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Electrochemistry - ISC Class 12 Chemistry Questions with Answers, Page 4

77 past-paper questions on Electrochemistry from ISC Class 12 Chemistry papers (2027-2018), newest first, in full. Questions 61-77 are on this page, 20 to a page. Tap "Show answer" under a question to see its answer.

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2023 · 5 marks · NumericalOpen: The resistance of a conductivity cell with solution is . When the same cell is…
(a)[2.5]
The resistance of a conductivity cell with $0\cdot1\text{ M}$ $\text{KCl}$ solution is $200\text{ ohm}$. When the same cell is filled with $0\cdot02\text{ M}$ $\text{NaCl}$ solution, the resistance is $1100\text{ ohm}$. If the conductivity of $0\cdot1\text{ M}$ $\text{KCl}$ solution is $0\cdot0129\text{ ohm}^{-1}\text{ cm}^{-1}$, calculate the cell constant and molar conductivity of $0\cdot02\text{ M}$ $\text{NaCl}$ solution.
(b)[2.5]
The emf ($E^\circ_{\text{cell}}$) of the following reaction is $0\cdot89\text{ V}$: $3\text{Sn}^{4+} + 2\text{Cr} \rightarrow 3\text{Sn}^{2+} + 2\text{Cr}^{3+}$ Calculate the value of $\Delta G^\circ$ for the reaction. Predict whether the above reaction will be spontaneous or not.

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2023 · 2 marks · NumericalOpen: Calculate the emf of the following cell at . Given , ,
Calculate the emf of the following cell at $298\text{ K}$. $\text{Cu} / \text{Cu}^{2+}(0\cdot025\text{ M}) // \text{Ag}^+(0\cdot005\text{ M}) / \text{Ag}$ Given $E^\circ_{\text{Cu}^{2+}/\text{Cu}} = 0\cdot34\text{ V}$, $E^\circ_{\text{Ag}^+/\text{Ag}} = 0\cdot80\text{ V}$, $1\text{ Faraday} = 96500\text{ C mol}^{-1}$

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2022 · 2 marks · Short answerOpen: The limiting molar conductivities ( ) for NaCl, KBr and KCl are 126, 152 and…
The limiting molar conductivities ($\Lambda^\infty_m$) for NaCl, KBr and KCl are 126, 152 and $150\text{ ohm}^{-1}\text{ cm}^2\text{ mol}^{-1}$ respectively.
(i)
The molar conductivity at infinite dilution for NaBr is:
  • (a)128 ohm-1 cm2 mol-1
  • (b)176 ohm-1 cm2 mol-1
  • (c)278 ohm-1 cm2 mol-1
  • (d)302 ohm-1 cm2 mol-1
(ii)
The law applied to determine the molar conductivity of infinite dilution is known as:
  • (a)Faraday’s Law
  • (b)Avogadro’s Law
  • (c)Kohlrausch’s Law
  • (d)Ohm’s Law

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2022 · 1 mark · MCQOpen: When zinc granule is dipped into copper sulphate solution, copper is…
When zinc granule is dipped into copper sulphate solution, copper is precipitated because:
  • (a)Both copper and zinc have a positive reduction potential.
  • (b)Both copper and zinc have a negative reduction potential.
  • (c)Reduction potential of zinc is higher than that of copper.
  • (d)Reduction potential of copper is higher than that of zinc.

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2022 · 2 marks · Short answerOpen: When two Faradays of electricity is passed through an aqueous solution of CuSO4…
When two Faradays of electricity is passed through an aqueous solution of CuSO4 and an aqueous solution of AgNO3. (Atomic weight of Cu = 63.5 g mol-1, Ag = 108 g mol-1)
(i)
The mass of copper deposited at the cathode is:
  • (a)127.02 g
  • (b)63.50 g
  • (c)31.75 g
  • (d)15.87 g
(ii)
The mass of silver deposited at the cathode is:
  • (a)54 g
  • (b)108 g
  • (c)216 g
  • (d)270 g

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2022 · 2 marks · Short answerOpen: The standard electrode potential for the reaction is: (I) (II) The will be: The…
The standard electrode potential for the reaction is: (I) $\text{Ag}^+ + \text{e}^- \rightarrow \text{Ag}(s); \, E^\circ_{\text{Ag}^+/\text{Ag}} = +0.80\text{ V}$ (II) $\text{Sn}^{2+} + 2\text{e}^- \rightarrow \text{Sn}(s); \, E^\circ_{\text{Sn}^{2+}/\text{Sn}} = -0.14\text{ V}$
(i)
The $E^\circ_{\text{cell}}$ will be:
  • (a)0.66 V
  • (b)0.88 V
  • (c)0.94 V
  • (d)1.08 V
(ii)
The value of standard Gibbs energy ($\Delta G^\circ$) will be: ($F = 96,000\text{ C mol}^{-1}$)
  • (a)-181.42 kJ
  • (b)-90.71 kJ
  • (c)-45.36 kJ
  • (d)-22.68 kJ

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2020 · 3 marks · NumericalOpen: Calculate the degree of dissociation ( ) of acetic acid, if its molar…
Calculate the degree of dissociation ($\alpha$) of acetic acid, if its molar conductivity ($\Lambda_m$) is $39\cdot05\text{ S cm}^2\text{ mol}^{-1}$ (Given $\lambda^\circ_{(\text{H}^+)} = 349\cdot6\text{ S cm}^2\text{ mol}^{-1}$ and $\lambda^\circ_{(\text{CH}_3\text{COO}^-)} = 40\cdot95\text{ S cm}^2\text{ mol}^{-1}$)

