Chemistry
Answer
Positive catalyst : When a catalyst increases the rate of a chemical reaction, it is known as a positive catalyst.
Example — Finely divided iron is used as a positive catalyst in the manufacture of ammonia from hydrogen and nitrogen.
Negative catalyst : When a substance decreases the rate of a chemical reaction, it is known as a negative catalyst or inhibitor.
Example — Phosphoric acid acts as a negative catalyst to decrease the rate of decomposition of hydrogen peroxide.
Related Questions
Illustrate the following characteristics of a chemical reaction by giving a suitable example of each:
(a) evolution of a gas
(b) change of colour
(c) change of state
What do you observe when dilute sulphuric acid is added to granulated zinc?
What do you observe when a few pieces of iron are dropped in a blue solution of copper sulphate?