Electrochemistry - Physical Chemistry - Chemistry Previous Year Questions

On passing a current of 1.2 A through a solution of salt of copper for $40 \mathrm{~min}, 0.96 \mathrm{~g}$ of copper was deposited. The equivalent weight of copper in g is

At 300 K , the conductivity of $0.01 \mathrm{~mol} \mathrm{dm}^{-3}$ aqueous solution of acetic acid is $19.5 \times 10^{-5} \mathrm{mho} \mathrm{cm}^{-1}$ and limiting molar conductivity of acetic acid at the same temperature is $390 \mathrm{mho} \mathrm{cm}^2 \mathrm{~mol}^{-1}$. The degree of dissociation of acetic acid is

$A$ and $B$ are two metals. The standard reduction potential of $A^{+}(a q) / A(s)$ and $B^{+}(a q) / B(s)$ are -0.5 V and +0.5 V respectively. What is the $\log K_c$ value for the following reaction at 298 K ?

$$\begin{aligned} & A(s)+B^{+}(a q) \rightleftharpoons A^{+}(a q)+B(s) \\ & \left(\text { Given }: \frac{2.303 R T}{F}=0.06 \mathrm{~V}\right) \end{aligned}$$

The conductivity of a solution of concentration $0.1 \mathrm{~mol} \mathrm{~L}^{-1}$ of a weak monobasic acid $(\mathrm{HA})$ (in $\mathrm{S} \mathrm{cm}^{-1}$ ) is (Given : $\Lambda^{\circ}{ }_{\mathrm{HA}}=400 \mathrm{Scm}^2 \mathrm{~mol}^{-1}$ and degree of dissociation ( $\alpha$ ) of $\mathrm{H} A=0.02$ )

The reduction potential of a half-cell consisting of a Pt electrode immersed in $2.0 \mathrm{M} \mathrm{Fe}^{2+}$ and $0.02 \mathrm{M} \mathrm{Fe}^{3+}$ solution (in V) is

Given : $\left(\frac{2.303 R T}{F}=0.059, E_{\mathrm{Fe}^{3+} \mid \mathrm{Fe}^{2+}}^{\circ}=0.771 \mathrm{~V}\right)$

A current of 15.0 A is passed through a solution of $\mathrm{CrCl}_2$ for 45 minutes. The volume of $\mathrm{Cl}_2$ (in L ) obtained at the anode at 1 atm and 273 K is around (IF $=96500 \mathrm{C} \mathrm{mol}^{-1}$, atomic wt. of $\mathrm{Cl}=35.5, R=0.082 \mathrm{L}-\mathrm{atm} \mathrm{K}^{-1} \mathrm{~mol}^{-1}$ )

The maximum work that can be obtained from the following cells is

$$X\left|X^{2+}(a q) \| Y^{+}(a q)\right| Y$$

Given, $E_{X^{2+} / X}^{\circ}=-1.7 \mathrm{~V}, E_{Y^{2+} / Y}^{\circ}=0.8 \mathrm{~V}$

The standard electrode potentials of $\mathrm{Ag}^{+} / \mathrm{Ag}$ is +0.80 V and $\mathrm{Cu}^{+} / \mathrm{Cu}$ is +0.34 V . If these electrodes are connected through a salt-bridge, which of the following statements is correct?

In two separate experiments, the same quantity of electricity was passed through silver and gold solutions. [Assume ' $l$ ' constant]. The amounts of Ag and Au deposited are 2.15 and 1.31 g , respectively. The valency of gold is

[atomic mass of $\mathrm{Ag}=107.9$; $\mathrm{Au}=197$ ]

Given, $E_{\mathrm{Mn}^{7+} / \mathrm{Mn}^{2+}}^{\circ}=1.51 \mathrm{~V}, E_{\mathrm{Mn}^{4+} / \mathrm{Mn}^{2+}}^{\circ}=1.23 \mathrm{~V}$ Calculate the $E_{\mathrm{Mn}^{7+} / \mathrm{Mn}^{4+}}^{\circ}$.

The $E^{\circ}$ of $\mathrm{Ce}^{4+} / \mathrm{Ce}^{3+}=1.6 \mathrm{~V}, \mathrm{Fe}^{3+} / \mathrm{Fe}^{2+}=0.76 \mathrm{~V}$ the $E^{\circ}$ of $\mathrm{Fe}^{3+}$ oxidising $\mathrm{Ce}^{3+}$ is

Electrolysis of aqueous $\mathrm{Na}_2 \mathrm{SO}_4$ was carried out by passing a current of 3 ampere for 10 min . The volume of the gas (in litre) at STP at the anode of the cell is approximately

The variation of $\lambda_{\mathrm{m}}$ of acetic acid with concentration is correctly represented as

A solution of $\mathrm{Fe}^{2+}$ is titrated potentiometrically using $\mathrm{Ce}^{4+}$ solution. When $80 \% \mathrm{Fe}^{2+}$ is titrated, the EMF of the system in $V$ is

(Given, $E^{\circ} \mathrm{Fe}^{3+} / \mathrm{Fe}^{2+}=0.77 \mathrm{~V}$ and $\left.\mathrm{Fe}^{2+}+\mathrm{Ce}^{4+} \longrightarrow \mathrm{Fe}^{3+}+\mathrm{Ce}^{3+}\right) (\log 2=0.3, \log 3=0.5, \log 4=0.6)$

What is the standard cell potential for the reaction with $K=1$ (equilibrium constant)

Copper is to be electrodeposited on a nickel block of $(20 \times 5) \mathrm{cm}^2$ area by using $\mathrm{CuSO}_4$ as electrolyte. How much quantity of electricity is needed to deposit a 3.6 $\mu \mathrm{m}$ layer of copper?

[Atomic weight of $\mathrm{Cu}=63.5 \mathrm{~mol}^{-1}$ Density of $\mathrm{CuSO}_4=8.9 \mathrm{~g} / \mathrm{cc}$ ]

$\mathrm{Mg}^{2+}$ displaces hydrogen from acids but copper does not. A galvanic cell prepared by combining $\mathrm{Cu} / \mathrm{Cu}^{2+}$ and $\mathrm{Mg} / \mathrm{Mg}^{2+}$ has an EMF of 2.71 V at 298 K . If the potential of copper electrode is 0.34 V , what is the reduction potential of Mg electrode?