Electrochemistry

Match List - I with List - II.

Choose the correct answer from the options given below :

Which of the following has least tendency to liberate $\mathrm{H_2}$ from mineral acids ?

Resistance of a conductivity cell (cell constant 129 m$^{-1}$) filled with 74.5 ppm solution of KCl is 100 Ω (labelled as solution 1). When the same cell is filled with KCl solution of 149 ppm, the resistance is 50 Ω (labelled as solution 2). The ratio of molar conductivity of solution 1 and solution 2 is i.e. $\dfrac{\Lambda_1}{\Lambda_2}=x\times10^{-3}$. The value of $x$ is _______. (Nearest integer)

Given, molar mass of KCl is 74.5 g mol$^{-1}$.

For a cell, Cu(s) | Cu$^{2+}$(0.001 M) || Ag$^+$ (0.01 M) | Ag (s) the cell potential is found to be 0.43 V at 298 K. The magnitude of standard electrode potential for Cu$^{2+}$/Cu is _______ $\times10^{-2}$ V.

[Given : $E^\ominus_{\mathrm{Ag^+/Ag}}$ = 0.80 V and $\dfrac{2.303RT}F$ = 0.06 V]

The E° (volt) values are : Al$^{3+}$/Al, −1.66, Sc$^{3+}$/Sc, −2.08, Fe$^{3+}$/Fe$^{2+}$, +0.77, Hg$_2^{2+}$/Hg, +0.79. Arrangement of cations, Al$^{3+}$, Sc$^{3+}$, Fe$^{3+}$ and Hg$_2^{2+}$ in decreasing order of oxidizing strength is

For the given cell Zn(s) | Zn$^{2+}$ (C$_1$ M) || Zn$^{2+}$ (C$_2$ M) | Zn(s) the change in Gibbs energy (ΔG) will be zero when $\dfrac{C_1}{C_2}$ is equal to _______.

Some standard electrode potentials at 298 K are given below:

Couple	$E^\circ$
$\ce{Pb^{2+}/Pb}$	−0.13 V
$\ce{Ni^{2+}/Ni}$	−0.24 V
$\ce{Cd^{2+}/Cd}$	−0.40 V
$\ce{Fe^{2+}/Fe}$	−0.44 V

To a solution containing 0.001 M of $\mathbf X^{2+}$ and 0.1 M of $\mathbf Y^{2+}$, the metal rods $\mathbf X$ and $\mathbf Y$ are inserted (at 298 K) and connected by a conducting wire. This resulted in dissolution of $\mathbf X$. The correct combination(s) of $\mathbf X$ and $\mathbf Y$, respectively, is(are)

(Given: Gas constant, R = 8.314 J K$^{-1}$ mol$^{-1}$, Faraday constant, F = 96500 C mol$^{-1}$)

The value of $\alpha$ is ____.

The value of $\mathbf y$ is ____.

The electrode potential of M$^{2+}$/M of 3d-series elements shows positive value for :

Consider a 70% efficient hydrogen-oxygen fuel cell working under standard conditions at 1 bar and 298 K. Its cell reaction is

$$\ce{H2(g) + 1/2 O2(g) -> H2O(l)}.$$

The work derived from the cell on the consumption of $1.0\times10^{-3}$ mol of $\ce{H2(g)}$ is used to compress 1.00 mol of a monoatomic ideal gas in a thermally insulated container. What is the change in the temperature (in K) of the ideal gas?

The standard reduction potentials for the two half-cells are given below.

$$\ce{O2(g) + 4H+(aq) + 4e- -> 2H2O(l)},\quad E^0 = 1.23\ \text{V},$$

$$\ce{2H+(aq) + 2e- -> H2(g)},\quad E^0 = 0.00\ \text{V}.$$

Use $F = 96500\ \mathrm{C\,mol^{-1}}$, $R = 8.314\ \mathrm{J\,mol^{-1}\,K^{-1}}$.

