Dr. K. Rajender Reddy gave a lecture on electrochemistry that covered several topics: 1) Electrode potential is the tendency of a metal to lose or gain electrons when in contact with a solution of its own salt. Zn undergoes oxidation in ZnSO4 by releasing electrons, while Cu undergoes reduction in CuSO4 as copper ions are deposited. 2) The standard electrode potential is measured at 25°C with a 1M electrolyte concentration and represents the potential of an oxidation or reduction reaction. 3) The electrochemical series arranges electrodes in order of increasing standard reduction potentials, ranging from the strongest reducing agent Li to the strongest oxidizing agent F.

1. Dr. K. RAJENDER REDDY
LECTURER IN CHEMISTRY
Email:raj3iict@gmail.com
Friday, April 24, 2020 1ELECTRO CHEMISTRY- KRR

2. Electrochemistry
(Electrode Potential, Electro
chemical series)
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3. Electrode potential
• The tendency of a metal to lose the electrons (oxidation) or gain the
electrons (reduction), when it is in contact with solution of its own salt is
called electrode potential.
• When a metal [M] is placed in a solution containing its own ions [Mn+],
then the metal may undergo either oxidation or reduction. If the metal
undergoes oxidation, then the positive metal ions may pass into the
solution
• M Mn+ + ne‒
• If the metal undergoes reduction, then the negative ions may get
deposited over the metal.
• Mn+ + ne‒ M
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4. Zn in ZnSO4
When Zn is placed in a solution of its own salt,
zinc undergoes oxidation with the release of
electrons. The electrons liberated in the
process, accumulate over the surface of the
metal and hence, the metal is negatively
charged. Now, the negatively charged metal
attracts the positive ions from the solution, and
hence formation of a double layer takes place
near the surface of the metal.
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5. Cu in CuSO4
When Cu is placed in the solution of CuSO4,
the copper ions in the solution gets
deposited over the metal and hence the
metal becomes positively charged. The
positively charged metal attracts the
negatively charged sulphate ions in the
solution and hence a doubly charged layer is
formed near the metal.
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6. Standard Electrode Potential
• Standard Electrode Potential: The potential of
an electrode at 25 oC with 1 M concentration
of electrolyte is called standard electrode
potential (E0).
Oxidation potential = - Reduction potential
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7. MEASURING OF ELECTRODE POTENTIAL
• It is not possible to determine experimentally
the potential of a single electrode, We can
only measure the potential difference
between two electrodes potentiometrically. In
order to measure the electrode potential, NHE
is taken as primary reference electrode
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8. Standard hydrogen electrode(SHE)
It contains 1 M HCl in a vessel
In which Pt plate is partially
dipped act as conductor
hydrogen gas at 1 atm
pressure bubbled into the
solution at 25 oC. The
potential Of NHE arbitrarily
taken as zero,
It is represented as Pt, H2 (1
atm)/ H+
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9. Electrochemical Series
• Electrochemical Series: The arrangement of
electrodes in the increasing order of their
standard reduction potentials is called
electrochemical series.
• In this top electrode is Li and the bottom
electrode is Fluorine
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10. Significance of electro chemical series
 The metal which is higher in electrochemical
series acts as reducing agent or anode and
undergoes corrosion first.
 Metals above hydrogen are called active
metals, which can displace hydrogen from
dilute acids or water.
 The metals below hydrogen are less reactive .
They do not liberate Hydrogen from dilute
acids or water
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11. Significance of electro chemical series
• The metal with higher negative potential
displace a metal with lower negative potential
or positive potential from the salt solution of
metal.
• The reactivity or reducing character decreases
From top to bottom, So Li is the strongest
reducing agent and fluorine is the strongest
oxidizing agent.
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12. Electro chemical series
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13. THANK U
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