Which of the following double salt does not exist? — d and f Block Elements Chemistry Question

💡 Solution & Explanation

Step 1: Tutton's salts are a class of double sulfates with the general formula M2_I M_II (SO4)2 . 6H2O, where M_I is a monovalent cation (like NH4+) and M_II is a divalent transition metal cation (like Fe2+, Zn2+, Ni2+). Step 2: These salts typically crystallize in a highly stable monoclinic lattice. Step 3: While Fe, Zn, and Ni form stable Tutton's salts, copper(II) forms a highly distorted coordination geometry due to the Jahn-Teller effect, which prevents the formation of a stable (NH4)2SO4 . CuSO4 . 6H2O double salt under standard conditions. Thus, option (a) is the correct answer.