Question

The specific rotation, (a)p, for (+)-alanine is +8.5. What is the observed rotation for a solution of 1.7 g of (+)-alanine in 10 mL of water in a sample tube having a pathlength of 10 cm? degrees The observed rotation of a solution of 1.3 g of a compound in 10 mL of water is +8.2 degrees. If the pathlength is 10 cm, what is the specific rotation of the compound?

Answer 1

The specific rotation of substance = optical rotation/concentration of the substance (gm/mL)* path length in dm

1. --The optical rotation of the substance

= specific rotation of substance*concentration of the substance (gm/mL)* path length in dm

= (8.5 *1*1.7)/10 = 1.445 degrees

^---The specific rotation of substance = 8.2/(1.3*1/10) = 63.07 degrees.

2. -The optical rotation of the substance = (-52*1*0.33/10) = -1.716 degrees.

    The specific rotation of substance = 13/(1.4*1/10) = 92.85 degrees.

3. The optical rotation of the substance = (12*1*1.6/10) = 1.92 degrees.

The specific rotation of substance = (-6.9)/(1.2*1/10) = - 57.5 degrees.