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American Journal of Public Health Research
DOI: 10.12691/ajphr-1-1-3

The Implementation of a Tele-Homecare System with Service Oriented Architecture and HL7 Message Transmission Standard
Ching-Sung Wang

American Journal of Medical and Biological Research
DOI: 10.12691/ajmbr-1-1-2

The Influence of Ethanol on Pyruvate Kinases Activity in Vivo, in Vitro, in Silico
Lelevich Sergey Vladimirovich, Khrustalev Vladislav Victorovich, Barkovsky Eugene Victorovich, Shedogubova Tatyana Aleksandrovna

American Journal of Medical Sciences and Medicine
DOI: 10.12691/ajmsm-1-1-1

Clinical and Histological Features in Wegener Granulomatosis
Li Cavoli Gioacchino, Passantino Rita, Bono Luisa, Tortorici Calogera, Ferrantelli Angelo, Giammarresi Carlo, Rotolo Ugo

American Journal of Infectious Diseases and Microbiology
DOI: 10.12691/ajidm-1-1-2

The Curse of Lymphatic Filariasis: Would the Continual Use of Diethylcarbamazine Eliminate this Scourge in Papua New Guinea?
Anne Lanham, Lillian Mwanri

We have released issues of some journals on February 2013.
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Label_Title

Dear Label_Name,

Greetings! I hope you are well.

I am writing on behalf of an international publishing house, Science and Education Publishing, USA (http://www.sciepub.com).

Science and Education Publishing (SciEP) is a multidisciplinary open access publisher of Journals covering the fields of Science, Technology and Medicine. All SciEP publications are subject to high-quality peer review, editorial and production processes and are freely available online.

Welcome to the April, 2013 edition of SciEP newsletter, providing monthly summaries of articles on science & education related topics of interest to scientist and professionals. The mission of our journals is to provide an open access forum for publishing new findings on issues pertinent to scientific and academic field. We also invite you to submit original research papers, review articles, short reports, or case studies are considered for publication in our Multidisciplinary Journals.

American Journal of Public Health Research
DOI: 10.12691/ajphr-1-1-3

The Implementation of a Tele-Homecare System with Service Oriented Architecture and HL7 Message Transmission Standard
Ching-Sung Wang

American Journal of Medical and Biological Research
DOI: 10.12691/ajmbr-1-1-2

The Influence of Ethanol on Pyruvate Kinases Activity in Vivo, in Vitro, in Silico
Lelevich Sergey Vladimirovich, Khrustalev Vladislav Victorovich, Barkovsky Eugene Victorovich, Shedogubova Tatyana Aleksandrovna

American Journal of Medical Sciences and Medicine
DOI: 10.12691/ajmsm-1-1-1

Clinical and Histological Features in Wegener Granulomatosis
Li Cavoli Gioacchino, Passantino Rita, Bono Luisa, Tortorici Calogera, Ferrantelli Angelo, Giammarresi Carlo, Rotolo Ugo

American Journal of Infectious Diseases and Microbiology
DOI: 10.12691/ajidm-1-1-2

The Curse of Lymphatic Filariasis: Would the Continual Use of Diethylcarbamazine Eliminate this Scourge in Papua New Guinea?
Anne Lanham, Lillian Mwanri

We have released issues of some journals on February 2013.
American Journal of Public Health Research
American Journal of Medical Sciences and Medicine
American Journal of Medical and Biological Research
American Journal of Pharmacological Sciences
American Journal of Clinical Medicine Research
American Journal of Nursing Research
American Journal of Cancer Prevention
American Journal of Medicine Studies
American Journal of Infectious Diseases and Microbiology
American Journal of Cardiovascular Disease Research
American Journal of Biomedical Research
American Journal of Mechanical Engineering
American Journal of Microbiological Research
Journal of Preventive Medicine
American Journal of Food and Nutrition
American Journal of Hypertension Research
American Journal of Sports Science and Medicine
Journal of Cancer Research and Treatment
American Journal of Zoological Research
Journal of Biomedical Engineering and Technology
American Journal of Microbiological Research
Biomedical Science and Engineering

We are pleased to announce that submissions are now being accepted for peer review for all the journals across all our subject areas in SciEP.

