What is percent yield?
Percent yield measures the efficiency of a chemical reaction — how much product was actually obtained compared to the theoretical maximum.
% Yield = (Actual Yield / Theoretical Yield) × 100
A 100% yield is ideal but rarely achieved. Side reactions, incomplete reactions, and loss during purification reduce the actual yield.
Why is yield <100%?
- Side reactions produce unwanted byproducts
- Reversibility — equilibrium doesn't favor 100% products
- Loss during transfer — product left on glassware
- Purification — recrystallization, filtration lose some product