Answer:
In stereochemistry, the enantiomeric excess (ee) of a substance is a measure of how pure it is. In this case, the impurity considered is the unwanted enantiomer: the mirror image of a chiral compound.
Which is 60% in this case
Explanation:
total mass of the mixture is = 10.09g
% of (-)-glyceraldehyde = 8.09/10.09 = 80%
by the same way, the % of ( )-glyceraldehyde is = 20%
the enantiomeric excess (e.e) are
e.e = %(-)-glyceraldehyde - %( )-glyceraldehyde
e.e = 80% - 20% = 60%
