Magnesium reacts with dilute hydrochloric acid to produce magnesium chloride and hydrogen gas - Edexcel - GCSE Chemistry - Question 5 - 2018 - Paper 1

The formula of a molecule of hydrogen is H₂.

The correct hazard symbol indicating that a substance is an irritant is symbol A.

To investigate how changing the concentration of hydrochloric acid affects the rate of reaction with magnesium ribbon, the student should follow these steps:

1. Measure the Volume of Acid: Use the measuring cylinder to measure a fixed volume of hydrochloric acid of known concentration.

2. Prepare the Magnesium Ribbon: Cut equal lengths of magnesium ribbon to ensure consistent surface area.

3. Add Magnesium to the Flask: Place the magnesium ribbon in the conical flask.

4. Collect Gas Using Gas Syringe: Connect the gas syringe to the conical flask, ensuring a tight seal, to collect hydrogen gas evolved during the reaction.

5. Start the Stopwatch: As soon as the hydrochloric acid is added to the flask, start the stopwatch to time the reaction.

6. Measure Volume of Hydrogen: Monitor the gas syringe and record the volume of hydrogen gas produced at regular time intervals.

7. Repeat with Different Concentrations: Repeat the experiment using different concentrations of hydrochloric acid, keeping all other variables constant, such as temperature and the length of magnesium ribbon.

8. Analyze Results: Compare the volume of hydrogen produced over the same period for different concentrations. A higher concentration should yield more hydrogen in a shorter time, demonstrating that increasing acid concentration increases the rate of reaction.