Question

Suggest a way to determine the \[\ce{\Lambda^{\circ}_m}\] value of water.

Answer 1

Water is a weak electrolyte. Its \[\ce{\Lambda^{\circ}_m}\] value can be determined with the help of Kohlrausch’s law.

\[\ce{\Lambda^{\circ}_m(HCl) = \Lambda^{\circ}_m(H+) + \Lambda^{\circ}_m(Cl^-)}\]    ...(i)

\[\ce{\Lambda^{\circ}_m(NaOH) = \Lambda^{\circ}_m(Na+) + \Lambda^{\circ}_m(OH^-)}\]    ...(ii)

\[\ce{\Lambda^{\circ}_m(NaCl) = \Lambda^{\circ}_m(Na+) + \Lambda^{\circ}_m(Cl^-)}\]    ...(iii)

Adding (i) and (ii) and subtracting (iii), we get,

\[\ce{\Lambda^{\circ}_m(H2O) = \Lambda^{\circ}_m(H+) + \Lambda^{\circ}_m(OH^-)}\]

= \[\ce{\Lambda^{\circ}_m(HCl) + \Lambda^{\circ}_m(NaOH) - \Lambda^{\circ}_m(NaCl)}\]