A farmer uses ammonium nitrate, NH4NO3\mathrm{NH_{4}NO_{3}}NH4NO3, as a fertiliser to add nitrogen to the soil.
Relative atomic masses: H = 1, N = 14, O = 16
Give the number of different elements in ammonium nitrate.
Give the total number of atoms in the formula NH4NO3\mathrm{NH_{4}NO_{3}}NH4NO3.
Calculate the relative formula mass (MrM_{r}Mr) of ammonium nitrate.
Calculate the percentage by mass of nitrogen in ammonium nitrate. Use the equation: percentage by mass of an element =total Ar of that element in the formulaMr×100\displaystyle = \frac{\text{total } A_{r} \text{ of that element in the formula}}{M_{r}} \times 100=Mrtotal Ar of that element in the formula×100
The table shows the percentage by mass of nitrogen in three fertilisers.
| Fertiliser | Percentage by mass of nitrogen (%) |
|---|---|
| ammonium nitrate | 35.0 |
| ammonium sulfate | 21.2 |
| urea | 46.7 |
The farmer wants the fertiliser that supplies the most nitrogen in each 1 kg bag. Give the name of the fertiliser the farmer should choose.
55 exam-style questions on Edexcel GCSE Chemistry 2.6 Calculations involving masses, covering 2.6.1 Relative formula mass and percentage composition, 2.6.2 Empirical and molecular formulae, 2.6.3 Conservation of mass, 2.6.4 Reacting masses and concentration in g dm⁻³, 2.6.5 The mole and the Avogadro constant, and 2.6.6 Limiting reactants and stoichiometry. Each one has a worked solution and a mark scheme showing where the marks go.