JEE Advanced2006ChemistryElectrochemistryActual
Paragraph: Tollen's reagent is used for the detection of aldehyde when a solution of AgNO ₃ is added to glucose with NH ₄ OH then gluconic acid is formed array rr Ag ⁺+e⁻ Ag & E_ red ^ =0.8 ~V C ₆ H ₁₂ O ₆+ H ₂ O Gluconic acid ( C ₆ H ₁₂ O ₇ )+2 H ⁺+2 e⁻ ; & -E_ red ^ =-0.05 ~V Ag ( NH ₃ )₂⁺+e⁻ Ag (s)+2 NH ₃ ; & E_ red ^ =0.337 ~V array [Use 2.303 R T F =0.0592 and F R T =38.92 at 298 ~K ] Question: When ammonia is a
Options
- AE_ oxd will increase by a factor of 0.65 from E_ oxd ^
- BE_ oxd will decrease by a factor of 0.65 from E_ oxd ^
- CE_ red will increase by a factor of 0.65 from E_ red ^
- DE_ red will decrease by a factor of 0.65 from E_ red ^
Correct answer
C. E_ red will increase by a factor of 0.65 from E_ red ^
Step-by-step solution
On increasing concentration of NH ₃ , the concentration of H ⁺ ion decreases, therefore aligned E_ red & =E_ red ^ - 0.0592 n ₁₀ [ H ⁺ ]^2 & =0- 0.0592 2 2 ₁₀ 10⁻¹¹ ( pH =11 ; [ H ⁺ ]=10⁻¹¹ M ) & =-0.0592 11=0.6512 ~V =0.65 ~V aligned E_ red increased by a factor of 0.65 from E_ red ^ .