Activity Project: Effect of Surface Area on Rate of Reaction
Objective
To study how changing the surface area of a solid affects its rate of reaction with a liquid.
Materials Required
- Zinc granules and zinc powder (different particle sizes)
- Hydrochloric acid (dilute, ~1M)
- Measuring cylinder
- Conical flask
- Gas collection setup (water displacement or gas syringe)
- Stopwatch
- Thermometer
Procedure
- Measure equal mass (e.g., 1 g) of zinc in granular and powdered form separately.
- Fill the measuring cylinder with 50 mL of dilute hydrochloric acid and pour it into the conical flask.
- Start the stopwatch and add zinc granules to the acid, quickly attach the conical flask to the gas collection setup.
- Measure the volume of hydrogen gas evolved every 30 seconds.
- Continue until the reaction completes (no more gas evolves).
- Repeat the experiment using the same mass of zinc powder.
- Record volumes of hydrogen gas collected over time for both surface areas.
Observation Table
| Time (seconds) | Volume of H₂ gas (mL) – Zinc Granules | Volume of H₂ gas (mL) – Zinc Powder |
|---|---|---|
| 30 | 12 | 22 |
| 60 | 20 | 38 |
| 90 | 28 | 55 |
| 120 | 35 | 67 |
| 150 | 40 | 75 |
| End | 42 | 78 |
Result
The reaction rate increases with increasing surface area. Zinc powder with larger surface area shows faster reaction with hydrochloric acid compared to zinc granules.
Precautions
- Use the same mass of zinc for both forms for proper comparison.
- Ensure airtight gas collection setup for accurate volume measurement.
- Carry out the experiment at constant temperature.
- Handle hydrochloric acid with care; use gloves and goggles.