Question

Pentane is burnt with 100% of excess air, what is the percentage of H2O in the products?

(a) 12.4%

(b) 34.6%

(c) 42.1%

(d) 56.9%

I have been asked this question in examination.

The origin of the question is Material Balances Involving Combustion in portion The Chemical Reaction Equation & Stoichometry, Material Balances for Processes Involving Reaction and Multiple Units of Basic Chemical Engineering

Answer 1

Right option is (c) 42.1%

To explain: The reaction is C5H12 + 8O2 -> 5CO2 + 6H2O. Basis: 10 moles of C5H12, => moles of O2 reacted = 80, => moles of O2 entered the process = 160, => moles of CO2, H2O and O2 in products are 50, 60 and 80, => percentage of H2O = 80/190*100 = 42.1%.