A student investigates the reaction of different metals with dilute sulfuric acid using a polystyrene cup:
(i) The student notices that the temperature rises when a metal is added to the acid. What name is given to this type of reaction?
(ii) The metal lithium reacts with hydrochloric acid, HCl\text{HCl}HCl, to form lithium chloride, LiCl\text{LiCl}LiCl, and hydrogen, H2\text{H}_2H2. Write a balanced symbol equation for this reaction.
(iii) The experiment is repeated with magnesium and sulfuric acid. Write down the name of the salt produced in this reaction.
The student repeats the experiment with different metals. She repeats the experiment three times for each metal, measuring the temperature change in each experiment.
| Metal | Temperature change (∘C^{\circ}\text{C}∘C) | ||
|---|---|---|---|
| Test 1 | Test 2 | Test 3 | |
| Magnesium | 12.2 | 12.5 | 12.3 |
| Zinc | 6.8 | 3.2 | 7.0 |
| Iron | 4.1 | 4.3 | 4.2 |
(i) One of the student's results is anomalous. State the metal and the test number for this anomalous result.
(ii) Suggest a reason why this result could be anomalous.
(iii) Calculate the mean temperature change for magnesium. Give your answer to 1 decimal place.
(i) The student wants to improve her experiment to get more accurate results. Suggest an improvement to her experiment and give a reason for this improvement.
(ii) The student concludes that the more reactive the metal is, the higher the temperature rise. Describe further tests the student can do to confirm her conclusion.
Diagrammatically sketch or describe the reaction profile for the reaction between magnesium and sulfuric acid based on the template below:
Label on your description or drawing the:
- products
- energy change
- activation energy.