JEE Main & Advanced Chemistry Equilibrium / साम्यावस्था Isohydric Solution

If the concentration of the common ions in the solution of two electrolytes, for example \[{{H}^{+}}\] ion concentration in \[HCl\] and \[HN{{O}_{3}}\] or \[O{{H}^{-}}\] ion concentration in \[Ca{{(OH)}_{2}}\] and \[Ba{{(OH)}_{2}}\] is same, then on mixing them there is no change in the degree of dissociation of either of the electrolytes. Such solutions are called isohydric solutions.

Consider two isohydric solutions of acids \[H{{A}_{1}}\] and\[H{{A}_{2}}\]. Let \[{{V}_{1}}\] and \[{{V}_{2}}\] be their dilutions and \[{{\alpha }_{1}}\] and \[{{\alpha }_{2}}\] be their degree of dissociation at the respective dilution. Then,

\[\frac{{{\alpha }_{1}}}{{{V}_{1}}}=\frac{{{\alpha }_{2}}}{{{V}_{2}}}\]

Above equation is useful for calculating the relative dilution of two acids at which they would be isohydric.