Question

Which of the following complexes formed by $Cu^{2 +}$ions is most stable?

• A. $Cu^{2 +} + 4NH_{3}$ $\lbrack Cu(NH_{3})_{4}\rbrack 2 + ,$log K = $11.6$
• B. $Cu^{2 +} + 4CN^{-}$ $\lbrack Cu(CN)_{4}\rbrack^{2 -},$ log K = $27.3$
• C. $Cu^{2 +} + 2en$ $\lbrack Cu(en)_{2}\rbrack^{2 +},$ log K = $15.4$
• D. $Cu^{2 +} + 4H_{2}O$ $\lbrack Cu(H_{2}O)_{4}\rbrack^{2 +}$, log K = $8.9$

Answer 1

Answer: (B)

Cu^{2 +} + 4CN^{-}$$\lbrack Cu(CN)_{4}\rbrack^{2 -}, log K = $27.3$

Answer 2

Higher the value of stability constant K, greater is the stability.