Question

A hydrocarbon 15ml is combusted with 375 ml of air, which
contains 20% oxygen. after combustion total vol of gases is 330ml What will be the formula of hydrocarbon?​

Answer 1

Answer:

Combustion of hydrocarbon is given by chemical equation ..

equation is in the above image

here, it is clear that,

1vol of hydrocarbon reacts with (x + y/4) vol of O2 to form x vol of carbon dioxide.

so, 15ml hydrocarbon reacts with 15(x + y/4) ml of oxygen to form 15x ml of carbon dioxide.

volume of O2 = 20% of 375ml

= 20 × 375/100 = 75 ml

so, 15(x + y/4) = 75

x + y/4 = 5 .....(1)

a/c to question, final volume of gases = 330ml

initial volume of gases = 375ml + 15ml = 390ml

amount of water formed = 390ml - 330ml = 60ml

so, 15 × y/2 = 60 => y = 8

put it in equation (1), x = 3

so, hydrocarbon is

C3 H8