20cm3 of a gaseous hydrocarbon were mixed with 90cm3 oxygen and the mixture exploded.At rom temp,60cm3 of gas?

Question

pls help me out with this.20cm3 ofa gaseous hydrocarbon were mixed with 90cm3 oxygen,and the mixture xploded.At room temp,60cm3 of gas were left.40cm3 of the gas CO2 were absorbed by sodiumhydroxide ,leaving 20cm3 of oxygen.Find the empirical formula of the hydrocarbon.

Answer 1

20cm3 of the hydrocarbon formed 40cm3 of CO2, so there must be 2 x C atoms present.

The 20cm3 of the hydrocarbon reacted with 70cm3 of oxygen, so the ratio of hydrocarbon: O2 is 2:7.

From this you can start to build up a combustion equation, with 2:7:4 ratios of hydrocarbon:O2:CO2.

You should now be able to work out the number of H atoms as 6, ie the empirical formula is CH3.