Milk of magnesia containing magnesium hydroxide, Mg(OH)2\text{Mg(OH)}_2Mg(OH)2, is used to neutralise spillages of hydrochloric acid, HCl\text{HCl}HCl.
The equation for the reaction is:
Mg(OH)2(s)+2HCl(aq)→MgCl2(aq)+2H2O(l) \text{Mg(OH)}_2(\text{s}) + 2\text{HCl}(\text{aq}) \rightarrow \text{MgCl}_2(\text{aq}) + 2\text{H}_2\text{O}(\text{l}) Mg(OH)2(s)+2HCl(aq)→MgCl2(aq)+2H2O(l)A student investigates how much magnesium hydroxide is needed to neutralise 250 cm3250\text{ cm}^3250 cm3 of hydrochloric acid with a concentration of 0.150 mol/dm30.150\text{ mol/dm}^30.150 mol/dm3.
He uses 0.90 g0.90\text{ g}0.90 g of magnesium hydroxide.
Calculate the amount, in moles, of HCl\text{HCl}HCl in the hydrochloric acid.
Calculate the amount, in moles, of Mg(OH)2\text{Mg(OH)}_2Mg(OH)2 used by the student. [Mr of Mg(OH)2=58M_{\text{r}}\text{ of }\text{Mg(OH)}_2 = 58Mr of Mg(OH)2=58]
Explain whether the student used the right amount of magnesium hydroxide to neutralise the hydrochloric acid.
80 exam-style questions on Edexcel IGCSE Chemistry Chemical formulae, equations and calculations. Each one has a worked solution and a mark scheme showing where the marks go.