Chemistry · Oct / Nov 2022 · Paper 11 · Question 22

The rate of reaction between magnesium and dilute hydrochloric acid is investigated. The equation is shown. Mg(s) + 2HCl(aq) → MgCl2(aq) + H2(g) A known mass of magnesium is added to an excess of dilute hydrochloric acid. The concentration of the hydrochloric acid and the volume of hydrogen produced is measured at regular time intervals. Which pair of graphs correctly shows the experimental results?

1. Aconcentration of HCl decreases to zero; volume of hydrogen increases and levels off
2. Bconcentration of HCl decreases to zero; volume of hydrogen increases with increasing gradient
3. Cconcentration of HCl decreases and levels off above zero; volume of hydrogen increases with increasing gradient
4. Dconcentration of HCl decreases and levels off above zero; volume of hydrogen increases and levels off

As printed in the paper