A teacher investigates the reaction between hydrochloric acid and calcium.
The diagram shows the setup:
- The teacher uses five different concentrations of hydrochloric acid.
- Each time they react the hydrochloric acid with 0.2 g0.2\text{ g}0.2 g of calcium turnings.
- They repeat the experiment with 0.2 g0.2\text{ g}0.2 g of calcium powder.
The table shows the teacher's results:
| Concentration of hydrochloric acid (mol/dm3\text{mol/dm}^3mol/dm3) | Time for calcium to react (s\text{s}s): Calcium turnings | Time for calcium to react (s\text{s}s): Calcium powder |
|---|---|---|
| 0.4 | 184 | 98 |
| 0.8 | 122 | 65 |
| 1.2 | 64 | 35 |
| 1.6 | 41 | 20 |
| 2.0 | 28 | 11 |
The teacher says that the reaction is faster with calcium powder than with calcium turnings.
Use the results to explain why the teacher is correct.
Describe how the rate of reaction changes when the concentration of the hydrochloric acid increases.
Explain your answer to (i) using ideas about particles.
The teacher used 0.2 g0.2\text{ g}0.2 g of calcium.
0.2 g0.2\text{ g}0.2 g of calcium reacts with hydrochloric acid to make 0.010 g0.010\text{ g}0.010 g of hydrogen gas.
A student suggests that the rate of reaction could be investigated by measuring the loss in mass during the reaction.
Suggest why this method would not work well.
Describe the test for hydrogen gas.
In another experiment, the teacher reacts 0.56 g0.56\text{ g}0.56 g of iron with excess hydrochloric acid.
Fe+2HCl→FeCl2+H2\text{Fe} + 2\text{HCl} \rightarrow \text{FeCl}_2 + \text{H}_2Fe+2HCl→FeCl2+H2
Calculate the mass of hydrogen gas made.
Relative atomic mass (ArA_rAr): H=1.0\text{H} = 1.0H=1.0, Fe=56.0\text{Fe} = 56.0Fe=56.0
Controlling reactions Questions
Practise OCR GCSE Chemistry Controlling reactions with exam-style questions for Foundation and Higher tier. 56 questions, matched to the OCR GCSE Chemistry (J248) specification and written in Paper 1 and Paper 2 (Foundation Tier) or Paper 3 and Paper 4 (Higher Tier) style. Every question includes a full worked solution and mark scheme, so you can see where marks are awarded rather than just whether you got the answer right.