Percent Yield
Percent yield compares actual to theoretical yield.
About this topic
Percent yield compares the actual yield, the mass of product actually obtained in an experiment, to the theoretical yield, the maximum calculated from stoichiometry: percent yield = (actual ÷ theoretical) × 100. Yields below 100 % are common because of incomplete reactions, side reactions and product lost in transfers.
The theoretical yield comes from a stoichiometry calculation using the limiting reactant. The actual yield must be measured. Low yields may reflect reversible reactions that reach equilibrium, loss of material during filtering or washing, impure reactants, or competing reactions making by-products. Yields above 100 percent usually mean the product is wet or contaminated.
Worked example: a student predicts 12.0 g of product but isolates 9.6 g, so the percent yield is 9.6 / 12.0 x 100 = 80 percent. In drug manufacture, a multi-step synthesis with 80 percent in each of five steps gives only about 33 percent overall, which is why chemists work hard to improve each step.
Percent yield is key to cost and waste: the closer to 100, the more efficient and greener the process. It is also linked to atom economy. Students sometimes divide in the wrong order or use the reactant mass as the theoretical yield. Remember that actual yield can never beat conservation of mass.
Key ideas
- Actual ÷ theoretical × 100
- Losses in real experiments
- Rarely 100%
Quick check
Use cases: where Percent Yield helps
- Homework: review the key idea behind Percent Yield before you start a problem set.
- Exam revision: use the quick check to test whether you can recall Percent Yield without notes.
- Visual learning: play with the interactive lab to see how Percent Yield changes when you adjust its inputs.
- Teaching a friend: explain Percent Yield in your own words, then compare your version with the key ideas.
Chemistry explains medicine, food, cleaning products, fuels and building materials.
Frequently asked questions
What is Percent Yield?
Percent yield compares actual to theoretical yield.
What will I learn in Percent Yield?
Actual ÷ theoretical × 100. Losses in real experiments. Rarely 100%.
Is Percent Yield part of Chemistry?
Yes. It is one of 150 Chemistry topics on LearnViz HighSchoolEdu, with 3 key ideas, a live animation and a quick check.
Does the Percent Yield lab work on a phone or tablet?
Yes. The animation resizes to fit your screen and supports touch, so you can drag, tap and slide with your finger.
How should I study Percent Yield?
Read the summary and key ideas first, play with the interactive lab to see the idea in motion, then answer the quick check. If you get a question wrong, go back to the key idea it tests.
Do I need an account, and is my progress saved?
No account is needed. Marking a topic as learned is saved in your own browser, so it stays on that device and is not sent to a server.