Metathesis reactions are the Reactions in which two compounds react to form two new compounds, with no changes in oxidation number. e.g Reactions in which the ions of two compounds exchange ions.
The driving force for metathesis reactions is the removal of ions from solution
What are the ways in which ions can be removed from solution and thus drive a metathesis reaction?
- Certain ions can associate to form an insoluble precipitate (as with the formation of AgCl(s) bt mixing AgNO3 and NaCl(aq))
- Certain ions can chemically combine to form a neutral molecular compound (resulting in either a non-electrolyte, or a weak electrolyte)
Acid/base neutralization reactions that produce water from H+ and OH- ions are also an example of this.
- Being a non-electrolyte (or weak electrolyte) the formation of the molecular compound from the constituent ions is essentially an irreversible process
- Certain ions can chemically combine to form a gas, and the gas physically escapes from the solution.