Sign in
12thPass logo
New chatPYQ LibraryDoubtsRank report
Sign in to see Recents

Your guest activity stays on this device

Sign in to save progress →
Sign in

Electrochemistry question

2022 · 24 Jun · Shift 1 · Q15
Guest · filters and generic practice availableBrowsing as a guest · PYQ filters and generic practice are available. Sign in only for personalised features and saved progress.
  1. PYQ Library
  2. /JEE Main
  3. /Chemistry
  4. /Electrochemistry
  5. /2022 · 24 Jun · Shift 1 · Q15

Electrochemistry question

2022 · 24 Jun · Shift 1 · Q15

JEE MainChemistryElectrochemistryNumerical+4 / −1
The cell potential for the following cell Pt |H2H_2H2​(g)|H+H^+H+ (aq)|| Cu2+Cu^{2+}Cu2+ (0.01 M)|CuCuCu(s) is 0.576 V at 298 K. The pH of the solution is ‾\underline{\hspace{2cm}}​. (Nearest integer) (Given : ECu2+/Cuo=0.34E_{C{u^{2 + }}/Cu}^o = 0.34ECu2+/Cuo​=0.34 V and 2.303 RTF=0.06{{2.303\,RT} \over F} = 0.06F2.303RT​=0.06 V)
Numerical answer
View written solutionFree

Correct answer: 5

  1. Write the cell reaction

The given cell is

Pt ∣H2(g)∣H+(aq)∣∣Cu2+(0.01 M)∣Cu(s)\text{Pt }| H_2(g)|H^+(aq) || Cu^{2+}(0.01\,M)|Cu(s)Pt ∣H2​(g)∣H+(aq)∣∣Cu2+(0.01M)∣Cu(s)

Left electrode is the hydrogen electrode and right electrode is the copper electrode.

  • Anode (oxidation): H2→2H++2e−H_2 \rightarrow 2H^+ + 2e^-H2​→2H++2e−

  • Cathode (reduction): Cu2++2e−→CuCu^{2+} + 2e^- \rightarrow CuCu2++2e−→Cu

Overall reaction: H2+Cu2+→2H++CuH_2 + Cu^{2+} \rightarrow 2H^+ + CuH2​+Cu2+→2H++Cu

  1. Find standard cell potential

Given: ECu2+/Cu∘=0.34 VE^\circ_{Cu^{2+}/Cu} = 0.34\,VECu2+/Cu∘​=0.34V EH+/H2∘=0 VE^\circ_{H^+/H_2} = 0\,VEH+/H2​∘​=0V

So, Ecell∘=Ecathode∘−Eanode∘=0.34−0=0.34 VE^\circ_{cell} = E^\circ_{cathode} - E^\circ_{anode} = 0.34 - 0 = 0.34\,VEcell∘​=Ecathode∘​−Eanode∘​=0.34−0=0.34V

  1. Apply Nernst equation

For the overall reaction, Q=[H+]2PH2[Cu2+]Q = \frac{[H^+]^2}{P_{H_2}[Cu^{2+}]}Q=PH2​​[Cu2+][H+]2​

Assuming H2H_2H2​ gas is at 1 atm1\,atm1atm, Q=[H+]2[Cu2+]Q = \frac{[H^+]^2}{[Cu^{2+}]}Q=[Cu2+][H+]2​

Given [Cu2+]=0.01=10−2[Cu^{2+}] = 0.01 = 10^{-2}[Cu2+]=0.01=10−2, Q=[H+]210−2Q = \frac{[H^+]^2}{10^{-2}}Q=10−2[H+]2​

Now, Ecell=Ecell∘−0.06nlog⁡QE_{cell} = E^\circ_{cell} - \frac{0.06}{n}\log QEcell​=Ecell∘​−n0.06​logQ

Here n=2n=2n=2, so 0.576=0.34−0.062log⁡([H+]210−2)0.576 = 0.34 - \frac{0.06}{2} \log\left(\frac{[H^+]^2}{10^{-2}}\right)0.576=0.34−20.06​log(10−2[H+]2​)

0.576=0.34−0.03log⁡([H+]210−2)0.576 = 0.34 - 0.03\log\left(\frac{[H^+]^2}{10^{-2}}\right)0.576=0.34−0.03log(10−2[H+]2​)

  1. Solve for [H+][H^+][H+]

Rearranging, 0.576−0.34=−0.03log⁡([H+]210−2)0.576 - 0.34 = -0.03\log\left(\frac{[H^+]^2}{10^{-2}}\right)0.576−0.34=−0.03log(10−2[H+]2​)

0.236=−0.03log⁡([H+]210−2)0.236 = -0.03\log\left(\frac{[H^+]^2}{10^{-2}}\right)0.236=−0.03log(10−2[H+]2​)

log⁡([H+]210−2)=−0.2360.03≈−7.867\log\left(\frac{[H^+]^2}{10^{-2}}\right) = -\frac{0.236}{0.03} \approx -7.867log(10−2[H+]2​)=−0.030.236​≈−7.867

So, [H+]210−2=10−7.867\frac{[H^+]^2}{10^{-2}} = 10^{-7.867}10−2[H+]2​=10−7.867

[H+]2=10−2⋅10−7.867=10−9.867[H^+]^2 = 10^{-2}\cdot 10^{-7.867} = 10^{-9.867}[H+]2=10−2⋅10−7.867=10−9.867

[H+]=10−4.9335[H^+] = 10^{-4.9335}[H+]=10−4.9335

Therefore, pH=−log⁡[H+]=4.9335\text{pH} = -\log[H^+] = 4.9335pH=−log[H+]=4.9335

Nearest integer: 5\boxed{5}5​

  1. Comparison with stored answer

Derived answer is 555, which matches the stored correct answer.

PreviousNext

More from Electrochemistry

  • The resistance of a conductivity cell containing 0.01 M KCl solution at 298 K is 1750 Ω. If the conductivity of 0.01 M KCl solution at 298 K is 0.152 × 10 − 3 S cm − 1, then the cell constant of the conductivity cell is ​×…2022 · Numerical
  • The cell potential for Zn​Zn2+(aq)​​Snx+​Sn is 0.801 V at 298 K. The reaction quotient for the above reaction is 10−2. The number of…2022 · Numerical
  • The spin-only magnetic moment value of M3+ ion (in gaseous state) from the pairs Cr3+ / Cr2+, Mn3+ / Mn2+, Fe3+ / Fe2+ and Co3+ / Co2+ that has negative standard electrode potential, is ​…2022 · Numerical
  • The molar conductivity of a conductivity cell filled with 10 moles of 20 mL NaCl solution is Λm1​ and that of 20 moles another identical cell heaving 80 mL NaCl solution is Λm2​. The conductivities exhibited by…2022 · MCQ
  • In a cell, the following reactions take place Fe2+→Fe3++e−2I−→I2​+2e−​EFe3+/Fe2+o​=0.77VEI2​/I−o​=0.54V​…2022 · Numerical
  • A solution of Fe2​(SO4​)3​ is electrolyzed for 'x' min with a current of 1.5 A to deposit 0.3482 g of Fe. The value of x is ​. [nearest integer] Given : 1 F = 96500 C mol − 1 Atomic mass of Fe = 56 g mol…2022 · Numerical
  • The correct order of reduction potentials of the following pairs is A. Cl2​/Cl− B. I2​/I− C. Ag+/Ag D. Na+/Na E. Li+/Li Choose the correct answer from the options given below.2022 · MCQ
  • The amount of charge in F(Faraday) required to obtain one mole of iron from Fe3​O4​ is ​. (Nearest Integer)2022 · Numerical