Ammonia forms the complex ion [Cu(NH3)4]2+ with copper ions in the alkaline solutions but not in acidic solutions. What is the reason for it?

Question

Ammonia forms the complex ion [Cu(NH3)4]2+ with copper ions in the alkaline solutions but not in acidic solutions. What is the reason for it? (A) In acidic solutions hydration protects copper ions (B) In acidic solutions protons coordinate with ammonia molecules forming NH4+ ions and NH3 molecules are not available (C) In alkaline solutions insoluble Cu(OH)2 is precipitated which is soluble in excess of any alkali (D) Copper hydroxide is an amphoteric substance

Tardigrade Admin · Accepted Answer

The pair of electron present with nitrogen will not be available to be donated as H+ will consume that one.

Q. Ammonia forms the complex ion $[C u (N H_{3})_{4}]^{2 +}$ with copper ions in the alkaline solutions but not in acidic solutions. What is the reason for it?

In acidic solutions hydration protects copper ions

In acidic solutions protons coordinate with ammonia molecules forming $N H_{4}^{+}$ ions and $N H_{3}$ molecules are not available

In alkaline solutions insoluble $C u (O H)_{2}$ is precipitated which is soluble in excess of any alkali

Copper hydroxide is an amphoteric substance

The pair of electron present with nitrogen will not be available to be donated as $H^{+}$ will consume that one.

Q. Ammonia forms the complex ion [Cu(NH3​)4​]2+ with copper ions in the alkaline solutions but not in acidic solutions. What is the reason for it?