Question

From the stability constants (hypothetical values) given below, predict which one is the strongest ligand?

• A. $C{u}^{+2}+4N{H}_3\rightleftharpoons \left[Cu\right(N{H}_3{)}_4{]}^{2+}K=4.5\times {10}^{11}$
• B. $C{u}^{+2}+4C{N}^{-}\rightleftharpoons \left[Cu\right(CN{)}_4{]}^{2-}K=2.0\times {10}^{27}$
• C. $C{u}^{+2}+2e{n}^{-}\rightleftharpoons \left[Cu\right(en{)}_2{]}^{2+}K=3.0\times {10}^{15}$
• D. $C{u}^{+2}+4H_{2}O-\rightleftharpoons \left[Cu\right(H_{2}O{)}_4{]}^{2+}K=9.5\times {10}^8$

Answer 1

The correct option is D $C{u}^{+2}+4H_{2}O-\rightleftharpoons \left[Cu\right(H_{2}O{)}_4{]}^{2+}K=9.5\times {10}^8$

Stability constant is a measure of strength of the interaction between the reagents that come together to form a complex. Greater the value of the stability constant, stronger is the ligand.