The key difference between Latimer diagram and Frost diagram is that Latimer diagram summarizes the standard electrode potentials of a chemical element whereas Frost diagram summarizes the relative stability of different oxidation states of a substance.
Latimer diagram and Frost diagram are basically important in showing details about redox reactions. Moreover, these diagrams were named after the scientists who originally created them; Latimer diagram got its name from Wendell Mitchell Latimer while Frost diagram was named after Arthur Atwater Frost.
CONTENTS
1. Overview and Key Difference
2. What is Latimer Diagram
3. What is Frost Diagram
4. Side by Side Comparison – Latimer Diagram vs Frost Diagram in Tabular Form
5. Summary
What is Latimer Diagram?
Latimer diagram is a summary of the standard electrode potentials of an element. The diagram is named after the American Chemist Wendell Mitchell Latimer. When constructing this kind of diagrams, we should write the highly oxidized form of the chemical element on the left side. Then we can write the oxidation states in descending order to the left – the left corner will have the least oxidation state. Between these oxidation states, we use an arrow (arrowhead to the left). Moreover, on the top of the arrow, we have to write the standard electrode potential for the reaction of conversion of the oxidation state on the right side to the left side. For example,
Figure 01: A Latimer Diagram Showing the Different Oxidation States of Oxygen Atom
The chemical element we considered in the above example is oxygen. It has the following chemical species with corresponding oxidation states of oxygen:
- O2 – oxidation state is zero
- H2O2 – oxidation state of oxygen is -1
- H2O – oxidation state of oxygen is -2
The Latimer diagram is important in constructing Frost diagram since we can obtain electrode potential of non-adjacent steps of a reaction that is necessary for the development of Frost diagram. Moreover, it is important in indicating whether a certain chemical species undergo deprotonation under the conditions at which the electrode potential is given.
What is Frost Diagram?
Frost diagram is an illustration that shows the relative stability of different oxidation states of a substance. It is important in inorganic chemistry and electrochemistry. Furthermore, it is a graph, and it has the oxidation state at the x-axis and the free energy at the y-axis. Here, the graph depends on the pH. Therefore we need to include the pH at which we take measurements. We can determine the free energy using oxidation-reduction half-reactions. Moreover, we can determine the reduction potentials easily using this diagram rather than using a Latimer diagram.
Figure 02: A Frost Diagram
When constructing the diagram, we need to mark the oxidation state at the x-axis and the free energy at the y-axis with zero in the middle. Because, the free energy has both negative and positive values. Furthermore, the slope of the graph shows the standard electrode potential between the two oxidation states.
What is the Difference Between Latimer Diagram and Frost Diagram?
Latimer diagram and Frost diagram are important in determining information about oxidation and reduction in redox reactions. However, the key difference between Latimer diagram and Frost diagram is that the Latimer diagram summarizes the standard electrode potentials of a chemical element, but the Frost diagram summarizes the relative stability of different oxidation states of a substance.
Below infographic summarizes the difference between Latimer diagram and Frost diagram in tabular form.
Summary – Latimer Diagram vs Frost Diagram
Overall, Latimer diagram and Frost diagram help us to determine information about oxidation and reduction in redox reactions. But, the key difference between Latimer diagram and Frost diagram is that the Latimer diagram summarizes the standard electrode potentials of a chemical element, whereas the Frost diagram summarizes the relative stability of different oxidation states of a substance.
Reference:
1. “Diagrams Used in Redox Chemistry. ” Western Oregon University, Available here.
2. “4.3: Latimer and Frost Diagrams.” Chemistry LibreTexts, Libretexts, 5 June 2019, Available here.
Image Courtesy:
1. “Latimerdiagram zuurstof” By Dr.T – Own work (CC BY-SA 3.0) via Commons Wikimedia
2. “Frost Diagram” By Jlange1125 – I made the diagram in excel (CC BY-SA 3.0) via Commons Wikimedia
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