Looking for the calculations to part a Please do not answer otherwise (Resubmitt
ID: 899526 • Letter: L
Question
Looking for the calculations to part aPlease do not answer otherwise (Resubmitted question)
B2. Kinetic resolution in organic chemistry was first reported in 1899, for the esterification of racemic mandelic acid with optically active ()-menthol. An excess of racemic acid resulted in faster esterification of the (+)-mandelic acid than the ester from ()-mandelic acid. Under certain conditions, the activation energy for esterification of the () mandelic acid is reduced to 1.2 kJ mol in the presence of racemic acid, and the activation energy for esterification of the (-)-mandelic acid is 1.3 kJ mo a) Calculate the maximum percentage yield of the ester from (+)-mandelic acid at 300 K. (You should assume that the Arrhenius prefactor, A, is the 7 marks] b) Calculate the temperature at which you would carry out the reaction in Explain the physical reason for the direction of this change, with reference 6 marks] same for both reactions. R = 8314 J K-l mol -1 order to achieve 99% yield. to the Arrhenius equation.
Explanation / Answer
B2)a)
Reaction constant K for the +mandelic acid = Ae^(-Ea/RT)
=Ae^(-1.2/(8.313*300))
=0.999519 A
Reaction constant K for the -mandelic acid = Ae^(-Ea/RT)
=Ae^(-1.3/(8.313*300))
=0.999479 A
so percentage of from +mandelic acid = (0.999519*100)/(0.999519+0.999479)
=50.001%
b)let the temprature be T kelvins.so,
percentage= e^(-1.2/(8.313*T))*100/(e^(-1.2/(8.313*T))+e^(-1.3/(8.313*T)))
differentiating with respect to T and equating it to 0,
solving, we get T=166.26 K
the physical reason it that the the temperature will be low hence the reaction with the slower speed will be formed less and the reaction with the fast speed will proced to completion
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