Factors Affecting - Presence of Catalyst

  1. A catalyst is a substance which can change the rate of reaction. 
  2. There are 2 types of catalyst: 
    1. Positive catalyst – Increase the rate of reaction. 
    2. Negative catalyst – Reduce the rate of reaction.
Experiment 1

Set 1: Zinc + Hydrochloric Acid
Set 2: Zinc + Hydrochloric Acid + Copper Sulphate (Catalyst)

Chemical Reaction:
Zn + 2HCl → ZnCl2 + H2

Result:

Copper(II) sulphate acts as a catalyst to increase the rate of reaction between zinc and hydrochloric acid


Conclusion
The presence of catalyst increases the rate of reaction.

Experiment 2
Set 1: Decomposition of Hydrogen Peroxide
Set 2: Decomposition of Hydrogen Peroxide + Manganese(IV) Oxide (Catalyst)

Chemical Reaction: 
2H2O2 → 2H2O + O2

Result:

Manganese(IV) oxide acts as a catalyst to increase the rate of reaction between zinc and hydrochloric acid


Conclusion:
The presence of catalyst increases the rate of reaction

Note:
In SPM, you need to remember the catalyst used in both the chemical reaction above.