Saved Bookmarks
| 1. |
An organic compound contains C(30.6%), H(1.7%) and Br(67.7%). 0.706 g of this compound, when dissolved in 10g of acetone, increased the b.p. of acetone by 0.5^(@). If K_(b) for acetone is 1.67, find the molecular formula of the compound (Br=80). |
|
Answer» Solution :We have, `DeltaT_(b)= K_(b).m` `0.51.67 xx (0.706)/(M) xx (1000)/(10)` or M = 236 `{{:("M is the mol. wt. of the "),("ORGANIC COMPOUND"):}}` Now, in the given compound, moles of `C: H: Br= (30.6)/(12): (1.7)/(1): (67.7)/(80)` `=2.55 : 1.7: 0.84` `=3:2:1` `THEREFORE` empirical formula is `C_(3)H_(2)Br` (118) As the molecular weight is twice the empirical formula weight, molecular formula of the organic compound is `C_(6)H_(4)Br_(2)` |
|