In: Chemistry
Calculate the Kf of Ag(NH3)2 + from
Ag+(aq) + e- ⇋ Ag(s) E0= 0.81 V
Ag(NH3)2+(aq) + e- ⇋ Ag(s) + 2NH3(aq) E0= 0.37 V
Let us write the reaction given :
1. Ag+(aq) + e- ⇋ Ag(s) E0= 0.81 V
2. Ag(NH3)2+(aq) + e- ⇋ Ag(s) + 2NH3(aq) E0= 0.37 V
To get Kf of Ag(NH3)2 we need to re arrange the above equation
3. Ag +(aq) + e- ⇋ Ag(s) E0= 0.81 V
4. Ag(s) + 2NH3(aq) ⇋ Ag(NH3)2+(aq) + e- E0= - 0.37 V
Adding equation (3) and equation (4)
Ag +(aq) + 2NH3(aq) ⇋ Ag(NH3)2+(aq) Eo = 0.81 -0.37 = 0.44 V
We will use the nernst equation,
Now Kf is calculate at equilibrium and at equilibrium E=0,
The number of transfer of electro is 1 ( 1 e-) , n=1
Eo = 0.44 V
Substituting all the values in nernst equation
Kf= 2.786 *107
Hence, Kf for the above reaction is 2.786 *107