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2020 · 3 marks · NumericalOpen: Calculate the emf and for the given cell at : Given: , ( , )
Calculate the emf and $\Delta G$ for the given cell at $25^\circ\text{C}$: $\text{Cr}(s) \mid \text{Cr}^{3+}(0\cdot1\text{ M}) \parallel \text{Fe}^{2+}(0\cdot01\text{ M}) \mid \text{Fe}(s)$ Given: $E^\circ_{\text{Cr}^{3+}/\text{Cr}} = -0\cdot74\text{ V}$, $E^\circ_{\text{Fe}^{2+}/\text{Fe}} = -0\cdot44\text{ V}$ ($1\text{ F} = 96500\text{ C}$, $R = 8\cdot314\text{ J K}^{-1}\text{mol}^{-1}$)

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2019 · 5 marks · Short answerOpen: Define the following terms: (1) Specific conductance (2) Kohlrausch’s Law The…
(i)
Define the following terms: (1) Specific conductance (2) Kohlrausch’s Law
(ii)
The resistance of a conductivity cell containing $0\cdot001\text{ M KCl}$ solution at $298\text{ K}$ is $1500\text{ ohm}$. What is the cell constant and molar conductivity of $0\cdot001\text{ M KCl}$ solution, if the conductivity of this solution is $0\cdot146 \times 10^{-3}\text{ ohm}^{-1}\text{ cm}^{-1}$ at $298\text{ K}$?

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2019 · 5 marks · Short answerOpen: Calculate the mass of silver deposited at cathode when a current of is passed…
(i)
Calculate the mass of silver deposited at cathode when a current of $2\text{ amperes}$ is passed through a solution of $\text{AgNO}_3$ for $15\text{ minutes}$. (at. wt. of $\text{Ag} = 108, 1\text{ F} = 96,500\text{ C}$)
(ii)
Calculate the emf and $\Delta G$ for the cell reaction at $298\text{ K}$: $\text{Mg}(s) \mid \text{Mg}^{2+}(0\cdot1\text{M}) \parallel \text{Cu}^{2+}(0\cdot01\text{M}) \mid \text{Cu}(s)$ Given $E^\circ_\text{cell} = 2\cdot71\text{ V}$, $1\text{F} = 96,500\text{ C}$

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2018 · 5 marks · Short answerOpen: Resistance of a conductivity cell filled with solution is . If the resistance…
(i)[3.0]
Resistance of a conductivity cell filled with $0\cdot1\text{ mol L}^{-1}\text{ KCl}$ solution is $100\ \Omega$. If the resistance of the same cell when filled with $0\cdot02\text{ mol L}^{-1}\text{ KCl}$ solution is $520\ \Omega$, calculate the conductivity and molar conductivity of $0\cdot02\text{ mol L}^{-1}\text{ KCl}$ solution. The conductivity of $0\cdot1\text{ mol L}^{-1}\text{ KCl}$ solution is $1\cdot29 \times 10^{-2}\ \Omega^{-1}\text{cm}^{-1}$.
(ii)[2.0]
Define the following terms: (1) Limiting molar conductivity. (2) Fuel cell.

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2018 · 5 marks · Short answerOpen: Calculate emf of the following cell at : [Given , ] State Faraday’s first law…
(i)[3.0]
Calculate emf of the following cell at $298\text{ K}$: $\text{Mg}(s) \mid \text{Mg}^{2+}(0\cdot1\text{ M}) \parallel \text{Cu}^{2+}(0\cdot01\text{ M}) \mid \text{Cu}(s)$ [Given $E^\circ_\text{cell} = +2\cdot71\text{ V}$, $1\text{ Faraday} = 96500\text{ C mol}^{-1}$]
(ii)[2.0]
State Faraday’s first law of electrolysis. Calculate the charge required in terms of Faraday for the reduction of $1\text{ mole}$ of $\text{Cu}^{2+}$ to $\text{Cu}$.

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2018 · 5 marks · Short answerOpen: The specific conductivity of a solution containing of anhydrous (mol. wt. ) in…
(i)
The specific conductivity of a solution containing $5\text{ g}$ of anhydrous $\text{BaCl}_2$ (mol. wt. $= 208$) in $1000\text{ cm}^3$ of a solution is found to be $0\cdot0058\text{ ohm}^{-1}\text{cm}^{-1}$. Calculate the molar and equivalent conductivity of the solution.
(ii)
What is an electrochemical series? How is it useful in predicting whether a metal can liberate hydrogen from acid or not?

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2018 · 5 marks · Short answerOpen: Calculate the emf and for the cell reaction at : Given and . Define the…
(i)
Calculate the emf and $\Delta G^\circ$ for the cell reaction at $25^\circ\text{C}$: $\text{Zn}(s) \mid \text{Zn}^{2+}(aq, 0\cdot1\text{ M}) \parallel \text{Cd}^{2+}(aq, 0\cdot01\text{ M}) \mid \text{Cd}(s)$ Given $E^\circ_{\text{Zn}^{2+}/\text{Zn}} = -0\cdot763\text{ V}$ and $E^\circ_{\text{Cd}^{2+}/\text{Cd}} = -0\cdot403\text{ V}$.
(ii)
Define the following terms: (1) Equivalent conductivity (2) Corrosion of metals

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