PH Scale and Chemical Reactions - Essay Example

A chemical reaction is a term used to define the process in which two or more substances combine to form a product that is different from the elements it has constituted from or the breakdown of a compound into its elements.

In other words, any process which involves the sharing or transfer of electrons is a chemical reaction. A chemical reaction takes place when the reactants possess sufficient energy known as the activation energy of the reaction. Depending on the reactants involved and the conditions present, the reaction can be exothermic or endothermic. Chemical reactions involving reactive elements mostly go to completion while in some cases an equilibrium condition is achieved in which the products and reactants are present in equal proportions.

A chemical reaction results in a change in the chemical composition of the substances taking part in the reaction which is sometimes also coupled with a physical change. For example, the reaction between hydrogen and water is initiated by a spark that provides the activation energy for the reaction. The two gases combine chemically to form a new product, water that is different in physical as well as chemical properties from its constituent elements.