The concentration of a solution can be calculated using the equation concentration of solution = mass of solid / volume of solution A student dissolved 9.25g of ammonium chloride in water and made up the solution to a volume of 200 cm³ - Edexcel - GCSE Chemistry Combined Science - Question 5 - 2021 - Paper 1

Substituting the values into the concentration formula:

$ext{concentration} = \frac{\text{mass of solid}}{\text{volume of solution}} = \frac{9.25 ext{ g}}{0.200 ext{ dm}^3}$

Now perform the calculation:

$\text{concentration} = \frac{9.25}{0.200} = 46.25 ext{ g dm}^{-3}$