If a mixture contains 75% of one compound and 25% of its enantiomer, what is the e.e. of the mixture?

A) 100
B) 75
C) 50
D) 25
E) 3

The e.e. (enantiomeric excess) of a mixture can be calculated as follows:

e.e. = (% major enantiomer) - (% minor enantiomer)

In this case, the major enantiomer is the compound that makes up 75% of the mixture, and the minor enantiomer is its enantiomer, which makes up 25% of the mixture.

e.e. = (75) - (25)
e.e. = 50

Therefore, the e.e. of the mixture is 50%. Answer choice C is the correct answer.