Brainlag PlusHow much product you really get compared with the most you could, how many of the starting atoms end up in that product, and how industry weighs the two.
Percentage yield
The theoretical yield is the most product the reactants could make, worked out from the equation.
The actual yield is what you collect.
percentage yield = mass of product actually made ÷ maximum theoretical mass × 100
All boards (Chemistry only): recall this.
- Heating 25.0 g of CaCO₃: theoretical mass of CaO = 25.0 ÷ 100 × 56 = 14.0 g
- actual mass collected = 11.9 g
- percentage yield = 11.9 ÷ 14.0 × 100 = 85.0%
Yields fall below 100% because:
- the reaction may be reversible, so it never goes to completion
- some product is lost when it is filtered, poured or dried
- some reactants take part in side reactions that make other products
The rest of this lesson and its 12 practice questions are in Plus.
Screen 1 of 4, free to read.
- 12 exam-style questions, marked as you go, each with a worked solution
- Anything you get wrong is saved to your flashcards