Analytical Chemistry Question 184

Question: In the separation of $ C{u^{2+}} $ and $ C{d^{2+}} $ in 2nd group qualitative analysis of cations, tetrammine copper (II) sulphate and tetrammine cadmium (II) sulphate react with KCN to form the corresponding cyano complexes. Which one of the following pairs of the complexes and their relative stability enable the separation of $ C{u^{2+}} $ and $ C{d^{2+-}} $

Options:

A) $ K_3[ Cu{{( CN )}_4} ] $ more stable and $ K_2[Cd{{(CN)}_4}] $ less stable

B) $ K_2[ Cu{{( CN )}_4} ] $ less stable and $ K_2[Cd{{(CN)}_4}] $ more stable

C) $ K_2[ Cu{{( CN )}_4} ] $ more stable and $ K_2[Cd{{(CN)}_4}] $ less stable

D) $ K_3[ Cu{{( CN )}_4} ] $ less stable and $ K_2[Cd{{(CN)}_4}] $ more stable

Show Answer

Answer:

Correct Answer: A

Solution:

[a] $ K_3[Cu{{(CN)}_4}] $ is more stable whereas $ K_2[Cd{{(CN)}_4}] $ is less stable.