A sample of a liquid hydrocarbon known to consist of

Solution 40P

Here we have to calculate the molecular formula of the hydrocarbon.

Step 1

Given:

Volume = 0.204 L

Temperature = 101 oC = 273 + 101 = 374 K

Pressure = 767 torr = 1.00921 atm

Mass of gas = 0.482 g

In order to find out the molecular formula of the hydrocarbon, we have to calculate its molecular mass by using ideal gas equation as follows,

According to ideal gas equation it is known that it is known that ,

 PV = n RT

 PV = RT

Or, M =

Where P = pressure

        V = Volume

        T = temperature

        m = given mass

        M = molecular mass

        R = gas constant i.e 0.0821 L atm mol-1 k-1

Now substituting the values, the molar mass can be calculated as,

 M =

     =

     = 71.8869 g/mol 72 g/mol

Thus the molar mass is found to be 72 g/mol.