A student uses this apparatus to investigate the rate of reaction between magnesium and an excess of dilute hydrochloric acid.
She uses this method.
- use a graduated beaker to pour 50 cm3 of dilute hydrochloric acid of concentration 2.00 mol / dm3 into the conical flask
- add a piece of magnesium ribbon of mass 0.086 g to the acid and put the bung into the neck of the flask
- measure the total volume of gas collected every ten seconds until the reaction stops
The table shows the student's results.
Time in s | Volume of hydrogen in cm3 |
0 | 0 |
10 | 29 |
20 | 52 |
30 | 67 |
40 | 76 |
50 | 81 |
60 | 84 |
70 | 84 |
80 | 84 |
- 0.043 g of magnesium ribbon
- 50 cm3 of 2.00 mol / dm3 hydrochloric acid
- 0.086 g of magnesium ribbon
- 50 cm3 of 2.00 mol / dm3 hydrochloric acid
- a slightly higher temperature than the first experiment
Suggest why the volume collected is less than the expected volume.
Explain why it is not necessary to use a measuring cylinder in this experiment.
Mg (s) + 2H+ (aq) → Mg2+ (aq) + H2 (g)
(3)
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