Question

One mole of a hydrocarbon contains 36g of carbon and it's vapour density is 20. What is the structure of the hydrocarbon. Please show working?

Answer 1

If it is a hydrocarbon then it must be of the form $C_xH_y$

As the question says one mole of the hydrocarbon contains 36 g of carbon then it contains 3 moles of carbon which means that the value of x=3

we are given that the vapour density is 20 which means molecular weight is 40 (molecular wight = 2 x vapour density )

we are already given mass of carbon in the compound is 36 which means remaining is of hydrogen which is equal to (40-36)=4g

which means that hydrogen atom will be equal to 4

$C_3H_4$