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QJEEM23Ch1147: JEE Main 2023 Chemistry - Class 12 JEEM23Ch1147 Solution: The standard reduction potentials at for the following half…

The standard reduction potentials at 298 K298 \mathrm{~K} for the following half cells are given below:

NO3−+4H++3e−→NO(g)+2H2OEθ=0.97 V\mathrm{NO}_{3}^{-}+4 \mathrm{H}^{+}+3 \mathrm{e}^{-} \rightarrow \mathrm{NO}(\mathrm{g})+2 \mathrm{H}_{2} \mathrm{O} \quad \mathrm{E}^{\theta}=0.97 \mathrm{~V}

V2+(aq)+2e−→VEθ=−1.19 V\mathrm{V}^{2+}(\mathrm{aq})+2 \mathrm{e}^{-} \rightarrow \mathrm{V} \quad\quad\quad \mathrm{E}^{\theta}=-1.19 \mathrm{~V}

Fe3+(aq)+3e−→FeEθ=−0.04 V\mathrm{Fe}^{3+}(\mathrm{aq})+3 \mathrm{e}^{-} \rightarrow \mathrm{Fe} \quad\quad\quad \mathrm{E}^{\theta}=-0.04 \mathrm{~V}

Ag+(aq)+e−→Ag(s)Eθ=0.80 V\mathrm{Ag}^{+}(\mathrm{aq})+\mathrm{e}^{-} \rightarrow \mathrm{Ag}(\mathrm{s}) \quad\quad\quad \mathrm{E}^{\theta}=0.80 \mathrm{~V}

Au3+(aq)+3e−→Au(s)Eθ=1.40 V\mathrm{Au}^{3+}(\mathrm{aq})+3 \mathrm{e}^{-} \rightarrow \mathrm{Au}(\mathrm{s}) \quad\quad\quad \mathrm{E}^{\theta}=1.40 \mathrm{~V}

The number of metal(s) which will be oxidized by NO3−\mathrm{NO}_{3}^{-} in aqueous solution is __________.

Step-by-Step Verified Solution

To determine the metals that can be oxidized by NO3−NO_3^- , we need to find the metals that have a standard reduction potential (SRP) lower than 0.97 V (since NO3−NO_3^- has an SRP of 0.97 V).

From the given data, we can find the metals that satisfy this condition:

  1. V2+(aq)+2e−→VV^{2+} (\text{aq}) + 2e^- \rightarrow V , Eθ=−1.19 VE^\theta = -1.19 \, \text{V} (less than 0.97 V, hence can be oxidized)

  2. Fe3+(aq)+3e−→FeFe^{3+} (\text{aq}) + 3e^- \rightarrow Fe , Eθ=−0.04 VE^\theta = -0.04 \, \text{V} (less than 0.97 V, hence can be oxidized)

  3. Ag+(aq)+e−→Ag(s)Ag^+ (\text{aq}) + e^- \rightarrow Ag (\text{s}) , Eθ=0.80 VE^\theta = 0.80 \, \text{V} (less than 0.97 V, hence can be oxidized)

  4. Au3+(aq)+3e−→Au(s)Au^{3+} (\text{aq}) + 3e^- \rightarrow Au (\text{s}) , Eθ=1.40 VE^\theta = 1.40 \, \text{V} (greater than 0.97 V, hence cannot be oxidized)

Therefore, VV , FeFe , and AgAg are the metals that can be oxidized by NO3−NO_3^- .

The total number of such metals is 3.

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