Question

Complete combustion of 3.30 g of a hydrocarbon produced 9.99 g of CO2 and 5.11 g of H2O. What is the empirical formula for the hydrocarbon?

Answer 1

all the carbon ends up in CO2 (notice how there is no other carbon product) and all the hydrogen ends up in H2O (notice how there is no other hydrogen product)

so 9.99g CO2 ---> convert to moles CO2 ---> that's how many moles carbon in the original hydrocarbon

same logic with 5.11g H2O ---> convert to moles H2O ---> that's how many moles hydrogen in the original hydrocarbon

from there, empirical formula can be derived from the mole ratio of carbon to hydrogen