Molar conductivity $(\Lambda_m)$ of aqueous solution of sodium stearate, which behaves as a strong electrolyte, is recorded at varying concentrations $(c)$ of sodium stearate. Which one of the following plots provides the correct representation of micelle formation in the solution?

(critical micelle concentration (CMC) is marked with an arrow in the figures)

For the electrochemical cell,

$$\ce{Mg(s) | Mg^{2+}(aq, 1 M) || Cu^{2+}(aq, 1 M) | Cu(s)}$$

the standard emf of the cell is 2.70 V at 300 K. When the concentration of $\ce{Mg^{2+}}$ is changed to $x$ M, the cell potential changes to 2.67 V at 300 K. The value of $x$ is ______.

(given, $\dfrac FR = 11500\ \mathrm{K\,V^{-1}}$, where $F$ is the Faraday constant and $R$ is the gas constant, $\ln(10) = 2.30$)

The correct option(s) to distinguish nitrate salts of $\mathrm{Mn^{2+}}$ and $\mathrm{Cu^{2+}}$ taken separately is (are)

Consider an electrochemical cell: $\mathrm{A(s)\,|\,A^{n+}(aq,\ 2\ M)\,||\,B^{2n+}(aq,\ 1\ M)\,|\,B(s)}$. The value of $\Delta H^\ominus$ for the cell reaction is twice that of $\Delta G^\ominus$ at 300 K. If the emf of the cell is zero, the $\Delta S^\ominus$ (in J K$^{-1}$ mol$^{-1}$) of the cell reaction per mole of B formed at 300 K is ____.

(Given: ln(2) = 0.7, $R$ (universal gas constant) = 8.3 J K$^{-1}$ mol$^{-1}$. $H$, $S$ and $G$ are enthalpy, entropy and Gibbs energy, respectively.)

The conductance of a 0.0015 M aqueous solution of a weak monobasic acid was determined by using a conductivity cell consisting of platinized Pt electrodes. The distance between the electrodes is 120 cm with an area of cross section of $1\ \mathrm{cm^2}$. The conductance of this solution was found to be $5 \times 10^{-7}$ S. The pH of the solution is 4. The value of limiting molar conductivity $(\Lambda_m^o)$ of this weak monobasic acid in aqueous solution is $Z \times 10^2\ \mathrm{S\,cm^{-1}\,mol^{-1}}$. The value of $Z$ is

For the following cell,

$$\mathrm{Zn(s)\,|\,ZnSO_4(aq)\,\|\,CuSO_4(aq)\,|\,Cu(s)}$$

when the concentration of $\mathrm{Zn^{2+}}$ is 10 times the concentration of $\mathrm{Cu^{2+}}$, the expression for $\Delta G$ (in $\mathrm{J\,mol^{-1}}$) is

[F is Faraday constant; R is gas constant; T is temperature; $E^o(cell) = 1.1$ V]

Given $E^\circ_{\ce{Cl2/Cl-}}=1.36$ V, $E^\circ_{\ce{Cr^3+/Cr}}=-0.74$ V, $E^\circ_{\ce{Cr2O7^2-/Cr^3+}}=1.33$ V, $E^\circ_{\ce{MnO4-/Mn^2+}}=1.51$ V.

Among the following, the strongest reducing agent is :

What is the standard reduction potential (E°) for $\ce{Fe^3+ -> Fe}$ ?

Given that :

$\ce{Fe^2+ + 2e- -> Fe}$ ; $E^\circ_{\ce{Fe^2+/Fe}}=-0.47$ V

$\ce{Fe^3+ + e- -> Fe^2+}$ ; $E^\circ_{\ce{Fe^3+/Fe^2+}}=+0.77$ V

Consider the following standard electrode potentials (E° in volts) in aqueous solution :

Element	$\ce{M^3+/M}$	$\ce{M+/M}$
Al	−1.66	+0.55
Tl	+1.26	−0.34

Based on these data, which of the following statements is correct ?