A single replacement reaction is a type of chemical reaction where one element replaces another element in a compound. This occurs when a more reactive element displaces a less reactive one. For example, if zinc is added to a solution of copper(II) sulfate, the zinc will replace the copper, resulting in zinc sulfate and copper metal. These reactions can be represented by the general formula: A + BC → AC + B, where A is the free element and BC is the compound. Single replacement reactions are common in various applications, including metallurgy and battery technology, where reactivity plays a crucial role.