A carbon compound contains 12.8% Carbon, 2.1% Hydrogen, 85.1% Bromine. The molecular weight of the compound is 187.9. Calculate the molecular formula.

A carbon compound contains 12.8% Carbon, 2.1% Hydrogen, 85.1% Bromine.

1.	A carbon compound contains 12.8% Carbon, 2.1% Hydrogen, 85.1% Bromine. The molecular weight of the compound is 187.9. Calculate the molecular formula.
Answer» Solution :Step 1: Percentage composition of the ELEMENTS present in the COMPOUND. `{:(C,H,Br),(12.8,2.1,85.1):}` Step 2: Dividing with the respective atomic WEIGHTS of the elements. `{:((12.8)/(12),(2.1)/(1),(85.1)/(80)),(1.067,2.1,1.067):}` Step 3: Dividing by the smallest number to get simple atomic RATIO. `{:((1.067)/(1.067),(2.1)/(1.067),(1.067)/(1.067)),(1,2,1):}` The empirical formula is `CH_(2)Br` Empricial formula weight `12 + (2 xx 1) + 80 = 94` The molecular weight = 187.9 (given) `therefore n=(187.9)/(94)=2` `"The molecular formula" = "(empirical formula)"_(2)` `(CH_(2)Br)_(2)=C_(2)H_(4)Br_(2)`