A hydrocarbon CxHy mass ratio between hydrogen and carbon 1: 10.5 Onelitre of hydrocarbon at 123 degree Celsius and 1 atmospheric pressure waves 2.6 gram find the molecular formula of the hydrocarbon

PV=nRT=  

M

w

RT

or 1=  

M

2.8

×0.0821×400

or M=91.95≈92

Let the formula be C  

a

H  

b

.  

So 12a+b=92

b

12a

=10.5(given)

11.5b=92

or b=8

∴ a=7

Therefore, the formula is C  

7

H  

8

.

molar mass = 12*7+1*8 = 92gm/mole

Explanation: