Question

Calculate the total pressure in a 10 L cylinder which contains 0.4 g of helium, 1.6 g of oxygen and 1.4 g of nitrogen at 27°C. Also calculate the partial pressure of helium gas in the cylinder. Assume ideal behaviour for gases. 

Answer 1

Moles of He = w/M = 0.4/4 = 0.10

Moles of O = w/M = 1.6/32 = 0.05 2

Moles of N = w/M = 1.4/28 = 0.05 2

Total moles = 0.2 PV = nRT

P x 10 =  0.2 x 0.082 x 300

P = 0.492 atm