又一條mole problem...

Newcastle Fans

60 cm3 of a gaseous mixture of methanol, propene and methane were mixed with 325 cm3 of oxygen and then ignited. The mixture, on cooling back to the original temperature (75C) was found to have a contraction of 115 cm3, a furthur contraction of 80 cm3 occured on treatment with potassium hydroxide solution. Assuming constant pressure throughout, find the composition by volume of the original mixture.

(I know that the cooling will bring about the condensation of water vapuor produced, and potassium hydroxide solution will absorb the carbon dioxide produced. But how to calculate the composition? Thanks.)

Newcastle Fans

Another question:

When 15 cm3 of a gaseous hydrocarbon H were mixed with 70 cm3 of oxygen (in excess) and ignited inside a graduated tube in the presence of concentrated sulphric acid, the volume of the residual gas was 47.5 cm3. This was reduced to 17.5 cm3 by treatment with potassium hydroxide. All volumes were measured under the same temperature and pressure. Find the molecular formula of H.

alexgiggs

in this question
u should write down all the chemical eq.
and  the volume used is proportional to the mole ratio of them~