What type of reaction involves the combination of two reactants to form a single product?

The reaction that involves the combination of two reactants to form a single product is known as a synthesis reaction. In a synthesis reaction, elements or simpler compounds unite to create a more complex compound. This type of reaction can be represented generally by the formula:

A + B → AB

Here, A and B are the reactants, and AB is the single product formed from them. Synthesis reactions are fundamental in chemistry because they are involved in the creation of many essential compounds, including those found in living organisms.

In contrast, decomposition reactions involve the breakdown of a single compound into two or more products. Single replacement and double replacement reactions involve the exchange of components between reactants rather than their combination to form a new compound. Thus, synthesis reactions specifically highlight the formation of a single product from multiple reactants, which clearly defines their unique nature in chemical processes.