Question

In the combustion reaction of alkanes if Ethane is used how many moles of oxygen are required?

(a) 3

(b) 4

(c) 7

(d) 3.5

The question was asked by my college professor while I was bunking the class.

My enquiry is from Hydrocarbons topic in section Hydrocarbons of Chemistry – Class 11

Answer 1

The correct choice is (d) 3.5

To explain I would say: The combustion reaction of alkanes has a standard reaction that is CnH2n+2 + (3n/2 + 1/2)O2 → nCO2 + (n + 1)H2O. In the case of combustion of ethane, n = 2. That means the number of moles of oxygen required is 3(2)/2 + 1/2 = 3.5