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Question
Suggest a way to determine the \[\ce{\Lambda^{\circ}_m}\] value of water.
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Solution
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,
\[\ce{\Lambda^{\circ}_m(H2O) = \Lambda^{\circ}_m(H+) + \Lambda^{\circ}_m(OH^-)}\]
= \[\ce{\Lambda^{\circ}_m(HCl) + \Lambda^{\circ}_m(NaOH) - \Lambda^{\circ}_m(NaCl)}\]
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