Thu July 26, 2012 By: Nilesh Raikar

A gas cylinder holds 85g of a gas ‘X’ . The same cylinder when filled with hydrogen holds 8.5g of hydrogen under the same conditions of temperature and pressure.calculate the molecular weight of ‘X’.

Expert Reply
Fri July 27, 2012

Since the cylinder has same conditions of temperature and pressure for both the gases X and Hydrogen so, from the ideal gas equation we can infer that,


Where, n1=number of moles of gas X = mass in system/Molecular Mass

                                                     = 85 / Molecular Mass

n2=number of moles of hydrogen = mass in system/Molecular Mass = 8.5 / 2

Molecular Mass = (85 x 2) / 8.5

Molecular Mass of gas X = 20 g/mol


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