Question #44742

The complex salt \ce{K2[Ni(EDTA)]} is dissolved in a large excess of an aqueous \ce{HCl} solution at $298 \text{ K}$ ($\text{pH} = 1.5$). Under these highly acidic conditions, the hexadentate EDTA ligand changes its denticity, and the complex exists exclusively as the protonated monoanion \ce{[Ni(HEDTA)]^-}. The protons required for this transformation are abstracted directly from the \ce{HCl} solution.

The apparent limiting molar conductivity of the salt in this medium is defined as: $\Lambda_{m, app}^\circ = \lim_{c \to 0} \frac{\kappa_{solution} - \kappa_{HCl}}{c}$ where $c$ is the molar concentration of the added salt.

Given the limiting ionic molar conductivities ($\lambda^\circ$) at $298 \text{ K}$ in $\text{S cm}^2 \text{ mol}^{-1}$: $\lambda^\circ(\ce{K^+}) = 73.5$ $\lambda^\circ(\ce{H^+}) = 349.6$ $\lambda^\circ(\ce{[Ni(EDTA)]^{2-}}) = 95.0$ $\lambda^\circ(\ce{[Ni(HEDTA)]^-}) = 45.0$

Calculate $\Lambda_{m, app}^\circ$ for \ce{K2[Ni(EDTA)]} in this medium.