Electro chemistry practice · Mixed difficulty

If the ${H^ + }$ concentration is decreased from 1 M to ${10^{ - 4}}$ M at ${25^ \circ }C$  for the couple $MnO_4^ - /M{n^{(2 + )}}$, then the oxidising power of the $MnO_4^ - /M{n^{(2 + )}}$ couple decreases by

The formula $\mathrm{\alpha } = \frac{{{\mathrm{\Lambda }_\mathrm{v}}}}{{{\mathrm{\Lambda }_\infty }}}$ is valid for :

Charge required to liberate $11.5 \mathrm{~g}$ sodium is

Standard potentials $\left(E^{\circ}\right)$ for some half-reactions are given below:

(i) ${Sn}^{4+}+2 {e}^{-} \rightarrow {Sn}^{2+} ; E^{\circ}=+0.15 {~V}$

(ii) $2 {Hg}^{2+}+2 {e}^{-} \rightarrow {Hg}_2{ }^{2+} ; E^{\circ}=+0.92 {~V}$

(iii) ${PbO}_2+4 {H}^{+}+2 {e}^{-} \rightarrow {Pb}^{2+}+2 {H}_2 {O} ; E^{\circ}=+1.45 {~V}$

Based on the above, which one of the following statements is correct?

A $0.5 {M} {NaOH}$ solution offers a resistance of $31.6 {ohm}$ in a conductivity cell at room temperature. What shall be the approximate molar conductance of this ${NaOH}$ solution if cell constant of the cell is $0.367 {~cm}^{-1}$.

An electrochemical cell is constructed as:

${\text{Zn}}\left| {{\text{Z}}{{\text{n}}^{2 + }}(0.1{\text{M}})||{{\text{H}}^ + }({\text{XM}})} \right|\mathop {\left( {{{\text{H}}_2}} \right){\text{Pt}}}\limits_{1\,{\text{bar}}} {\text{; E}}_{{\text{Z}}{{\text{n}}^{2 + }}\mid {\text{Zn}}}^0 = - 0.76\;{\text{V}}$

If emf of cell is $0.17 \mathrm{~V}$ then $\mathrm{pH}$ of cathodic compartment is:

Assertion:The electrode potential of SHE is zero.

Reason: SHE is a standard reference electrode.

An aqueous solution of $0.02 \, \mathrm{M} \, {MgSO}_4$ electrolysed by passing a current of $9.65 \mathrm{~A}$ for 30 min. Mass of product obtained at cathode is

The standard cell potential for the cell is : $\mathrm{Zn}\left| {\mathrm{Z}{\mathrm{n}^{2 + }}\left( {1M} \right)} \right|\left| {\mathrm{C}{\mathrm{u}^{2 + }}\left( {1M} \right)} \right|\mathrm{Cu}$
$\left[ {{E^ \circ }{\kern 1pt} {\kern 1pt}{\rm{for {\kern 1pt} {\kern 1pt}Z}}{\mathrm{n}^{2 + }}/\mathrm{Zn} = - 0.76;{E^ \circ }{\kern 1pt} {\kern 1pt}{\rm{for {\kern 1pt} {\kern 1pt}C}}{\mathrm{u}^{2 + }}/\mathrm{Cu} = + 0.34} \right]$

${E^ \circ }$ of an electrode is :

In acidic medium $\mathrm{MnO}_4^ -$ is converted to $\mathrm{M}{\mathrm{n}^{2 + }}$ . The quantity of electricity in faraday required to reduce 0.5 mole of $\mathrm{MnO}_4^ -$ to $\mathrm{M}{\mathrm{n}^{2 + }}$ would be

The fraction of the total current carried by an ion is known as:

$Zn$ amalgam is prepared by electrolysis of aqueous $ZnCl_2$ using $Hg$ cathode $(9 \mathrm{gm})$. How much current is to be passed through $ZnCl_2$ solution for 1000 seconds to prepare a $Zn$ Amalgam with $25 \% Zn$ by wt. $(Zn=65.4)$

On electrolysis of acidified water, if volume of hydrogen liberated is $5.6 \mathrm{~cm}^3$, then the volume of oxygen liberated equal to:

The potential of Hydrogen electrode $\left( {{P_{{H_2}}} = 1\mathrm{ atm },\mathrm{ }\left[ {{H^ + }} \right] = O.1M} \right)$ at ${25^\mathrm{o}}C$ will be

If the pressure of $\mathrm{H}_2(\mathrm{g})$ is increased from $1 \mathrm{~atm}$ to $100 \mathrm{~atm}$ keeping $\left[\mathrm{H}^{+}\right]$ constant at $1 \mathrm{M}$, the change in reduction potential of hydrogen half cell at $25^{\circ} \mathrm{C}$ will be:

By passage of 1F of electricity, through 1L of 1M solution
of an electrolyte which is not obtained

The resistance of 0.5 $N$ solution of an electrolyte in a conductivity cell was found to be 45 ohms. The equivalent conductivity of the same solution is …..if the electrodes in the cell are 2.2 cm apart and have an area of 3.8 $\mathrm{c}{\mathrm{m}^2}$.

