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JEE Advanced 2006
Exam
JEE Advanced
Year
2006
Subject
Chemistry
Chapter
Electrochemistry

JEE Advanced 2006 · Chemistry · Electrochemistry

Paragraph: Tollen's reagent is used for the detection of aldehyde...

Paragraph: Tollen's reagent is used for the detection of aldehyde when a solution of AgNO3\mathrm{AgNO}_3 is added to glucose with NH4OHthengluconicacidisformed\mathrm{NH}_4 \mathrm{OH} then gluconic acid is formed\begin{array}{rr}\mathrm{Ag}^{+}+e^{-} \rightarrow \mathrm{Ag} & E_{\text{red }^{\circ}=0.8 \mathrm{ V} \\ \mathrm{C}_6 \mathrm{H}_{12} \mathrm{O}_6+\mathrm{H}_2 \mathrm{O} \rightarrow \text{ Gluconic acid }\left(\mathrm{C}_6 \mathrm{H}_{12} \mathrm{O}_7\right)+2 \mathrm{H}^{+}+2 e^{-} ; & -E_{\mathrm{red}^{\circ}=-0.05 \mathrm{ V} \\ \mathrm{Ag}\left(\mathrm{NH}_3\right)_2^{+}+e^{-} \rightarrow \mathrm{Ag}(s)+2 \mathrm{NH}_3 ; & E_{\mathrm{red}^{\circ}=0.337 \mathrm{ V}\end{array}$[Use[Use2.303 \times \frac{R T}{F}=0.0592andand\frac{F}{R T}=38.92atat298 \mathrm{ K} ]Question: Ammonia is always added in this reaction. Which of the following must be incorrect?$

Options

  1. ANH3\mathrm{NH}_3 combines with Ag+\mathrm{Ag}^{+}to form a complex
  2. B\mathrm{Ag}(NH3)2+\left(\mathrm{NH}_3\right)_2^{+}is a stronger oxidising reagent than Ag+\mathrm{Ag}^{+}.
  3. CIn absence of NH3\mathrm{NH}_3 silver salt of gluconic acid is formed.
  4. DNH3\mathrm{NH}_3 has affected the standard reduction potential of glucose/gluconic acid electrode.

Correct answer

D. NH3\mathrm{NH}_3 has affected the standard reduction potential of glucose/gluconic acid electrode.

Step-by-step solution

Ammonia has no effect on the standard reduction potential.
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