Evidences of Arrhenius theory of electrolytic dissociation

Evidences of Arrhenius theory of electrolytic dissociation

1. The enthalpy of neutralisation of strong acid by strong base is a constant value and is equal to -57.32 kJ. gm.equiv ^-1. This aspect is well explained by adopting Arrhenius theory of electrolytic dissociation. Strong acids and strong bases are completely ionised in water and produce H⁺ and OH^- ions respectively along with the counter ions. The net reaction in the acid-base neutralisation is the formation of water from H⁺ and OH^- ions.

H⁺ + OH^-  -- -- - > H₂O,   DH_r^o = -57.32 kJ.mol ^-1

2.The colour of certain salts or their solution is due to the ions present. For example, copper sulphate is blue due to Cu²⁺ ions. Nickel salts are green due to Ni²⁺ ions. Metallic chromates are yellow due to CrO₄^2- ions.

3.Ostwalds dilution law, common ion effect and solubility product and other such concepts are based on Arrhenius theory.

4.Chemical reactions between electrolytes are almost ionic reactions. This is because these are essentially the reaction between oppositely charged ions. For example,

Ag⁺ + Cl^- --- -- > AgCl ¯

5.Electrolytic solutions conduct current due to the presence of ions which migrate in the presence of electric field.

6.Colligative properties depend on the number of particles present in the solution. Electrolytic solution has abnormal colligative properties. For example, 0.1 molal solution of NaCl has elevation of boiling point about twice that of 0.1 molal solution of non-electrolyte. The abnormal colligative properties of electrolytic solutions can be explained with theory of electrolytic dissociation.