Question

Chemistry

When 30 ml of a gaseous hydrocarbon is exploded with 200 ml of oxygen, the volume contraction after explosion was found to be 45 ml. On further treatment with alkaline pyrogallol there was a reduction of 95 ml. Find formula of the hydrocarbon.

Answer 1

Answer:

Step1: The hydrocarbon volume is 12ml.

Volume of Oxygen is 50ml.

The volume after the explosion is 32ml.

The volume left after KOH is 8ml.

Step2: When the hydrocarbon reacts with the oxygen it creates heat and the carbon di oxygen water. It is a combustion reaction. The reaction is given below. Let us assume the chemical formula of hydrocarbon is

CxHy+(x+y4)O2→xCO2+y2H2O

The volume of oxygen required to react with the hydrocarbon is

(x+y4)volumeofCxHy

=(x+y4)×12−−−−−−1

Step3. When the KOH is passed through the solution the carbon dioxide get absorbed. The volume left is only of Oxygen which is 8ml.

{50−12(x+y4)}+12x=32

On solving we get that the

y=50−323=6

Now we will write equation with only oxygen left

50−12(x+y4)=8

On solving we get

2x=32−8=2

Step4. So the value of x will be 2 and the value of y is 6 so the formula of hydrocarbon would be C2H6.