Question

an organic compound contains C , H and O. in one combustion analysis, 10.71 g of this compound yields 6.41 g of H2O and 15.72 g of CO2. Calculate the number of carbon atoms in this organic compound if the molar mass of the compound is 146 g/mol

Answer 1

Find the formula as follows:
g C = g CO2 x atomic mass C/molar mass CO2 = approx 4
g H = g H2O x 2*atomic mass H/molar mass H2O = approx 0.7
g O = g compound - g C - g H = approx 6

mols C = g C/atomic mass C = approx 0.35
mols H = g H/atomic mass H = approx 0.7
mols O = g O/atomic mass O = approx 0.35 so the ratio is
CH2O for the empirical formula and 30 is the empirical mass.
molecular formula is 146/30 = 4.9 so round to 5 and the molecular formula is C5H10O5. My assumption is that the 146 is an approx molar mass but it is 150 from the molecular formula.
mols compound is 10.71/150 = x
C atoms = x*6.02E23*5