Reaction Yield Percent

Reaction yield: %yield = (actual / theoretical) × 100%

Percent yield tells you how much product a synthesis actually hands you versus the maximum that stoichiometry predicts: %yield = (actual mass / theoretical mass) · 100%. When it lands below 100%, the usual culprits are incomplete conversion, side reactions, material lost during workup (filtration, extraction, recrystallisation), and equilibrium limits. Say a procedure should give 10 g of product on paper but you only isolate 8.5 g. That is 85% yield. For reference, anything above 90% is excellent, 60–90% is what industrial pharmaceutical synthesis tends to see, and modern green-chemistry routes push toward near 100% on both atom economy and isolated yield.

Applications

Tuning processes in industrial chemistry. Pharmaceutical manufacturing, where a single percentage point can mean serious money. QA labs checking that batches stay consistent. Undergraduate teaching labs grading how well a procedure was run. And comparing routes during medicinal-chemistry scale-up.

FAQ

What does "atom economy" add to yield? It measures the fraction of reactant atoms that actually make it into the product, leaving by-products out. You can hit 100% yield and still throw away a lot of raw material if the atom economy is poor.

Why does my yield drop after recrystallisation? Some of your product stays dissolved in the mother liquor and gets tossed out along with the impurities. You end up with a purer solid but less of it.

Is theoretical yield the same as limiting-reagent yield? Yes, they are one and the same. You always work out theoretical yield from the moles of the limiting reagent and the product's stoichiometric coefficient.