What are the two important classes of catalysts?

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To understand Catalysts, it is necessary to understand what Catalysis is.

Catalysis is the change in rate of a chemical reaction due to the participation of a substance called a catalyst.

In other words, a chemical reaction that might occur naturally is sped up or slowed down by the introduction of a new substance which is not directly involved with the reaction itself. Catalysts are not used up by the reaction, but they might be damaged or made useless for further participation in the reaction process.
The two main forms of Catalysis are Heterogeneous and Homogeneous.

A Heterogeneous catalyst operates separately from the reactants; it is not in the same Phase, or uniform state, as the chemicals it is affecting. These are important for chemical production on a mass scale; many chemicals that do not naturally occur in large quantities can be synthesized quickly this way. An example of Heterogeneous Catalysis is the Haber Process, which synthesizes Ammonia from Nitrogen and Hydrogen using Iron filings.

A Homogeneous catalyst operates with the reactants; it is in the same Phase, or Uniform state, as the chemicals it is affecting. These catalysts will be mixed with or placed on the reactants directly and then remain in the solution while the reaction occurs. An example of Homogeneous Catalysis is destruction of Ozone by CFCs, which bond with free Oxygen atoms, preventing the formation of new Ozone.

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What are two important classes of catalysts?

They are heterogenous catalysts and homogenous catalysts

Heterogenous catalysts -

The catalyst is in a different phase to the reaction phase. Ex: Fe in Haber process

 

Homogeneous catalysts -

THe catalyst is in the same phase of the reaction. Ex: chlorine (Cl2) in ozone disintegration reaction

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What are the two classes of catalyst?

Catalysts are any substance that affects chemical reaction; a catalyst can slow a reaction, or speed it up. The catalyst is not directly involved with the reaction itself, only serving to act on the speed; however, the catalyst can be rendered useless by the reaction, in which case it must be reintroduced each time the reaction occurs.

The two classes of Catalyst are Homogeneous and Heterogeneous.

A Homogeneous catalyst is a substance in the same phase, or state, as the reacting chemicals. If a gaseous reaction is occurring, a homogeneous catalyst will also be a gas. An example of this is alcohol dehydration; when changing ethanol to ethylene, sulfuric acid is used as a catalyst, but does not remain in the final substance.

A Heterogeneous catalyst is a substance not in the same phase as the reacting chemicals. If a gaseous reaction occurs, a heterogeneous catalyst can be a solid or a solid. An example of this is fluid catalytic cracking, which separates crude oil molecules; the crude oil is in a vaporous state, while the cracking catalyst is usually a powder, or solid state.

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