Question

Many homes in rural America are heated by propane gas, a compound that contains only carbon and hydrogen. Complete combustion of of a sample of propane produced 2.641 grams of carbon dioxide and 1.422 grams of water as the only products. Find the empirical formula.

Answer 1

moles CO2 = 2.641/44.01 = 0.06.
One mole C to mole CO2 = 0.06 moles C.

moles H2O = 1.422/18.015 = 0.0789
moles H = 2x moles H2O = 2x0.789=0.158 moles H.

Find the ratio of each that has small whole numbers. The easy way to do this is to divide the smaller value by itself; then divide the other number by the same small value.
C = 0.06/0.06 = 1
H = 0.158/0.06 = 2.633
2.63 is too far away from a whole number to round so try multiplying by whlle numbers; i.e., try 2, 3, 4, etc. and find one that produces two whole numbers when rounded. I think 3 will do the trick.

Answer 2

C3H8