CxHyOz ==> xCO2 + 1/2yH2O
Convert g CO2 and g H2O to g C and g H.
0.561 g CO2 x (atomic mass C/molar mass CO2) = grams C.
0.316 g H2O x (2*atomic mass H/molar mass H2O) = grams H.
0.255 - g C - g H = grams O.
mols C = grams C/atomic mass C = ?
mols H = grams H/atomic mass H = ?
mols O = grams O/atomic mass O = ?
Now find the ratio of the elements to each other the smallest number being 1.00. The easy way to do that is to divide the smallest number by itself then divide the other numbers by the same small number. That will give you x,y,z for the empirical formula. Post your work if you get stuck.
An Unknown Compound (M=60.09 g/mol) is composed of Carbon, Hydrogen and Oxygen. Combustion of 0.255 g of the unknown compound produces 0.561 g Carbon Dioxide and 0.306 g of Water. Determine the molecular formula of the compound.
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