singlereplacement

Single replacement, also known as single displacement or substitution, is a chemical reaction in which one element is substituted for another element in a compound. This type of reaction typically involves a more reactive element displacing a less reactive element from its compound. The general form of a single replacement reaction is A + BC → AC + B or A + BC → BA + C, where A is an element and BC is a compound.

For single replacement reactions to occur, element A must be more reactive than element B in the compound BC. Reactivity is often determined by comparing the positions of the elements in the activity series. For metals, a more reactive metal will displace a less reactive metal from its salt solution. For example, zinc (Zn) is more reactive than copper (Cu), so zinc will displace copper from copper sulfate (CuSO4) solution: Zn + CuSO4 → ZnSO4 + Cu. Similarly, a more reactive nonmetal can displace a less reactive nonmetal from its compound. For instance, chlorine (Cl2) is more reactive than bromine (Br2), so chlorine can displace bromine from sodium bromide (NaBr) solution: Cl2 + 2NaBr → 2NaCl + Br2. Hydrogen can also be displaced from water or acids by reactive metals.

Single replacement reactions are important in various industrial processes, such as the extraction of metals from their ores and the production of certain chemicals. They are also observed in natural processes, like the weathering of rocks. Understanding the relative reactivity of elements is key to predicting whether a single replacement reaction will occur and what the products will be.