For hydrogen - oxygen fuel cell at one $atm$ and $298\, K$
$H_2(g)+\frac {1}{2} O_2(g) \to H_2O_{(l)} ; \Delta G^\circ=-240\, kJ$
$E^\circ$ for the cell is approximately, (Given $F \,= \,96,500 \,C$)
- $1.25 \,V$
- $1.26 \,V$
- $2.48\, V$
- $2.5\, V$
The Correct Option is A
Solution and Explanation
where, $n=$ number of moles of electrons
transferred $=2$
$\Rightarrow F=96500\, C$
$\Delta G^{\circ}=-240\, kJ =-240 \times 1000\, J$
$\therefore E^{\circ}=\frac{-240000}{-2 \times 96500}=1.24\, V$
Top Questions on Electrochemistry
- Explain in brief the Faraday's laws of Electrolysis. CuSO$_4$ solution was electrolysed for 20 minutes with 2.0 ampere current. What will be the mass of precipitated copper at cathode?
- UP Board XII - 2025
- Chemistry
- Electrochemistry
Standard electrode potential for \( \text{Sn}^{4+}/\text{Sn}^{2+} \) couple is +0.15 V and that for the \( \text{Cr}^{3+}/\text{Cr} \) couple is -0.74 V. The two couples in their standard states are connected to make a cell. The cell potential will be:
To calculate the cell potential (\( E^\circ_{\text{cell}} \)), we use the standard electrode potentials of the given redox couples.
Given data:
\( E^\circ_{\text{Sn}^{4+}/\text{Sn}^{2+}} = +0.15V \)
\( E^\circ_{\text{Cr}^{3+}/\text{Cr}} = -0.74V \)- CBSE CLASS XII - 2025
- Chemistry
- Electrochemistry
- The standard reduction potentials are: \[ \mathrm{Cu^{2+} + 2e^- \rightarrow Cu} \quad E^\circ = +0.34\,V \] \[ \mathrm{Zn^{2+} + 2e^- \rightarrow Zn} \quad E^\circ = -0.76\,V \] Calculate the standard cell potential for the reaction: \[ \mathrm{Zn + Cu^{2+} \rightarrow Zn^{2+} + Cu} \]
- BITSAT - 2025
- Chemistry
- Electrochemistry
- The standard electrode potential for Sn\(^{4+}\)/Sn\(^{2+}\) couple is \(+0.15\ \text{V}\) and for Cu\(^{2+}\)/Cu couple is \(+0.73\ \text{V}\). These two couples are connected to make an electrochemical cell. The redox reaction is spontaneous. The cell potential will be:
- CBSE Compartment XII - 2025
- Chemistry
- Electrochemistry
- Which metal reacts most with dilute acid to displace hydrogen?
- AIIMS Paramedical - 2025
- Chemistry
- Electrochemistry
Questions Asked in KCET exam
A block of certain mass is placed on a rough floor. The coefficients of static and kinetic friction between the block and the floor are 0.4 and 0.25 respectively. A constant horizontal force \( F = 20 \, \text{N} \) acts on it so that the velocity of the block varies with time according to the following graph. The mass of the block is nearly (Take \( g = 10 \, \text{m/s}^2 \)):
- KCET - 2025
- work, energy and power
- Given, a current carrying wire of non-uniform cross-section, which of the following is constant throughout the length of the wire?
- KCET - 2025
- Current electricity
- If the number of terms in the binomial expansion of \((2x + 3)^n\) is 22, then the value of \(n\) is:
- KCET - 2025
- Binomial theorem
- Ethyl alcohol is heated with concentrated sulphuric acid at 413 K (140°C). The major product formed is
- KCET - 2025
- Organic Chemistry
- A body of mass 0.25 kg travels along a straight line from \( x = 0 \) to \( x = 2 \, \text{m} \) with a speed \( v = k x^2 \) where \( k = 2 \, \text{m}^{-1} \). The work done by the net force during this displacement is
- KCET - 2025
- Elastic and inelastic collisions
Concepts Used:
Electrochemical Cells
An electrochemical cell is a device that is used to create electrical energy through the chemical reactions which are involved in it. The electrical energy supplied to electrochemical cells is used to smooth the chemical reactions. In the electrochemical cell, the involved devices have the ability to convert the chemical energy to electrical energy or vice-versa.
Classification of Electrochemical Cell:
Cathode
- Denoted by a positive sign since electrons are consumed here
- A reduction reaction occurs in the cathode of an electrochemical cell
- Electrons move into the cathode
Anode
- Denoted by a negative sign since electrons are liberated here
- An oxidation reaction occurs here
- Electrons move out of the anode
Types of Electrochemical Cells:
Galvanic cells (also known as Voltaic cells)
- Chemical energy is transformed into electrical energy.
- The redox reactions are spontaneous in nature.
- The anode is negatively charged and the cathode is positively charged.
- The electrons originate from the species that undergo oxidation.
Electrolytic cells
- Electrical energy is transformed into chemical energy.
- The redox reactions are non-spontaneous.
- These cells are positively charged anode and negatively charged cathode.
- Electrons originate from an external source.