copper(ii) complex

In aqueous solutions, only free Cl-(aq) can react with Ag+(aq) ions to form AgCl precipitate.
Ag+(aq) + Cl-(aq) → AgCl(s)
On the other hand, when Cl- ions acts as ligands in stable complexes, no AgCl precipitate is formed when treated with AgNO3 solution. This is because the dissociation of stable complexes is negligible and thus the amount of free Cl-(aq) ions is negligible.

Na2[CuCl4]: In aqueous solution, each mol of Na2[CuCl4] gives 2 mol of Na+(aq) ions and 1 mol of [CuCl4]2-(aq) ions. There are no free Cl-(aq) ions.

[CuCl2(NH3)2]: In aqueous solution, the neutral complex gives no free Cl-(aq) ions.

[Cu(NH3)4]Cl2: In aqueous solution, each mol of [Cu(NH3)4]Cl2 gives 1 mol of [Cu(NH3)4]2+(aq) ions and 2 mol of free Cl-(aq) ions.

[CuCl(NH3)3]Cl: In aqueous solution, each mol of [CuCl(NH3)3]Cl gives 1 mol of [CuCl(NH3)3]+ and 1 mol of free Cl-(aq) ions.

Hence, [Cu(NH3)4]Cl2 will gives the largest amount of AgCl solid. This is because each mole of the compound gives the largest amount of free Cl-(aq) ions.
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