Redox Reactions and Electrochemistry — JEE Main PYQs

In a fuel cell methanol is used as fuel and oxygen gas is used as an oxidizer. The reaction is ${\mathrm{CH}}_3\mathrm{OH}(\ell )+\frac{3}{2}{\mathrm{O}}_2(\mathrm{g})\to {\mathrm{CO}}_2(\mathrm{g})+2{\mathrm{H}}_2\mathrm{O}(\ell )$ At 298 K standard Gibb's energie …

Given : ${\mathrm{E}}_{{\mathrm{Fe}}^{3+}/\mathrm{Fe}}^{\circ }=-0.036\mathrm{V},{\mathrm{E}}_{{\mathrm{Fe}}^{2+}/\mathrm{Fe}}^{\circ }=-0.439\mathrm{V}$. The value of standard electrode potential for the change, …

Given ${\mathrm{E}}_{{\mathrm{Cr}}^{3+}/\mathrm{Cr}}^{\circ }=-0.72\mathrm{V},{\mathrm{E}}_{{\mathrm{Fe}}^{2+}/\mathrm{Fe}}^{\circ }=-0.42\mathrm{V}$. The potential for the cell …

The cell, $\mathrm{Zn}|{\mathrm{Zn}}^{2+}(1\mathrm{M})||{\mathrm{Cu}}^{2+}(1\mathrm{M})|\mathrm{Cu}$ (${\mathrm{E}}_{\text{cell}}^0=1.10\mathrm{V}$), was allowed to be completely discharged at 298 K. The relative concentration of ${\mathrm{Zn}}^{2+}$ to ${\mathrm{Cu}}^{2+}$ …

The equivalent conductances of two strong electrolytes at infinite dilution in ${\mathrm{H}}_2\mathrm{O}$ (where ions move freely through a solution) at $25^{\circ }\mathrm{C}$ are given below: …

The molar conductivities ${\wedge }_{\mathrm{NaOAc}}^{\circ }$ and ${\wedge }_{\mathrm{HCl}}^{\circ }$ at infinite dilution in water at $25^{\circ }\mathrm{C}$ are 91.0 and $426.2\mathrm{S}{\mathrm{cm}}^2/\mathrm{mol}$ respectively. To calculate …

Given the data at $25^{\circ }\mathrm{C}$,
$\mathrm{Ag}+{\mathrm{I}}^{-}⟶\mathrm{AgI}+{\mathrm{e}}^{-};{\mathrm{E}}^{\circ }=0.152\mathrm{V}$
$\mathrm{Ag}⟶{\mathrm{Ag}}^{+}+{\mathrm{e}}^{-};{\mathrm{E}}^{\circ }=-0.800\mathrm{V}$
What is the value …

Resistance of a conductivity cell filled with a solution of an electrolyte of concentration 0.1 M is $100\Omega$. The conductivity of this solution is $1.29\mathrm{S}{\mathrm{m}}^{-1}$. Resistance of the same cell when filled with 0.02 M of the same solution is $520\Omega$. T …

The highest electrical conductivity of the following aqueous solutions is of

Aluminium oxide may be electrolysed at $1000^{\circ }\mathrm{C}$ to furnish aluminium metal (Atomic mass $=27\mathrm{amu};1$ Faraday $=96,500$ Coulombs). The cathode reaction is ${\mathrm{Al}}^{3+}+3{\mathrm{e}}^{-}⟶{\mathrm{Al}}^{\circ }$
To prepare 5.12 kg of alumi …

Calculate ${\Lambda }_{\mathrm{HOAc}}^{\infty }$ Using appropriate molar conductances of the electrolytes listed above at infinite dilution in ${\mathrm{H}}_2\mathrm{O}$ at $25^{\circ }\mathrm{C}$
| Electrolyte | KCl | ${\mathrm{KNO}}_3$ | HCl | NaOAc | NaCl ||-------------| …

The oxidation state of chromium in the final product formed by the reaction between KI and acidified potassium dichromate solution is

In hydrogen - oxygen fuel cell, combustion of hydrogen occurs to

Consider the following ${\mathrm{E}}^{\circ }$ values
${\mathrm{E}}_{{\mathrm{Fe}}^{3+}/{\mathrm{Fe}}^{2+}}^{\circ }=0.77\mathrm{V}$
${\mathrm{E}}_{{\mathrm{Sn}}^{2+}/\mathrm{Sn}}^{\circ }=-0.14\mathrm{V}$

Under standard conditions the potential for the reaction …

The standard e.m.f of a cell, involving one electron change is found to be 0.591 V at $25^{\circ }\mathrm{C}$. The equilibrium constant of the reaction is ( $F=96,500\mathrm{C}{\mathrm{mol}}^{-1}:R=8.314{\mathrm{JK}}^{-1}{\mathrm{mol}}^{-1}$ )

The limiting molar conductivities ${\Lambda }^{\circ }$ for $\mathrm{NaCl},\mathrm{KBr}$ and KCl are 126, 152 and $150\mathrm{S}{\mathrm{cm}}^2{\mathrm{mol}}^{-1}$ respectively. The ${\Lambda }^{\circ }$ for NaBr is

In a cell that utilises the reaction $\mathrm{Zn}(\mathrm{s})+2{\mathrm{H}}^{+}(\mathrm{aq})⟶{\mathrm{Zn}}^{2+}(\mathrm{aq})+{\mathrm{H}}_2(\mathrm{g})$ addition of ${\mathrm{H}}_2{\mathrm{SO}}_4$ to cathode compartment, will

The ${\mathrm{E}}_{{\mathrm{M}}^{+3}/{\mathrm{M}}^{2+}}^{\circ }$ values for $\mathrm{Cr},\mathrm{Mn},\mathrm{Fe}$ and Co are $-0.41,+1.57,+0.77$ and +1.97 V respectively. For which one of these metals the change in oxidation state form +2 to +3 is easiest?

Excess of KI reacts with ${\mathrm{CuSO}}_4$ solution and then ${\mathrm{Na}}_2{\mathrm{S}}_2{\mathrm{O}}_3$ solution is added to it. Which of the statements is incorrect for this reaction?