Question

A balloon has a mass of 0.5g when completely deflated. When it is filled with an unknown gas, the mass increases to 1.7g. You notice that the unknown gas occupies a volume of 0.4478L at a temperature of 50.0 degrees C. You have noted that the initial temperature of the room, and thus the gas, is at 25 degrees C. Identify the gas.

Show your work.

Answer 1

volume of gas can be obtained using Charless law according to which

V1/T1= V2/ T2 ( at constant pressure)

0.4478/(50+273.15)= V2/ (25+273.15) V2 =0.413157 L

From PV= nRT

P =1 atm ( assumed) , T= 298.15 , R = 0.08206 Lit.atm/moleK and V =0.413157 L

n= PV/RT= 1*0.413157/ ( 0.08206*298.15) =0.016687 moles

Mass of the gas = 1.7-.0.5 = 1.2 gms

Mole= mass/ molecular weight and   hence

molecular weight = mass/ mole = 1.2/0.016687 =71.06

The gas is chlorine