The quantity of electricity required to liberate $112\,cc$ of hydrogen at STP from acidified water is
- 965 C
- 4825 C
- 9650 C
- 96500 C
The Correct Option is A
Solution and Explanation
${1 \, mole\, of\, H_2 = 2}$ Faradays of electricity
${22490\, cc\, of\, H_ 2 = 2 \times 96500\, C}$
${ 112 \, cc \, of \, H_2 = \frac{2 \times 96500}{22400} \times 112}$
= 965 C of electricity
Top Questions on Electrochemistry
- The correct statement/s about Galvanic cell is/are:
(a) Current flows from cathode to anode
(b) Anode is positive terminal
(c) If \(E_{\text{cell}} < 0\), then it is spontaneous reaction
(d) Cathode is positive terminal- KCET - 2025
- Chemistry
- Electrochemistry
- In an electrochemical cell, the standard electrode potential of \( \text{Zn}^{2+}/\text{Zn} \) is \( -0.76 \, \text{V} \) and that of \( \text{Cu}^{2+}/\text{Cu} \) is \( +0.34 \, \text{V} \). What is the standard EMF of the cell formed by these electrodes?
- MHT CET - 2025
- Chemistry
- Electrochemistry
- What is the standard electrode potential of the half-reaction: \[ \text{Cu}^{2+} + 2e^- \rightarrow \text{Cu} \, (\text{solid})? \] Given that the standard electrode potential for the half-reaction: \[ \text{Ag}^+ + e^- \rightarrow \text{Ag} \, (\text{solid}) \quad \text{is} \, +0.80 \, \text{V}. \] Also, the cell potential for the following reaction is: \[ \text{Cu}^{2+} + 2\text{Ag} \rightarrow \text{Cu} + 2\text{Ag}^+ \] is \( 0.46 \, \text{V} \).
- MHT CET - 2025
- Chemistry
- Electrochemistry
- What is the standard electrode potential for the reduction half-reaction \( \text{Cu}^{2+} + 2e^- \rightarrow \text{Cu} \)?
- MHT CET - 2025
- Chemistry
- Electrochemistry
Consider the following half cell reaction $ \text{Cr}_2\text{O}_7^{2-} (\text{aq}) + 6\text{e}^- + 14\text{H}^+ (\text{aq}) \longrightarrow 2\text{Cr}^{3+} (\text{aq}) + 7\text{H}_2\text{O}(1) $
The reaction was conducted with the ratio of $\frac{[\text{Cr}^{3+}]^2}{[\text{Cr}_2\text{O}_7^{2-}]} = 10^{-6}$
The pH value at which the EMF of the half cell will become zero is ____ (nearest integer value)
[Given : standard half cell reduction potential $\text{E}^\circ_{\text{Cr}_2\text{O}_7^{2-}, \text{H}^+/\text{Cr}^{3+}} = 1.33\text{V}, \quad \frac{2.303\text{RT}}{\text{F}} = 0.059\text{V}$- JEE Main - 2025
- Chemistry
- Electrochemistry
Questions Asked in KCET exam
A convex lens has power \( P \). It is cut into two halves along its principal axis. Further, one piece (out of two halves) is cut into two halves perpendicular to the principal axis as shown in the figure. Choose the incorrect option for the reported lens pieces.
- KCET - 2025
- Optics
The equation \[ 2 \cos^{-1} x = \sin^{-1} \left( 2 \sqrt{1 - x^2} \right) \] is valid for all values of \(x\) satisfying:
- KCET - 2025
- Inverse Trigonometric Functions
A metallic sphere of radius \( R \) carrying a charge \( q \) is kept at a certain distance from another metallic sphere of radius \( R_4 \) carrying a charge \( Q \). What is the electric flux at any point inside the metallic sphere of radius \( R \) due to the sphere of radius \( R_4 \)?
- KCET - 2025
- Electric Flux
- 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
The circuit shown in the figure contains two ideal diodes \( D_1 \) and \( D_2 \). If a cell of emf 3V and negligible internal resistance is connected as shown, then the current through \( 70 \, \Omega \) resistance (in amperes) is:
- KCET - 2025
- Refractive index
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.