A cell Ag ∣ AgCl ( s ) ∣ KCl ( 0.1 M ) ∣ ∣ KCl ( sat ) ∣ Hg 2 Cl 2 ( s ) ∣ Hg ( l ) has an EMF of 0.053 V at 298 K . If the temperature is raised to 308 K , and the entropy change for the Calomel

Question

A cell Ag ∣ AgCl ( s ) ∣ KCl ( 0.1 M ) ∣ ∣ KCl ( sat ) ∣ Hg 2 ​ Cl 2 ​ ( s ) ∣ Hg ( l ) has an EMF of 0.053 V at 298 K . If the temperature is raised to 308 K , and the entropy change for the Calomel half-reaction is much larger than for the SilverSilver Chloride half-reaction, the EMF will:

TestHub · Accepted Answer

The cell reaction involves chloride ion transfer from 0.1 M to saturated KCl. Since saturated solutions have lower entropy than dilute ones, the overall entropy change ( $Δ S_{ce ll}$ ) is negative. Given that $(\frac{\partial E}{\partial T})_{P} = \frac{Δ S _{ce ll}}{n F}$ , a negative $Δ S_{ce ll}$ implies a negative temperature coefficient ( $\frac{\partial E}{\partial T} < 0$ ). Therefore, increasing the temperature will decrease the EMF.

Final Answer: Option (B)

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JEE Advanced (2028)