Q.

At 298 K, the standard reduction potential for the Cu2+/Cu electrode is 0.34 V.

Given: KspCu(OH)2=1×10-20

Take 2.303RTF=0.059 V

The reduction potential at pH = 14 for the above couple is (-)x×10-2V. The value of x  is __________ .        [2023]


Ans.

(25)

pH=14pOH=0

[OH-]=1

KspCu(OH)2=[Cu2+][OH-]2=1×10-20

                             [Cu2+]=10-20

ECu2+|Cu=ECu2+|Cu0-0.0592log1[Cu2+]

=0.34-0.0592log1020

= -0.25

=-25×10-2 V