According to Wikipedia:

A salt is an ionic compound that can be formed by the neutralization reaction of an acid and a base.

Are all ionic compounds salts? Are all salts ionic compounds?


Interestingly, IUPAC states that a "salt" is "a chemical compound consisting of an assembly of cations and anions". Under this definition, all ionic compounds are salts, and all salts are ionic compounds.

Therefore, something like sodium hydroxide ($\ce{Na+OH-}$, definitely an ionic compound) could actually be correctly called a salt. This clashes with the commonly taught high-school level definition of a salt ("the product of an acid-base reaction"), unless you consider very general definitions of acids and bases such as the Usanovich definition, whereby sodium metal $\ce{Na^0}$ is an electron donor (and therefore a base) and water is an electron acceptor (and therefore an acid).

That said, the high-school definition is too simplistic. It is common for compounds to be an acid, a base and a salt all at the same time; consider for example sodium bicarbonate ($\ce{Na+HCO3-}$). It is made of cations and anions, and therefore is definitely a salt. Furthermore, it can act as both a Brønsted–Lowry acid ($\ce{NaHCO3 + OH- -> H2O + Na+ + CO3^2-}$) and as a Brønsted–Lowry base ($\ce{NaHCO3 + H+ -> Na+ + H2CO3}$). Another amusing example is hydrazinium sulfate, a salt, acid and base, where both the cation and anion are also both acids and bases!

  • 4
    $\begingroup$ Sodium hydroxide is a potential acid-base product in ammonia solvent, produced from water (acid) and sodium amide (base). Thus the concept of a salt as an acid-base reaction product is a case of "it depends". $\endgroup$ Nov 26 '17 at 10:22
  • 1
    $\begingroup$ I think the better way to produce sodium hydroxide in an acid-base reaction would be to generate sodium oxide and then neutralise that with the acid water. That way, you don’t introduce any additional contaminants. $\endgroup$
    – Jan
    Nov 26 '17 at 14:47

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.