Question

$ Ag^+ \, + NH_3 \rightleftharpoons [ Ag ( NH_3 ) ]^+ ; K_1 = 3.5 \times 10^{ - 3 } $
$ [ Ag ( NH_3 )]^+ \, + NH_3 \rightleftharpoons [ Ag (NH_3 )_2 ]^+ ; K_2 = 1.7 \times 10^{ - 3 } $
then the formation constant of $ [ Ag (NH_3)_2]^+ $ is...

• A. $6.08 \times 10^{ - 6 } $
• B. $6.08 \times 10^6 $
• C. $6.08 \times 10^{ - 9 } $
• D. $5.95 \times 10^{ - 6 } $

Answer 1

Answer: (D)

$Ag ^{+}+ NH _{3} \rightleftharpoons\left[ Ag \left( NH _{3}\right)^{+}\right] \,\,K_{1}=3.5 \times 10^{-3}$
$\frac{\left[ Ag \left( NH _{3}\right)^{+}\right]+ NH _{3} \rightleftharpoons\left[ Ag \left( NH _{3}\right)_{2}^{+}\right] K_{2}=1.7 \times 10^{-3}}{\text { Adding : } Ag ^{+}+2 NH _{3} \rightleftharpoons\left[ Ag \left( NH _{3}\right)_{2}^{+}\right]}$
$K=K_{1} \times K_{2}=5.95 \times 10^{-6}$