Question

# (a) define a base. (b) Explain, all alkalis are bases but all bases are not alkalis.

Open in App
Solution

## (a) Base is a compound that contains displaceable oxide (${\mathrm{O}}^{2-}$) or hydroxide (${\mathrm{OH}}^{-}$) ion or ions. A base reacts with ${\mathrm{H}}^{+}$ or ${\mathrm{H}}_{3}{\mathrm{O}}^{+}$ions (hydronium) present in an acid to produce a salt and water. Examples include NaOH and CuO. $\mathrm{NaOH}+\mathrm{HCl}\stackrel{}{\to }\mathrm{NaCl}+{\mathrm{H}}_{2}\mathrm{O}\phantom{\rule{0ex}{0ex}}\mathrm{Base}\mathrm{Acid}\mathrm{Salt}\mathrm{Water}$ (b) An alkali is a basic hydroxide that is soluble in water; it produces hydroxyl (${\mathrm{OH}}^{-}$) ions as the only negatively charged ions. Sodium hydroxide and calcium hydroxide are water-soluble bases; thus, they are alkalis. But all bases are not alkalis, as many bases do not dissolve in water.​ Bases like ferric hydroxide and cupric hydroxide are not soluble in water; hence, they are not alkalis. Thus, we can say that all alkalis are bases, but all bases are not alkalis.

Suggest Corrections
3