CALCULATING THE EMPIRICAL FORMULA OF ORGANIC COMPOUNDS!!!

The empirical formula of an organic compound (any substance that contains carbon) can be found by:
-burning the compound (react with O2)
-collecting and weighing the products
-from the mass of the products, the moles of each element in the original organic compound can be calculated


Ex. 5g of sample→15.0g of CO2 & 8.18g of H2O
     
      CxHy+zO2→xCO2+y/2H2O
     
      this is the balanced chemical equation for the burning of CxHy
      
      the moles of C and H in CxHy=moles of C in CO2 and the moles of H in H2O
     
     15g*(1mole/44g)=0.341mole C      8.18g*(1mole/18.02g)=0.454mole water*2=0.908mole H
      
     0.908 moles of H and 0.341 moles of C must have been in the original substance
CxHy=C0.341H0.908
    
    Carbon: 0.341/0.341=1           Hydrogen=0.908/0.341=2.66*3=8
     
    Empirical Formula=C3H8
      
    *always check the masses