Question

A certain mass of hydrogen gas collected over water at 10°C and 750mmHg pressure has a volume of 57cm3. Calculate the volume when it is dry at S.T.P ( S.V.P of water at 10°C = 9.2 mmHg .​

Answer 1

The volume of gas when it is dry at S.T.P : 53.6 cm³

Further explanation

Given

P tot=750 mmHg

V₁=57 cm³

T₁=10 °C = 283 K

P₂ = 760 mmHg(STP)

T₂ = 273 K(STP)

Required

P dry gas at STP

Solution

Dalton's Law

P tot = P H₂O + P gas

P gas = 750 mmHg - 9.2 mmHg

P gas = 740.8 mmHg = P₁

Combined gas Law

`\tt (P_1.V_1)/(T_1)=(P_2.V_2)/(T_2)\\\\V_2=(P_1.V_1.T_2)/(T_1.P_2)\\\\V_2=(740.8* 57* 273)/(283* 760)=53.6~cm^3`