1. PROBLEM: What is the total pressure in atmospheres of a gas mixture that contains 1.0 g H2 and 8.0 g of Ar in a 3.0-L container at 27°C? What are the partial pressures of the two gases?
Step 1: Convert g into moles for each gas
1.0 g H2 x 1 mol / 2.02 g = mol H2
8.0 g Ar x 1 mol / g = mol Ar
Step 2: Use PV = nRT to solve for pressure of each gas
PV = nRT – – > PH2 = nRT/V – – > PH2 = mol( atm•L•mol–1•L–1) 300.K
3.0 L
PH2 = – – > 4.1 atm (sig. digits)
PV = nRT – – > PAr = nRT/V – – > PAr = mol( atm•L•mol–1•L–1) 300.K
PAr = – – > 1.6 atm (sig. digits)
Step 3: Add the two partial pressures together to get the total pressure
4.1 atm atm = 5.7 atm