This question is about iron - AQA - GCSE Chemistry Combined Science - Question 8 - 2018 - Paper 1

Unreacted iron can be separated from the mixture by using a magnet to attract the iron particles.

To calculate the mass of iron produced:

1. Calculate the moles of magnesium used: $ext{Moles of Mg} = \frac{0.120 \text{ g}}{24 \text{ g/mol}} = 0.005 \text{ moles}$

2. According to the reaction, 3 moles of Mg produce 2 moles of Fe: $\text{Moles of Fe produced} = 0.005 \text{ moles Mg} \times \frac{2 \text{ moles Fe}}{3 \text{ moles Mg}} = 0.00333 \text{ moles Fe}$

3. Calculate the mass of Fe produced: $\text{Mass of Fe} = \text{Moles of Fe} \times 56 \text{ g/mol} = 0.00333 \text{ moles} \times 56 \text{ g/mol} = 0.1866 \text{ g}$

4. Convert mass to mg: $0.1866 \text{ g} = 186.6 \text{ mg}$

Hence, the mass of iron produced is approximately 187 mg.

In the reaction between magnesium and iron chloride, iron (Fe³⁺) is reduced. The reduction can be represented by the half-equation: $\text{Fe}^{3+} + 3\text{e}^- \rightarrow \text{Fe}$ This equation shows that iron ions gain electrons to form solid iron.