Q21 / 90 · JEE Main 2021 (26 Aug Shift 2) · Chemistry

For the galvanic cell,

Zn(s)+Cu2+(0.02M)→Zn2+(0.04M)+Cu(s)

Ecell =…×10-2 V (Nearest integer)

Use:E0Cu/Cu2+=-0.34 V,EZn/Zn2+=+0.76 V,2.303RTF=0.059 V

Correct answer: 109

Solution

Cell reaction

Cu2+(aq)+Zn⇌Cu(s)+Zn2+(aq)

0.02M                               0.04M

Ecell0=ECu2+∣Cu0-EZn2+∣Zn0

=0.34-(-0.75)=1.1 V

Ecell=Ecell0-0.0592logZn2+Cu2+

=1.1-0.0592log0.040.02

=1.1-0.03log2=1.1-0.03×0.30

=1.0915=1.09 V=109×10-2 V

Hence, the correct answer is 109.

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