Consider the reactions: A --(K1=6.93×10^-2 min^-1)-- B and A --(K2=13.86×10^-2 min^-1)-- C. A, B and C all are optically active compounds. If the optical rotations of A, B and C per unit concentrati

Question

Consider the reactions: A --(K1=6.93×10^-2 min^-1)--> B and A --(K2=13.86×10^-2 min^-1)--> C. A, B and C all are optically active compounds. If the optical rotations of A, B and C per unit concentration are 60°, -72° and 42°, respectively, and the initial concentration of A is 2 M, then

Prashant Kotian · Accepted Answer

Correct answer: A,D. K_total = 20.79×10^-2 min^-1. t1/2 = ln 2 / K_total = 3.33 min. At t=inf, [B] = 2/3 M and [C] = 4/3 M. Rotation = (2/3)(-72) + (4/3)(42) = +8° (dextrorotatory). At 75% conversion, [A] = 0.5 M, [B] = 0.5 M, [C] = 1.0 M. Rotation = 0.5(60) + 0.5(-72) + 1.0(42) = +36°. Therefore, correct answer is A,D.

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