Question

Assertion :${\beta }_4$ for the $\left[Cu\right(N{H}_3{)}_4{]}^{2+}$ ion is $2.1\times {10}^{13}$, hence its instability constant is $4.76\times {10}^{-14}$. Reason: Instability constant or dissociation constant is reciprocal of the formation constant.

• A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
• B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
• C. Assertion is correct but Reason is incorrect
• D. Both Assertion and Reason are incorrect

Answer 1

The correct option is A Both Assertion and Reason are correct and Reason is the correct explanation for Assertion

Instability constant $=\frac{1}{{\beta }_4}=\frac{1}{2.1\times {10}^{13}}=4.76\times {10}^{-14}$.

$\left[Cu\right(N{H}_3{)}_4{]}^{2+}\to \left[Cu\right(N{H}_3{)}_3{]}^{2+}+N{H}_3$

Instability constant $=\frac{\left[Cu\right(N{H}_3{)}_3{]}^{2+}\left[N{H}_3\right]}{\left[Cu\right(N{H}_3{)}_4{]}^{2+}}$

$\left[Cu\right(N{H}_3{)}_3{]}^{2+}+N{H}_3\to \left[Cu\right(N{H}_3{)}_4{]}^{2+}$

Stability constant $={\beta }_4=\frac{\left[Cu\right(N{H}_3{)}_4{]}^{2+}}{\left[Cu\right(N{H}_3{)}_3{]}^{2+}\left[N{H}_3\right]}$