Electrochemistry
Advanced & Detailed Notes
Electrochemistry is a major branch of physical chemistry that studies the
relationship between chemical reactions and electrical energy, especially reactions
involving the transfer of electrons.
It is important in chemistry, biology, medicine, engineering, batteries, corrosion
science, electroplating, sensors, and energy technology.
1. Basic Idea of
Electrochemistry
Electrochemistry is based mainly on red-ox reactions.
A red-ox reaction has two processes occurring together:
Oxidation → loss of electrons
Reduction → gain of electrons
For example:
Zn+Cu2+→Zn2++Cu
Here:
Zn→Zn2++2e−
is oxidation.
And:
Cu2++2e−→Cu
is reduction.
The electrons released by zinc are accepted by copper ions.
, 2. Oxidizing and Reducing
Agents
Oxidizing Agent
An oxidizing agent causes another substance to be oxidized and itself undergoes
reduction.
In:
Zn+Cu2+→Zn2++Cu
Cu2+ is the oxidizing agent.
Reducing Agent
A reducing agent causes another substance to be reduced and itself undergoes
oxidation.
Here, zinc is the reducing agent.
Important Rule
The oxidizing agent is reduced, while the reducing
agent is oxidized.
3. Half-Reactions
A red-ox reaction can be separated into two half-reactions.
For the zinc-copper reaction:
Oxidation half reaction
Zn(s)→Zn2+(aq)+2e−
Reduction half-reaction
Cu2+(aq)+2e−→Cu(s)
Adding them gives:
Zn+Cu2+→Zn2++Cu
Advanced & Detailed Notes
Electrochemistry is a major branch of physical chemistry that studies the
relationship between chemical reactions and electrical energy, especially reactions
involving the transfer of electrons.
It is important in chemistry, biology, medicine, engineering, batteries, corrosion
science, electroplating, sensors, and energy technology.
1. Basic Idea of
Electrochemistry
Electrochemistry is based mainly on red-ox reactions.
A red-ox reaction has two processes occurring together:
Oxidation → loss of electrons
Reduction → gain of electrons
For example:
Zn+Cu2+→Zn2++Cu
Here:
Zn→Zn2++2e−
is oxidation.
And:
Cu2++2e−→Cu
is reduction.
The electrons released by zinc are accepted by copper ions.
, 2. Oxidizing and Reducing
Agents
Oxidizing Agent
An oxidizing agent causes another substance to be oxidized and itself undergoes
reduction.
In:
Zn+Cu2+→Zn2++Cu
Cu2+ is the oxidizing agent.
Reducing Agent
A reducing agent causes another substance to be reduced and itself undergoes
oxidation.
Here, zinc is the reducing agent.
Important Rule
The oxidizing agent is reduced, while the reducing
agent is oxidized.
3. Half-Reactions
A red-ox reaction can be separated into two half-reactions.
For the zinc-copper reaction:
Oxidation half reaction
Zn(s)→Zn2+(aq)+2e−
Reduction half-reaction
Cu2+(aq)+2e−→Cu(s)
Adding them gives:
Zn+Cu2+→Zn2++Cu
