The type of chemical reaction where two or more reactants combine to form one product only is known as a combination reaction. In this reaction, the reactants can be elements or compounds, and they combine to form a single compound as the product.
For example, when hydrogen gas (H2) reacts with oxygen gas (O2), they combine to form water (H2O). The chemical equation for this reaction is:
2H2 + O2 → 2H2O
In this reaction, two molecules of hydrogen gas and one molecule of oxygen gas combine to form two molecules of water. This is a classic example of a combination reaction.
Combination reactions are often exothermic, meaning they release energy in the form of heat or light. These reactions are fundamental in chemistry and are used in various industrial processes, such as the synthesis of ammonia (NH3) from nitrogen (N2) and hydrogen (H2).