Experiment: The effects of a catalyst on the rate of a reaction

Aim: To investigate the effects of a catalyst on a reaction using sulphuric acid and copper as a catalyst

Materials: granulated zinc, copper turnings, test tubes, dilute sulphuric acid, copper (II) sulphate solution

Methods

1. Place a few pieces of granulated zinc into a test tube
2. Cover the zinc with a 1 cm depth of dilute sulphuric acid
3. Note the rate at which the hydrogen gas bubbles are formed on the zinc
4. Add a few copper pieces so that they are in contact with the zinc
5. Notice the rate at wich the hydrogen gas evolved changes
6. Repeate the experiment with fresh acid and zin
7. Add 1 of copper (II) sulphate solution
8. Note the change in the rate of reaction and the colour of the copper sulphate
9. Pour away the acid and examine the granulated zinc

Results/Observations

• Copper acts as a catalyst and speeds up the rate of reaction between the granulated zinc and sulphuric acid
• This is evidenced by an increase in the rate at which the hydrogen bubbles are produced when the copper touches the zinc granules
• When copper sulphate is used as a catalyst the reaction between Zinc and sulphuric is even faster
• The zinc displaces copper from the copper sulphate and the surface of the zinc turns black
• The copper sulphate solution loses its blue colour to become almost colourless
• The orange colour of copper can also be observed

Conclusion

• Copper acts as a “catalyst” in the reaction and speeds up the reaction between sulphuric acid and zinc

NB Technically speaking the copper sulphate is not a catalyst as it is changed by the reaction process

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