The conductivity of a solution of complex with formula $\mathrm{CoCl}_{3}\left(\mathrm{NH}_{3}\right)_{4}$ corresponds to $1:1$ electrolyte, then the primary valency of central metal ion is ____

JEE Main · 2022 · 27 Jul 2022 · Shift 1 · Coordination Compounds

The conductivity of a solution of complex with formula

CoCl_{3} (NH_{3})_{4}

corresponds to

1 : 1

electrolyte, then the primary valency of central metal ion is ____

Answer: 3

Solution

A 1:1 electrolyte produces two ions in solution. The complex

CoCl_{3} (NH_{3})_{4}

must dissociate as

[Co (NH_{3})_{4} Cl_{2}] Cl

, giving one complex cation and one chloride anion. The primary valency equals the oxidation state of the central metal ion. Since two chlorides are in the coordination sphere and one is outside, cobalt must be in the +3 oxidation state to balance the three chloride ions. Therefore, the primary valency is 3.

JEE Main · 2022 · 27 Jul 2022 · Shift 1 · Integer answer

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