Calculate the percentage by mass of potassium in potassium carbonate, K2CO3\text{K}_2\text{CO}_3K2CO3.
percentage by mass of element=total relative atomic mass of elementrelative formula mass of compound×100 \text{percentage by mass of element} = \frac{\text{total relative atomic mass of element}}{\text{relative formula mass of compound}} \times 100 percentage by mass of element=relative formula mass of compoundtotal relative atomic mass of element×100(Relative atomic masses: C=12\text{C} = 12C=12, O=16\text{O} = 16O=16, K=39\text{K} = 39K=39)
258 exam-style questions on Edexcel GCSE Chemistry Calculations involving masses. Each one has a worked solution and a mark scheme showing where the marks go.