Pearson Edexcel IAL Chemistry 1.5 Solution concentration

Practise solution concentration calculations by linking mass, moles, volume and ion ratios in mol dm^-3 and g dm^-3 contexts.

Exam points

calculate mol dm^-3 from mass and volume, converting cm^3 to dm^3 accurately
find moles of ions in solution by combining concentration, volume and formula ratios
use concentration and balanced equations to determine required volumes or precipitating amounts

[Maximum number: 1]

This question is about magnesium, magnesium oxide and magnesium sulfate.

Hydrated crystals of magnesium sulfate, $\mathrm{MgSO}_{4} \cdot 7 \mathrm{H}_{2} \mathrm{O}$ , can be made by reacting magnesium with sulfuric acid.

In an experiment, magnesium was added to $30.0 \mathrm{~cm}^{3}$ of $0.500 \mathrm{~mol} \mathrm{dm}^{-3}$ sulfuric acid.
$\left[M_{\mathrm{r}}\right.$ value: $\mathrm{MgSO}_{4} \cdot 7 \mathrm{H}_{2} \mathrm{O}=246.4 \quad A_{\mathrm{r}}$ value: $\left.\mathrm{Mg}=24.3\right]$

Calculate the number of moles of sulfuric acid used in this experiment.

number of moles of sulfuric acid

Example of calculation
$30 \times 0.5 \div 1000=0.015 / 1.5 \times 10^{-2}(\mathrm{~mol})$

Do not award 1 SF .

(1)

All question bank results loaded

1.5—The concentration of a solution in mol dm−3 and g dm−3 Titration calculations are not required at this stage question 1