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NEET 2026
Exam
NEET
Year
2026
Subject
Chemistry
Chapter
Chapter

NEET 2026 · Chemistry · Chapter

For a galvanic cell operating at 298 K , the overall cell reaction...

For a galvanic cell operating at 298 K298\text{ K}, the overall cell reaction is given as:

2Al(s)+3Cu2+(0.001 M)→2Al3+(0.001 M)+3Cu(s)2\text{Al(s)} + 3\text{Cu}^{2+}(0.001\text{ M}) \rightarrow 2\text{Al}^{3+}(0.001\text{ M}) + 3\text{Cu(s)}

If the standard cell potential (Ecell∘E^\circ_{\text{cell}}) for this reaction is 2.00 V2.00\text{ V}, what is the operating electromotive force (emf) of the cell?
(Assume 2.303RTF=0.059 V\dfrac{2.303 RT}{F} = 0.059\text{ V} at 298 K298\text{ K})

Options

  1. A2.0295 V2.0295\text{ V}
  2. B1.9705 V1.9705\text{ V}
  3. C1.9115 V1.9115\text{ V}
  4. D2.00 V2.00\text{ V}

Correct answer

B. 1.9705 V1.9705\text{ V}

Step-by-step solution

The given cell reaction is:

2Al(s)+3Cu2+(0.001 M)→2Al3+(0.001 M)+3Cu(s)2\text{Al(s)} + 3\text{Cu}^{2+}(0.001\text{ M}) \rightarrow 2\text{Al}^{3+}(0.001\text{ M}) + 3\text{Cu(s)}

The number of electrons transferred in the balanced reaction is n=6n = 6.

The reaction quotient QQ is given by:

Q=[Al3+]2[Cu2+]3Q = \dfrac{[\text{Al}^{3+}]^2}{[\text{Cu}^{2+}]^3}

Substituting the given concentrations:

Q=(10−3)2(10−3)3=10−610−9=103Q = \dfrac{(10^{-3})^2}{(10^{-3})^3} = \dfrac{10^{-6}}{10^{-9}} = 10^3

Using the Nernst equation:

Ecell=Ecell∘−0.059nlog⁡QE_{\text{cell}} = E^\circ_{\text{cell}} - \dfrac{0.059}{n} \log Q

Substituting the values:

Ecell=2.00−0.0596log⁡(103)E_{\text{cell}} = 2.00 - \dfrac{0.059}{6} \log(10^3)

Ecell=2.00−0.0596×3E_{\text{cell}} = 2.00 - \dfrac{0.059}{6} \times 3

Ecell=2.00−0.0592E_{\text{cell}} = 2.00 - \dfrac{0.059}{2}

Ecell=2.00−0.0295=1.9705 VE_{\text{cell}} = 2.00 - 0.0295 = 1.9705\text{ V}

Answer: 1.9705 V1.9705\text{ V}
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