Question

Identify the correct decreasing order of thermodynamic stability of complexes from following.

• A. \([Co(NH_3)_6]^{3+} > [Ag(CN)_2]^{-} > [Cu(CN)_4]^{2-}\)
• B. \([Co(NH_3)_6]^{3+} > [Cu(CN)_4]^{2-} > [Ag(CN)_2]^{-}\)
• C. \([Cu(CN)_4]^{2-} > [Ag(CN)_2]^{-} > [Co(NH_3)_6]^{3+}\)
• D. \([Ag(CN)_2]^{-} > [Cu(CN)_4]^{2-} > [Co(NH_3)_6]^{3+}\)

Hint:

Compare the overall stability constants of the three complex ions.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept
Thermodynamic stability of a complex is measured by its stability constant. The larger the constant, the more stable the complex.

Step 2: Data
Approximate stability constants: \( [Co(NH_3)_6]^{3+} \) about \( 10^{35} \), \( [Cu(CN)_4]^{2-} \) about \( 10^{27} \), \( [Ag(CN)_2]^{-} \) about \( 10^{21} \).

Step 3: Order
\( [Co(NH_3)_6]^{3+} > [Cu(CN)_4]^{2-} > [Ag(CN)_2]^{-} \).

Step 4: Compare the options
This is option (B).

Final Answer:
The order is [Co(NH3)6]3+ > [Cu(CN)4]2- > [Ag(CN)2]-. \[ \boxed{\text{(B) }[Co(NH_3)_6]^{3+} > [Cu(CN)_4]^{2-} > [Ag(CN)_2]^{-}} \]