Question

A 32.6 L glass container has a total pressure of 640 mmHg at 20˚C and contains three different gases, methane (CH,4) helium and CO2.If the partial pressure of CH4 is 280 mmHg and the partial pressure of He is 160 mmHg, what is the mass of CO2 in the container?

Answer 1

1st calculate partial pressure of CO2

p(CO2) = total P - p(CH4) - p(He)

= 640 mmHg - 280 mmHg - 160 mmHg

= 200 mmHg

Given:

P = 200 mm Hg

= (200/760) atm

= 0.2632 atm

V = 32.6 L

T = 20.0 oC

= (20.0+273) K

= 293 K

find number of moles using:

P * V = n*R*T

0.2632 atm * 32.6 L = n * 0.08206 atm.L/mol.K * 293 K

n = 0.3568 mol

Molar mass of CO2,

MM = 1*MM(C) + 2*MM(O)

= 1*12.01 + 2*16.0

= 44.01 g/mol

use:

mass of CO2,

m = number of mol * molar mass

= 0.3568 mol * 44.01 g/mol

= 15.7 g

Answer: 15.7 g