(Total)=P(H2)+P(H20) p(H2)=P(Total)- P(H20) Look up the partial pressure of water at the given temperature. It comes out to be 0.0351 atm. P(H2)=1-0.0351 = 0.9649 atm Solution Use Dalton\'s Law of partial pressures. P(Total)=P(H2)+P(H20) p(H2)=P(Total)- P(H20) Look up the partial pressure of water at the given temperature. It comes out to be 0.0351 atm. P(H2)=1-0.0351 = 0.9649 atm.