52 The hydrogen gas formed in a chemical reaction is collect

52. The hydrogen gas formed in a chemical reaction is collected over water at 30.0 C at a total pressure of 736 mmHg . Part A What is the partial pressure of the hydrogen gas collected in this way? Part B If the total volume of gas collected is 724 mL , what mass of hydrogen gas is collected?

Solution

A)

Pgas = Ptotal - Pvapor

PVapor(T=30°C) = 31.8 mm Hg

P-gas = 736-31.8 = 704.2 mm Hg

B)

Vtotal = 724 mL

find mass

PV = nRT

n = PV/(RT) = (704.2 *0.724)/(62.4*303) = 0.02696

mass = mol*MW = 0.02696*2 = 0.05392 g of H2