What is the total pressure in atmospheres of a gas mixture that contains 1.2 g of H2 and 7.5 g of Ar in a 3.8 L container at 27°C? What are?

Molar mass of H₂ = 1.008 × 2 g/mol = 2.016 g/mol
Molar mass of Ar = 39.95 g/mol

Gas law : PV = nRT
Then, P = nRT/V

Partial pressure of H₂ = (1.2/2.016 mol) × [0.08206 atm L / (mol K)] × [(273 + 27) °C] / 3.8 atm = 3.86 atm

Partial pressure of Ar = (7.5/39.95 mol) × [0.08206 atm L / (mol K)] × [(273 + 27) °C] / 3.8 atm = 1.22 atm

Total pressure, P = (3.86 + 1.22) atm = 5.08 atm

1] convert masses to moles
2] Use P = nRT/V to find the partial pressure of each
3] add the partial pressures