Question

the combustion of 0.202g of organic compounds produces 0.361g of CO2 and 0.147g of water. determine the molecular formula of compounds if it consists of C, H and O and has a molar mass of 184 g/mol

Answer 1

\[C _{x}H _{y}O _{z} + O _{2} -> CO _{2} + H _{2}O\]
0.202g 0.361g 0.147g

Answer 2

We know the unknown compound CxHyOz has a molar mass of 184g - so number of moles of the unknown compound used is : 0.202/184
Similarly number of moles of CO2 formed is 0.361/28
and number moles of H2O formed is 0.147/18

You can use the law of conservation of mass to find out the mass of O2 consumed and find the moles of O2 consumed.

Then use the property that molar ratio of the reactants is same as the number of molecules reacting in the reaction. You can then find the values of x, y and z