KEAM 2014 Physics and Chemistry Paper

Half cell reaction is
Cu2++2e−⟶Cu;n=2
From Nernst equation,
E=E∘−‌

2.303RT

nF

‌log‌

1

[Cu2+]

E1=E∘+‌

0.06

2

‌log[Cu2+]
Let the initial concentration of Cu2+ be 1 .
Further, the [Cu2+] solution is dilued to 100 times.
∴‌‌

M1V1

Initial

=

M2V2

After‌dilution

1×1=M2×100
M2=‌

1

100

=0.01
∴‌‌E2=E∘+‌

0.059

2

‌log[0.01]
=E∘+‌

0.059

2

(−2)
=E1−0.059V=E1−59mV
Thus, the potential decreases by 59(≈60)mV.