Surface Chemistry - Auto catalysis, Negative Catalysis | 12th Chemistry : UNIT 10 : Surface Chemistry

Chapter: 12th Chemistry : UNIT 10 : Surface Chemistry

Auto catalysis, Negative Catalysis

In certain reactions one of the products formed acts as a catalyst to the reaction. Initially the rate of reaction will be very slow but with the increase in time the rate of reaction increases.

Auto catalysis

In certain reactions one of the products formed acts as a catalyst to the reaction. Initially the rate of reaction will be very slow but with the increase in time the rate of reaction increases.

Auto catalysis is observed in the following reactions.

CH₃COOC₂H₅+H₂O → CH₃COOH+C₂H₅OH

Acetic acid acts as the autocatalyst

2AsH₃ → 2As+3H₂

Arsenic acts as an autocatalyst

Negative Catalysis

In certain reactions, presence of certain substances, decreases the rate of the reaction.

Ethanol is a negative catalyst for the following reaction.

(i) 4CHCl ₃ +3O ₂ → 4COCl ₂ +2H₂O+2Cl₂

Ethanol decreases the rate of the reaction

(ii) 2H₂O₂ → 2H₂O+O₂

In the decomposition of hydrogen peroxide, dilute acid or glycerol acts as a negative catalyst.

Tags : Surface Chemistry , 12th Chemistry : UNIT 10 : Surface Chemistry

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12th Chemistry : UNIT 10 : Surface Chemistry : Auto catalysis, Negative Catalysis | Surface Chemistry