Answer to Question #304095 in General Chemistry for Brandi

Question

Helium gas is contained in a tank with a pressure of 12.4 MPa. If the temperature inside the tank is 32.8 Celsius and the volume of the tank is 18.0 L, determine the mass of the helium in the tank.

Answer 1

Ideal gas law:

pV = nRT

p = 12.4 MPa = 12.4 x 10⁶ Pa = 122.4 atm

T = 32.8°C = 32.8 + 273.15 = 305.95 K

V = 18.0 L

R = 0.08206 L atm mol⁻¹ K⁻¹

n = pV/RT

n = (122.4 atm)(18.0 L)/(0.08206 L atm mol⁻¹ K⁻¹)(305.95 K) = 87.76 mol He

n = m/Mr

m = n x Mr = 87.76 mol x 4 g/mol = 351.04 g