Passage of three faraday of charge through aqueous solution of $\mathrm{AgN}{\mathrm{O}_3},\mathrm{CuS}{\mathrm{O}_4},\mathrm{Al}{\left( {\mathrm{N}{\mathrm{O}_3}} \right)_3}$ and NaCl will deposit metals at the cathode in the molar ratio of:

Tell which of the following statements accurately describes the effect of adding $\mathrm{CN}^{-}$ to the cathode of a cell with a cell reaction:

$\mathrm{Cd}+2 \mathrm{Ag}^{+} \rightarrow 2 \mathrm{Ag}+\mathrm{Cd}^{2+}, E^{\circ}=1.2 \mathrm{~V}$

Cathode used in Leclanche cell is

Passage of electricity through dil ${H}_2 {SO}_4$ for 1 hour liberates a total of $224\, \mathrm{ml}$ of ${H}_2$ at S.T.P. The magnitude of current would be :-

Galvanic cell is A device in which

Assertion: Molar conductivity of $\mathrm{CH}_3 \mathrm{COOH}$ increases with dilution.

Reason: The graph between $\lambda \mathrm{m} \mathrm{v} / \mathrm{s}(\mathrm{C})^{1 / 2}$ is a straight line for $\mathrm{CH}_3 \mathrm{COOH}$.

Using the SRP values given below, decide which of the statements I, II, III and IV are correct.
$\begin{array}{l} F{e^{2 + }} + 2{e^ - }\underset{{}}{\overset{{}}{\leftrightharpoons}}Fe\,;\,{E^\mathrm{o}} = - 0.44\,V\\ C{u^{ + 2}} + 2{e^ - }\underset{{}}{\overset{{}}{\leftrightharpoons}}Cu\,;\,{E^\mathrm{o}} = + 0.34\,V\\ A{g^ + } + {e^ - }\underset{{}}{\overset{{}}{\leftrightharpoons}}Ag\,;\,{E^\mathrm{o}} = + 0.80\,V \end{array}$
(I) Copper can displace iron from $FeS{O_4}$ solution
(II) Iron can displace copper from $CuS{O_4}$ solution
(III) Silver can displace copper from $CuS{O_4}$ solution
(IV) Iron can displace silver from $AgN{O_3}$ solution

Out of $Cu, Ag, Fe$ and $Zn$, the metal which can displace all others form their salt solutions is:

The conductivity of 0.1 (M) $\mathrm{NaOH}$ solution is 0.0221 $\mathrm{ohm}^{-1} \mathrm{~cm}^{-1}$. When an equal volume of 0.1 (M) $\mathrm{HCl}$ solution is added, the conductivity decreases to 0.0056 $\mathrm{ohm}^{-1} \mathrm{~cm}^{-1}$.
A further addition of $\mathrm{HCl}$ solution, the volume of which is equal to that of the first portion added, the conductivity increases to $0.017 \mathrm{ohm}^{-1} \mathrm{~cm}^{-1}$. What is the molar conductance at infinite dilution of $\mathrm{H}_2 \mathrm{O}$ in ohm ${ }^{-1}$ $\mathrm{cm}^2 \mathrm{~mol}^{-1}$ in nearest possible integers ?

Statement (S): Conductivity of weak electrolytic solution decreases with dilution whereas equivalent conductivity, molar conductivity increases with dilution.
Explanation (E): On dilution, the ionic mobility and number of ions present in solution increases but number of ions per mL decreases.

In acidic medium $\mathrm{MnO}_4^ -$ is converted to $\mathrm{M}{\mathrm{n}^{2 + }}$ . The quantity of electricity in faraday required to reduce 0.5 mole of $\mathrm{MnO}_4^ -$ to $\mathrm{M}{\mathrm{n}^{2 + }}$ would be

If mercury is used as cathode in the electrolysis of aqueous $NaCl$ solution, the ions discharged at cathode is