Empirical Formula of Compound

Empirical Formula of Compound

The characteristic order of pineapple is due to ethyl butyrate, a compound containing carbon, hydrogen, and oxygen. Combustion of 4.17 mg of ethyl butyrate produces 9.48 mg of co2 and 3.87 mg of h2o. What is the empirical formula of the compound?

As we know, the empirical formula of Ethyl Butyrate is = CxHyOz 
Now the atomic weight of these molecules are, 
C = 12
H = 1
O = 16
Therefore, the weight of 1 mol of CO2 is = (12+ 2*16) gm.
                        = 44 gm.
Now, this shows that, 44 gm. of CO2 is = 1 mol CO2
Therefore, 44 mg CO2 is = 1 m mol CO2
Therefore, 9.48 mg CO2 refers to = 9.48/ 44 m mol of CO2
                    = 0.215 m mol of CO2
Now, in 1 mol of CO2, there is 12 mg of carbon.
Therefore, in 0.215 mol of CO2, the amount of carbon is = 12* 0.215 mg.
                                = 2.58 mg of carbon.
Similarly, the weight of 1 mol of H2O, is = (2*1 + 16) gm.
                        = 18 gm.
Therefore, similarly it can be considered that 18 gm. of H2O is = 1 mol of H2O.
Therefore, 18 mg of H2O is = 1 m mol of H2O.
Therefore, 3.87 mg. of H2O is = 3.87/ 18 m mol of H2O.
                    = 0.215 m mol of H2O.
Now, it can be said that, in 1 m mol of H2O the amount of Hydrogen is = 2 mg.
Therefore, in 0.215 m mol of H2O, the amount of Hydrogen is = 2* 0.215 mg.
                                    0.43 mg.
So, in 4.17 ethyl butyrate the amount of Oxygen is = {4.17 – (2.58 + 0. 43)} mg.
                            = 1.16 mg.
Now, since the valence of Carbon, Hydrogen and Oxygen had been assumed x, y, and z respectively, 
Therefore, x: y: z = 2.58/ 12 : 0.43/ 2 : 1.16/ 16
            = 2.96: 5.93: 2 …. (upon calculation)
Therefore, x: y: z = 3: 6: 2
Therefore, the empirical formula of Ethyl Butyrate is, C3H6O. Read more question answer like this one at Assignmenthelp.us.