A 5.00-L gas sample at 100.°C and 640. torr contains 20.3% neon and 79.7% xenon by mass. What are the partial pressures of the individual gases?

The answers to the question are

Partial pressure of neon = 399.42

Partial pressure of xenon = 240 torr

Explanation:

From the universal gas equation

P×V = n × R × T

n = P × V÷(R×T)

= ((640 torr /(7.5×10^(-3))× 5/ L)÷(8.314×373.15))/1000

= 0.13751 moles

Therefore, if the mass of gas = x, we have

0.203×x mass of neon and

0.797×x mass of xenon

Molar mass of neon = 20.179 g/mol

Molar mass of xenon = 131.30 g/mol

Summing the moles of neon and xenon, we have

(0.203×x)/ (20.179) + 0.797×x/( 131.30) = 0.13751 moles

1.6×10^(-2)x= 0.13751

x = 8.5306 g

Number of moles of neon =

(0.203× 8.5306 )/ (20.179) = 8.58×10(-2) moles

Mole fraction of neon = (8.58×10(-2))/ 0.13751 = 0.624

Partial pressure of neon = (mole fraction)×(total pressure of gas) = 0.624× 640 torr = 399.42 torr

Partial pressure of xenon = 240 torr

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