A student prepares magnesium chloride, MgCl2\text{MgCl}_2MgCl2, by reacting magnesium hydroxide, Mg(OH)2\text{Mg(OH)}_2Mg(OH)2, with dilute hydrochloric acid, HCl\text{HCl}HCl.
This is the equation for the reaction:
Mg(OH)2+2HCl→MgCl2+2H2O \text{Mg(OH)}_2 + 2\text{HCl} \rightarrow \text{MgCl}_2 + 2\text{H}_2\text{O} Mg(OH)2+2HCl→MgCl2+2H2OThe student obtains 14.5 g14.5\text{ g}14.5 g of magnesium chloride. The percentage yield for this preparation is 85%85\%85%.
Calculate the mass of hydrochloric acid the student used in the reaction.
Give your answer to 3 significant figures.
Relative atomic mass (ArA_rAr): H=1.0\text{H} = 1.0H=1.0 \quad O=16.0\text{O} = 16.0O=16.0 \quad Mg=24.3\text{Mg} = 24.3Mg=24.3 \quad Cl=35.5\text{Cl} = 35.5Cl=35.5
91 exam-style questions on OCR GCSE Chemistry Monitoring chemical reactions. Each one has a worked solution and a mark scheme showing where the marks go.