QJEEM21Ch2e1b: JEE Main 2021 Chemistry - Class 12 JEEM21Ch2e1b Solution: Consider the following cell reaction : C d ( s ) + H g 2 S O 4…

Question

Verified Solution • 2025–26 Session moderate

Consider the following cell reaction :

C d_{(s)} + H g_{2} S O_{4 (s)} + \frac{9}{5} H_{2} O_{(l)}

⇌

C d S O_{4} . \frac{9}{5} H_{2} O_{(s)} + 2 H g_{(l)}

The value of

E_{c e l l}^{0}

is 4.315 V at 25

^{\circ}

C. If

Δ

H

^{\circ}

=

-

825.2 kJ mol^{$-$ 1}, the standard entropy change

Δ

S

^{\circ}

in J K^{$-$ 1} is ___________. (Nearest integer) [Given : Faraday constant = 96487 C mol^{$-$ 1}]

Accepted Answer

Δ G^{\circ} = - n F E^{\circ} = Δ H^{\circ} - T Δ S^{\circ}

∴

Δ

S

^{\circ}

= \frac{Δ H^{\circ} + n F E^{\circ}}{T}

= \frac{(- 825.2 \times 10^{3}) + (2 \times 96487 \times 4.315)}{298}

= \frac{- 825.2 \times 10^{3} + 832.682 \times 10^{3}}{298}

= \frac{7.483 \times 10^{3}}{298} = 25.11

JK^{$-$ 1} mol^{$-$ 1}

∴

Nearest integer answer is 25.

Step-by-Step Verified Solution