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Calculating percentage yield
Syllabus HAVO: Quantities and relationships
Question 1 / 50 correct
29.0 g is weighed although at most 27.2 g of pure product is possible. What could explain this?
More explanation and a worked example
A maximum and a measurement
The theoretical yield follows from the reaction ratio and limiting reactant. The actual yield is the amount of pure product obtained. Percentage yield = actual / theoretical × 100%.
More than 100% needs an explanation
A wet or impure product can give an excessive measured mass. This does not prove extra conversion. Percentage yield is also different from energy efficiency or atom economy.
Theoretically 1.60 mol NH₃ forms. M = 17.0 g/mol. You collect 20.4 g.
- Theoretical mass = 1.60 × 17.0 = 27.2 g.
- Percentage yield = 20.4 / 27.2 × 100%.
Sources for this topic
- Chemistry HAVO 2026, version 4 (July 2025) · Quantities and relationships · p. 21–22 · R&A1