Fractional vs Simple distillation After performing both simple and fractional distillations for a 50/50 mixture of methyl acetate/ethanol, i discovered that my total recovery (in mass) of substances after distillation was lower for the fractional distillation than for the simple distillation. Is this to be expected, or would it be because of an error on my behalf? (To clarify, my initial mass for F. distillation was 17.39g and my recovered mass was 14.95g. My initial mass for S. distillation was 16.54g and my recovered mass was 16.04g.) What would be some reasons in explaining this result?
In practice distillation is not 100% efficient: You never get a perfect separation of a mixture.  But fractional distillation is more efficient, so you would expect the product to be of higher purity than that produced by simple distillation.

E.g., if you have a 50/50 mixture by mass of two liquids, you would expect a higher concentration of the higher-boiling-point liquid at the end of a fractional distillation apparatus, which means a smaller fraction of the original mass.