Electrochemistry: The study of production of electrical energy from power released during spontaneous chemical reactions, and also the use of electric energy to bring about non-spontaneous chemical revolutions is called electrochemistry.

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Electrochemical Cell: A an equipment which can use chemical energy to generate electric energy, or can use electrical energy to reason chemical reaction is dubbed electrochemical cell. There space two types of electrochemical cell, viz. Galvanic cell and electrolytic cell.

Galvanic Cell: The electrochemical cabinet which uses chemical energy to create electrical power is referred to as galvanic cabinet or voltaic cell, e.g. Daniell Cell.

Electrolytic Cell: The electrochemical cabinet which uses electrical energy to reason chemical reactions is called electrolytic cell.

Daniell Cell

It has a zinc fifty percent cell and a copper fifty percent cell. The zinc half cell has zinc sulphate solution, when the copper fifty percent cell consists of copper sulphate solution; as electrolyte. A salt bridge connects both the half cells in order to finish the circuit.


The two half reactions which occur in Daniell cell room as follows:

Reduction fifty percent Reaction: `Cu^(2+)+2e^(-)→Cu(s)`

Oxidation fifty percent Reaction: `Zn(s)→Zn^(2+)+2e^-`

The all at once redox reaction in a Daniell Cell can be created as follows:

`Zn(s) + Cu^(2+)(aq) ``→Zn^(2+)(aq) + Cu(s)`

Cathode: The fifty percent cell in which reduction reaction takes ar is dubbed cathode.

Anode: The half cell in i beg your pardon oxidation reaction takes ar is called anode.

Electrode Potential

The potential difference in between the electrode and electrolyte is called electrode potential. At every electrode-electrolyte interface, over there is propensity of steel ions (from the solution) come deposit on the steel electrode; do the efforts to make it positive charged. Similarly, steel atoms that the electrode have actually a propensity to enter the solution as ions, and also leave behind the electron at the electrode; make the efforts to make it negatively charged. As soon as concentrations of all the species involved in half-cell is unity then the electrode potential is called standard electrode potential.

Cell Potential: The potential difference between two electrodes of a galvanic cell is called cell potential. When no current is drawn through the cell, then cell potential is referred to as electromotive force (emf). Together per convention, emf that the cabinet is positive, and it is given by potential that the fifty percent cell on RHS (cathode) minus the potential of the half cell ~ above LHS (anode).

Ecell = Eright - Eleft

This deserve to be presented by following example:

Cell Reaction: `Cu(s) + 2Ag^+(aq)``→Cu^(2+)(aq)+2Ag(s)` ………(1)

Cathode (Reduction): `2Ag^+(aq)+2e^(-)→2Ag(s)` ………………(2)

Anode (Oxidation): `Cu(s)→Cu^(2+)(aq)+2e^-` ...............(3)

Now, emf because that this cell can be provided as follows:

Ecell = Eright - Eleft = EAg+|Ag - ECu2+|Cu

Measurement the Electrode Potential:

It is not possible to measure up the potential that individual half cell. We have the right to only measure up the difference in between the two half cell potentials. This measurement gives the emf the the cell.

According come convention, a half cell called standard hydrogen electrode is assigned a zero potential at all temperatures equivalent to adhering to reaction.


Standard Hydrogen Electrode: It is composed of a platinum electrode coated which is coated v platinum black. This electrode is dipped in acidic solution and pure hydrogen gas is bubbled through the solution. The concentration of both the reduced and oxidized develops of hydrogen is kept at unity. This way that the pressure of hydrogen gas is 1 bar and concentration that hydrogen ion in the equipment is 1 molar.

At 298 K, the emf that the cell offers the reduction potential of the other fifty percent cell. This cabinet is created by taking conventional hydrogen electrode as anode and also the other half cell as cathode. If the concentration of the oxidized and reduced develops of the species in the right hand fifty percent cell are unity, the cell potential is equal to traditional electrode potential (`E_R^Θ`)of the given fifty percent cell.

`E^Θ= E_R^Θ- E_L^Θ`

Since `E_L^Θ` for standard hydrogen electrode is zero

Hence, `E^Θ= E_R^Θ`

The measured emf the the cabinet (containing Cu as cathode) is 0.34 V i beg your pardon is also the worth for the standard electrode potential the the fifty percent cell corresponding to complying with reaction.


Similarly, the measure emf the the cabinet (containing Zn as cathode) is -0.76V i m sorry is likewise the worth for typical electrode potential the the fifty percent cell matching to adhering to reaction.

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The hopeful value of conventional potential in the very first case shows that Cu2+ ions het reduced an ext easily than H+ ions. The an unfavorable value in the second case mirrors that H+ ions have the right to oxidise zinc (or zinc have the right to reduce hydrogen ions).

In paper definition of this convention, the half reaction because that Daniell Cell can be created as follows: