Principles of Catalysis

A catalyst is a substance that speeds up a chemical reaction but remains chemically unchanged at the end of the reaction.
Catalysts function by offering an alternative reaction pathway with a lower activation energy.
The reduction in activation energy means a higher proportion of the reactant particles colliding will have enough energy to react, therefore increasing the reaction rate.
Enzymes are biological catalysts that speed up reactions in living organisms.

Types of Catalysis

Homogeneous Catalysis: In this type of catalysis, the catalyst and the reactants are in the same phase, often all in the solution phase.
Heterogeneous Catalysis: The catalyst and the reactants are in different phases, typically solid catalysts used with gas or liquid reactants.
An example of heterogeneous catalysis is the Haber process where iron acts as a catalyst in the production of ammonia from nitrogen and hydrogen.

Catalysts play a vital role in various industrial chemical reactions.
They help speed up the rate of reaction and often enable reactions to proceed at lower temperatures, saving energy and resources, which is economically and environmentally beneficial.
In industry, the most widely used catalysts include metals such as platinum, nickel, or iron and non-metals like silica and alumina.

Enzymes are very specific biological catalysts often made from proteins.
Each type of enzyme can catalyse only one particular reaction or type of reaction because their activity depends on the shape of their active site.
Substrate molecules bind to the enzymes at their active sites forming an enzyme-substrate complex which later breaks down to give the enzyme and the products.
Various factors including temperature, pH, and enzyme and substrate concentrations can affect the rate of enzyme-catalysed reactions.
Enzyme inhibitors, competitive and non-competitive, can slow down or stop enzyme activity.