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Single Replacement Reactions

Single replacement reactions

Single replacement reactions, also known as single displacement reactions, occur when an element reacts with a compound and takes the place of another element in that compound. This type of reaction is represented by the general equation: A + BC → AC + B or A + BC → AB + C (depending on whether A is a metal or a non-metal).

Key points

  1. Reactivity series: The occurrence of single replacement reactions depends on the reactivity series of the elements involved. A more reactive element can replace a less reactive element from its compound.

  2. Energy considerations: Some single replacement reactions are exothermic, releasing energy in the form of heat or light, while others may require an input of energy to proceed.

Examples

A classic example is the reaction of iron with copper(II) sulfate, where iron replaces copper (Fe + CuSO4 → FeSO4 + Cu). Another example is the replacement of hydrogen in water by a metal, such as sodium (2Na + 2H2O → 2NaOH + H2).