lesson
State which quantity the calculation measures
1 · Learn
Mass concentration is mass of dissolved solute divided by final solution volume in compatible units. Percentage yield compares actual product obtained with the theoretical amount for the stated reaction and inputs. These are different calculations.
Use solution volume rather than assuming solvent volume is always unchanged. A yield below 100% can reflect incomplete reaction, competing reactions or losses during separation.
2 · Worked example
10 g in a final 0.5 dm³ solution gives 20 g/dm³. Obtaining 8 g when 10 g is theoretically expected gives 80% yield.
3 · Your turn
Calculate percentage yield for actual 12 g and theoretical 15 g.
Check your answer
80%.
4 · Apply your learning
Identify which supplied measurements are needed for concentration and which for yield before calculating.
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Check a calculation · Year 5 onward
Use this only when your teacher or adult allows a calculator for the task. Show your thinking first. It does not replace mental or written arithmetic and does not mark your lesson answer.
Powers, roots and trigonometry · Year 7 onward
Use only when the task allows a calculator. Choose one operation at a time and record your working. Trigonometry here always uses degrees (DEG), not radians. Inverse sine, cosine and tangent return an angle, not a reciprocal. Keep exact fractions and π in answers when requested.
Approximate numerical results use up to 12 significant digits. Inverse sine returns −90° to 90°, inverse cosine 0° to 180°, and inverse tangent −90° to 90°; these are principal values, not every possible solution of a trigonometric equation.
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