Electrochemistry

#folder

This is a galvanic cell battery


Anode Cathode
Oxidation Reduction
Lose electrons Gain electrons
Lower potential Higher potential

There's also an electrolytic cell battery, where the anode and cathode are flipped.

Summary

  • Oxidation reaction: substance looses electrons
    • Reducing agent (reductant): donates electrons, is oxidized
  • Reduction reaction: substance gains electrons
    • Oxidizing agent (oxidant): accepts electrons, is reduced

Note sometimes we move the to the other side:

are equivalent.

Cathode reaction, anode reaction, add cathode reaction and reversed anode reaction to get overall reaction.

Oxidation and Reduction Reactions

Info

For every oxidation reaction, a reduction reaction occurs and vice versa

Oxidation Reactions

Definition

An oxidation reaction is one of the following:

  • A substance reacts directly with oxygen, or
  • A substance reacts with another and loses hydrogen, or
  • A substance looses electrons
Example

reacts with to form sodium oxide

Example


loses hydrogen and just becomes

Example


looses electrons and becomes , so it oxidizes. is known as the reducing agent.

Reduction Reactions

Definition

Reverse of an oxidation reaction, a reduction reaction is one of the following:

  • A substance loses oxygen atoms, or
  • A substance reacts with another and gains hydrogen, or
  • A substance gains electrons
Example

loses oxygen and becomes

Example


gains electrons and becomes , so it reduces. is known as the oxidizing agent.

Redox Reactions

Definition

Reactions involving oxidation and reduction are known as redox reactions. Redox reactions involve electron transfer.

Example

  • looses electrons and becomes , so it oxidizes (reducing agent)
  • gains electrons and becomes , so it reduces (oxidizing agent)
Example

Note that the superscripts are oxidation numbers, not charge.

  • , lost 2 electrons, oxidation
  • , gained 1 electron, reduction
Important

If a substance is aqueous, it's in its ionic form

Agents

Definition

The oxidizing agent (oxidant) is the electron acceptor, because it is reduced
The reducing agent (reductant) is the electron donor, because it is oxidized

Example

  • is the oxidizing agent, because it is reduced to
  • is the reducing agent, because it is oxidized to