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Chemistry · Ch 3 — Ionic Equilibria

Arrhenius theory of acids and bases

3.3.1

Arrhenius theory of acids and bases

According to this theory acids and bases are defined as follows :

Acid : Acid is a substance which contains hydrogen and gives rise to H+\mathrm{H^{+}} ions in aqueous solution. For example :

HCl(aq)→waterH+(aq)+Cl−(aq)\mathrm{HCl(aq)} \xrightarrow{\text{water}} \mathrm{H^{+}(aq)} + \mathrm{Cl^{-}(aq)}

CH3COOH(aq)⇌waterCH3COO−(aq)+H+(aq)\mathrm{CH_3COOH(aq)} \overset{\text{water}}{\rightleftharpoons} \mathrm{CH_3COO^{-}(aq)} + \mathrm{H^{+}(aq)}

Arrhenius described H+\mathrm{H^{+}} ions in water as bare ions; they hydrate in aqueous solutions and thus are represented as hydronium ions, H3O+\mathrm{H_3O^{+}}. We herewith conveniently represent them as H+\mathrm{H^{+}}.

Note

Do you know?

Hydrochloric acid, HCl present in the gastric juice is secreted by our stomach and is essential for digestion of food.

Base : Base is a substance that contains OH group and produces hydroxide ions (OH−\mathrm{OH^{-}}) in aqueous solution. For example,

NaOH(aq)→Na+(aq)+OH−(aq)\mathrm{NaOH(aq)} \rightarrow \mathrm{Na^{+}(aq)} + \mathrm{OH^{-}(aq)}

NH4OH(aq)⇌NH4+(aq)+OH−(aq)\mathrm{NH_4OH(aq)} \rightleftharpoons \mathrm{NH_4^{+}(aq)} + \mathrm{OH^{-}(aq)} …

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