Question

Please show all steps and explain, as I need to understand for an exam. Thx!

14. The combustion of a hydrocarbon produces 66.02 g CO2 (molecular weight 44.01 g/mol) and 13.51 g H2O (molecular weight 18.01 g/mol). It's empirical formula must be: A. CH B. C2H C. CH2 D. C3H2 E. none of the above. ANSWER: A

Answer 1

A hydrocarbon when burnt produces carbon dioxide and H₂O

Given,mass of CO₂ = 66.02 gm

Molar mass of of CO₂ =44.01

Given mass of H₂O = 13.51 gm

Molar mass of H₂O =18.01

Number of moles of CO₂ = given mass/molar mass =66.02/44.01 = 1.5 mol

Number of moles of H₂O =13.51 /18.01 =0.75

In every reaction of combustion of hydrocarbon,production of CO₂ and H₂O is 1:2 ratio

Example--- CH₄ + O₂ ------> CO₂ + 2H₂O

Therefore above moles will be in 1:2 ratio

For 1.5 mol of carbon dioxide, (2× 0.75 ) 1.5mol of H₂O is also produced

So ratio of number of moles of both are 1:1

Therefore empirical formula = CH