If I know that a 16.00gram sample of methane contains 12.00grams of carbon and 4.00grams of hydrogen and 56.00grams sample of ethylene contains 48.00 grams of carbon and 8.00grams of hydrogen, how can I derive the chemical formula CH4 for methane and C2H4 for ethylene using the Law of Multiple Proportions?

Question

anonymous · Answer

12 grams of carbon in the methane sample are 1 mol of carbon, while 4 grams of hydrogen in the same sample are 4 mol of hydrogen - then the ratio between carbon and hydrogen is 1:4 and the formula is CH4.

48 grams of carbon in the ethylene sample are 4 mol of carbon, while 8 grams of hydrogen in the same sample are 8 mol of hydrogen - then the ratio between carbon and hydrogen is 4:8 or 1:2 and the formula is CH2 or C2H4.