Question

1. A mixture of neon, argon and krypton gas has a total pressure of 5.000atm. The mixture is 40.00% argon and 25.00% krypton by volume. What is the partial pressure of neon in the mixture

2. 1.000 mol of xenon gas requires 480.0 s to effuse from a container at 50.0 celcius. How long would it take 1.000 mole of phosphine (PH3) gas to effuse from the same container under identical conditions?

3.A sample of gas has a mass of 2.266g and occupies 824mL at 1.05 atmospheres and 298K. What is the molar mass of the gas?

Answer 1

1.)

mole fraction of Ar = 0.4

mole fraction of Kr = 0.25

mole frction of Ne = 0.35

partial pressure = mole fraction x total pressure

   Ar partial pressure = 0. 4 x 5 = 2 atm

Kr partial pressure = 0.25 x 5 = 1.25 atm

Ne partial pressure = 0.35 x 5 = 1.75 atm

2.)

effusion rate = moles / time

moles same for both gases

effusion = sqrt (1 / molar mass)

t2 / t1 = sqrt (M2 /M1)

t2 / 480 = sqrt (34 /131.29)

t2 = 244 sec

time taken for PH3 = 244 sec

3.)

P V = n R T

P V = w R T / M

M = w R T / P V

M = 2.266 x 0.0821 x 298 / 1.05 x 0.824

M = 64.08 g/ mol

molar mass = 64.08 g/ mol