Question

The optical rotation of an aqueous solution of a compound 'A' changes slowly due to slow fist order hydrolysis of ''A into 'B' and 'C' both of which are also optically active.specific rotations of A,B and C are +30degree, - 60degree and +50degree respectively. starting with pure 'A', the time taken for rotation to change from +30degree to 0degree is 20 minutes. calculate t1/2 of the reaction?

Answer 1

the amount of rotation is effectively measuring the concentration, the rate of change of degrees is, therefore, analagous to the change in concentration, which is the rate. Use the change in degrees to find the rate, and plug into the rate law equation for a first-order reaction\[R = k[A]^1\]to find k. then use the relationship between t1/2 and k