MHT CET202526 Apr 2025Evening ShiftChemistryElectrochemistryActual
What happens to the emf for the cell , ^ Zn _ ( s ) | Zn ⁺²(1 M ) | | Ag ⁺¹(1 M ) | Ag _ ( s ) if concentration of Ag ⁺¹ decreases to 0.1 M ?
Options
- Aincrease by 0.0592 V
- Bdecrease by 0.0592 V
- Cincrease by 0.0296 V
- Ddecrease by 0.0296 V
Correct answer
B. decrease by 0.0592 V
Step-by-step solution
The electrochemical cell is Zn _ ( s ) | Zn ²⁺(1 M ) | | Ag ^+(1 M ) | Ag _ ( s ) with the overall reaction Zn _ ( s ) + 2 Ag ^+_ ( aq ) Zn ²⁺_ ( aq ) + 2 Ag _ ( s ) Initial concentrations give Q₁ = 1 , so E₁ = E^ _ cell When [ Ag ^+] = 0.1 M , Q₂ = [ Zn ²⁺] [ Ag ^+]^2 = 100 The Nernst equation yields E₂ = E^ _ cell - 0.0592 2 100 = E^ _ cell - 0.0592 V The change in emf is E₂ - E₁ = -0.0592 V , indicating a decrease Answer: B