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Redox and ionic equations: identification skills

Chemical changes • Reactivity of metals

Key concepts

What you'll likely be quizzed about

  • Oxidation is when an atom, ion, or molecule loses electrons, causing an increase in oxidation state.
  • Reduction is the process of gaining electrons, resulting in a decrease in oxidation state.
  • Tracking electron flow and changes in oxidation numbers is essential for clear identification.
  • Oxidation and reduction occur simultaneously in a redox reaction, as the electrons lost by the oxidised species are transferred to the reduced species.
  • Balanced electron transfer in half-equations ensures conservation of charge.

Flashcards

Test your knowledge with interactive flashcards

State the role of electrons in half-equations.

Click to reveal answer

Electrons indicate the transfer of charge and must balance between oxidation and reduction half-equations.

Key notes

Important points to keep in mind

Oxidation = loss of electrons; reduction = gain of electrons.

Assign oxidation numbers to identify changes; compare before and after reaction.

Write half-equations to show electron transfer explicitly.

Multiply half-equations to equalise electrons before combining.

Remove spectator ions to produce the ionic equation.

Include state symbols to decide which species dissociate into ions.

In displacement, the more reactive metal is oxidised and the less reactive metal ion is reduced.

Check both mass and charge balance in the final equation.

Disproportionation occurs when one species is both oxidised and reduced.

Use H+, H2O (acid) or OH-, H2O (alkali) to balance oxygen and hydrogen in half-equations.

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