Question

Three gases (8.00 g of methane, CH4, 18.0 g of ethane, C2H6, and an unknown amount of propane, C3H8) were added to the same 10.0-L container. At 23.0 ∘C, the total pressure in the container is 4.90 atm . Calculate the partial pressure of each gas in the container.
Express the pressure values numerically in atmospheres, separated by commas. Enter the partial pressure of methane first, then ethane, then propane.

Answer 1

first calculate the total moles

PV = nRT

n = PV/ RT

n = 4.90 x 10.0 / 0.0821 x296 = 49 / 24.3016

n = 2.02

total moles = 2.02

now calculate the moles of methane , ethane

n_CH4  = 8 / 16 = 0.5

n_C2H6   = 18 / 30 = 0.6

now calculate the mole fraction of each gas

X_CH3   = 0.5 / 2.02 = 0.247

X_C2H6   = 0.6 / 2.02 = 0.297

X_C3H8   = 1.0 - 0.247 - 0.297 =0.456

now calculate the partial pressures

P_CH3   = X_CH3 x total pressure

P_CH3 = 0.247 x 4.90

P_CH3 = 1.21 atm

P_C2H6   = 0.297 x 4.90

P_C2H6   = 1.45 atm

P_C3H8   = 0.456 x 4.90

P_C3H8   = 2.23 atm