Question

4. 0.050 g of sample is dissolved in 2.0 mL of ethanol, and this solution is placed in a 2.0-cm polarimeter tube. The observed rotation is clockwise 0.043. Calculate the specific rotations taken at 25°C using the sodium D line.

Answer 1

Specific rotation and observed rotation both are properties of chiral molecules. Specific notation is a fundamental property of Chinal compound by which The orientation of a plane polarized mono-chromatic light is changed by a certain amount as the light passes through the sample of a solution. We know that - E s pecific notation &= obsesived rotation - Concentration in gr/ml = path length or length of cell in dm. - Эn The qug Ation - 0.05 gm of sample is dissolved in 2 ml of ethanol. c= 0.05 gm/ml = 0.025 gm sini length of cell = 2 cm = 0. 2dm.

Observed rotation =C+0.043º. [ 1 - 4300 430 (+)0·0430 6 0·025 x 0.2 [ 2 ] 25 = (+) 8.60 : Specific notation = (6) 8.60