Question

part a.) A mixture of neon and xenon gases is maintained in a 9.44 L flask at a pressure of 3.71 atm and a temperature of 39 °C. If the gas mixture contains 10.5 grams of neon, the number of grams of xenon in the mixture is_____ g.

part b.) The stopcock connecting a 3.94 L bulb containing hydrogen gas at a pressure of 8.05 atm, and a 4.18 L bulb containing neon gas at a pressure of 1.61 atm, is opened and the gases are allowed to mix. Assuming that the temperature remains constant, the final pressure in the system is ______ atm.

Answer 1

PV= nRT

Let us find the moles of neon and xenon mixture

P = 3.71 atm V = 9.44 Liter

n = ? R = 0.0821 L atm K-1 Mol-1

T = 273 + 39 = 312 K

n = 3.71 x 9.44 / 0.0821 x 312 = 1.376 Moles

Moles of neon =  10.5 / 20.17 = 0.4955 Moles

Moles of Xenon = 1.376 - 0.4955 = 0.871 Moles

Mass of Xenon = 0.871 x 131.293 = 114.45 gm

Part B

Let us calculate the moles of gas

n = 8.05 x 3.94 / 0.0821 x 273 = 1.415 Moles

Let us calculate the moles of Neon gas

4.18 x 1.61 / 0.0821 x 273 = 0.3002 Moles

Volume is additive when it is opened

V = 3.94 + 4.18 = 8.12 Liter

Moles of gas also additive

Moles of gas =   1.415 + 0.3002 = 1.715 Moles

Final Pressure in the system = 1.715 x 0.0821 x 273 / 8.12 = 4.734 atm