Question

Suggest a way to determine the Λ°_m value of water.

Answer 1

Λ^∘_m value of water.

Consider the following chemical equations,

(i) H₂O(I) → H⁺(aq) + OH⁻(aq)

(ii) HCl(aq) → H⁺(aq) + Cl⁻(aq)

(iii) NaOH(aq) → Na⁺(aq) + OH⁻(aq)

(iv) NaCl(aq) → Na⁺(aq) + Cl⁻(aq)

Combining the four equations and using Kohlrausch's law, we get,

Λ^∘_{m(H\(_2\)O)} = Λ^∘_m(HCl) + Λ^∘_m(NaOH) − Λ^∘_m(NaCl)

Hence, if we know the values of Λ^∘_m for HCl, NaOH and NaCl, we can calculate the value of Λ^∘_m for water.

Answer 2

We know that water is a weak electrolyte. Its molar conductivity at infinite dilution i.e., Λ°_m can be determined in terms of Λ°_m, for strong electrolytes. 

This is in accordance with Kohlrausch's law.