Q. Ammonia forms the complex ion $\left\lbrack Cu\left( {NH}_{3} \right)_{4} \right\rbrack^{2 +}$ 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 ${NH}_{4}^{+}$ ions and ${NH}_{3}$ 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
Explanation
(b)
The pair of electron present with nitrogen will not be available to be donated as $H^{+}$ will consume that one.
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.