Latimer and Frost Diagrams
Graphical summaries of reduction potentials across oxidation states.
Practise Acids, Bases & Electrochemistry All Acids, Bases & Electrochemistry topics
Graphical summaries of reduction potentials across oxidation states.
Practise Acids, Bases & Electrochemistry All Acids, Bases & Electrochemistry topics
Latimer diagrams list the standard reduction potentials between successive oxidation states of an element in a single line, giving a compact summary of its redox chemistry. Frost diagrams plot n times the standard potential against the oxidation number, so that the free energies of the species can be compared directly. A species that lies above the straight line joining its two neighbours on a Frost diagram is unstable toward disproportionation, while one lying below is stable. These diagrams make the stability of intermediate oxidation states easy to judge. They are widely used in inorganic chemistry.
Key ideas: Latimer diagram: oxidation states in order, with E standard (V) written over the arrows between neighbors. Frost diagram: plot of n E standard (volts times electrons, effectively delta G/F) against oxidation number. Species low on the plot are stable; one lying above the line joining its neighbors disproportionates; steep upward slope indicates a strong oxidizer.
Common mistakes and connections: Mistakes: reading E values reversed across a direction or forgetting that nonadjacent potentials combine by weighting electrons: E(1 to 3) = (n1E1 + n2E2)/(n1+n2), not a simple sum. Diagrams apply at a stated pH, so acid and base versions differ. Used for Mn, Cl, N and Cr chemistry.
A Frost diagram of manganese: species low on the plot are stable, so Mn2+ is the minimum, while MnO4- sits high and is a powerful oxidizer. The interactive lesson shows this as a live animation or chart.
A species lying above the line joining its neighbours on a Frost diagram will disproportionate into those neighbouring oxidation states.
Graphical summaries of reduction potentials across oxidation states.
Latimer and Frost Diagrams is a advanced topic in Acids, Bases & Electrochemistry. It builds on beginner and intermediate topics, so review those first if needed.
Study these earlier topics in Acids, Bases & Electrochemistry first: Activity and Activity Coefficients, Overpotential, Pourbaix Diagram.
The next topics in Acids, Bases & Electrochemistry are Ion-Selective Electrodes and pH Meter.
Yes. The interactive lesson includes a self-check question on Latimer and Frost Diagrams, and the Acids, Bases & Electrochemistry quiz draws on every topic in this area.
Latimer and Frost Diagrams is topic 91 of 105 in Acids, Bases & Electrochemistry.