To determine the molecular weight of the given substance by Rast method.
The molecular weight of a non-volatile substance is determined by Rast method employing the principle of depression of freezing point. The following equation is applicable.
where m = mol. wt. of the solute, Kf = molar depression constant of the solvent, w = weight of the solute in gram, W = weight of the solvent in gram and ∆Tf = depression in freezing point of the solvent.
APPARATUS AND MATERIALS
- A small Pyrex or Corning tube.
- Sulphuric acid or liquid paraffin or glycerine bath.
- Thin glass rod.
- Thiele's tube.
- Thermometer with the calibration ...