Question

A mixture of nitrogen and krypton gases is maintained in a 5.73 L flask at a pressure of 1.34 atm and a temperature of 34 °C. If the gas mixture contains 3.73 grams of nitrogen, the number of grams of krypton in the mixture is ____

The stopcock connecting a 3.55 L bulb containing krypton gas at a pressure of 5.21 atm, and a 9.64 L bulb containing helium gas at a pressure of 2.14 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

According to ideal gas equation,

PV = nRT

1.34 * 5.73 = n * 0.0821 * (34+273)

n = number of moles of mixture = 0.3046 moles

number of moles of N2 + number of moles of Kr = 0.3046

3.73/28 + x/40 = 0.3046

x = mass of Kr = 6.8554 g

Assume the temperature of the sysytem = 298 K

number of moles of Kr = PV/RT = 5.21*3.55/(0.0821*298)

number of moles of Kr = 0.756 moles

number of moles of He = PV/RT = 2.14*9.64/(0.0821*298)

number of moles of He = 0.8432 moles

Total Pressure = partial pressure of Kr + partial pressure of He

PT = [n(RT/V)] for Kr + [n(RT/V)] for He

Pt = (0.756*0.0821*298/(3.55+9.64)) + (0.8432*0.0821*298/(3.55+9.64))

Pt = 2.9663 atm