Please submit your manuscript via our online submission system:
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Label_Title

Dear Label_Name,

Greetings! I hope you are well.

I am writing on behalf of an international publishing house, Science and Education Publishing, USA (http://www.sciepub.com).

Science and Education Publishing (SciEP) is a multidisciplinary open access publisher of Journals covering the fields of Science, Technology and Medicine. All SciEP publications are subject to high-quality peer review, editorial and production processes and are freely available online.

Welcome to the April, 2013 edition of SciEP newsletter, providing monthly summaries of articles on science & education related topics of interest to scientist and professionals. The mission of our journals is to provide an open access forum for publishing new findings on issues pertinent to scientific and academic field. We also invite you to submit original research papers, review articles, short reports, or case studies are considered for publication in our Multidisciplinary Journals.

American Journal of Public Health Research
DOI: 10.12691/ajphr-1-1-3

The Implementation of a Tele-Homecare System with Service Oriented Architecture and HL7 Message Transmission Standard
Ching-Sung Wang

American Journal of Medical and Biological Research
DOI: 10.12691/ajmbr-1-1-2

The Influence of Ethanol on Pyruvate Kinases Activity in Vivo, in Vitro, in Silico
Lelevich Sergey Vladimirovich, Khrustalev Vladislav Victorovich, Barkovsky Eugene Victorovich, Shedogubova Tatyana Aleksandrovna

American Journal of Medical Sciences and Medicine
DOI: 10.12691/ajmsm-1-1-1

Clinical and Histological Features in Wegener Granulomatosis
Li Cavoli Gioacchino, Passantino Rita, Bono Luisa, Tortorici Calogera, Ferrantelli Angelo, Giammarresi Carlo, Rotolo Ugo

American Journal of Infectious Diseases and Microbiology
DOI: 10.12691/ajidm-1-1-2

The Curse of Lymphatic Filariasis: Would the Continual Use of Diethylcarbamazine Eliminate this Scourge in Papua New Guinea?
Anne Lanham, Lillian Mwanri

We have released issues of some journals on February 2013.
American Journal of Public Health Research
American Journal of Medical Sciences and Medicine
American Journal of Medical and Biological Research
American Journal of Pharmacological Sciences
American Journal of Clinical Medicine Research
American Journal of Nursing Research
American Journal of Cancer Prevention
American Journal of Medicine Studies
American Journal of Infectious Diseases and Microbiology
American Journal of Cardiovascular Disease Research
American Journal of Biomedical Research
American Journal of Mechanical Engineering
American Journal of Microbiological Research
Journal of Preventive Medicine
American Journal of Food and Nutrition
American Journal of Hypertension Research
American Journal of Sports Science and Medicine
Journal of Cancer Research and Treatment
American Journal of Zoological Research
Journal of Biomedical Engineering and Technology
American Journal of Microbiological Research
Biomedical Science and Engineering

We are pleased to announce that submissions are now being accepted for peer review for all the journals across all our subject areas in SciEP.

Please submit your manuscript via our online submission system:
http://www.sciepub.com/author/signin

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Label_Title

Dear Label_Name,

Greetings! I hope you are well.

I am writing on behalf of an international publishing house, Science and Education Publishing, USA (http://www.sciepub.com).

Science and Education Publishing (SciEP) is a multidisciplinary open access publisher of Journals covering the fields of Science, Technology and Medicine. All SciEP publications are subject to high-quality peer review, editorial and production processes and are freely available online.

Welcome to the April, 2013 edition of SciEP newsletter, providing monthly summaries of articles on science & education related topics of interest to scientist and professionals. The mission of our journals is to provide an open access forum for publishing new findings on issues pertinent to scientific and academic field. We also invite you to submit original research papers, review articles, short reports, or case studies are considered for publication in our Multidisciplinary Journals.

American Journal of Public Health Research
DOI: 10.12691/ajphr-1-1-3

The Implementation of a Tele-Homecare System with Service Oriented Architecture and HL7 Message Transmission Standard
Ching-Sung Wang

American Journal of Medical and Biological Research
DOI: 10.12691/ajmbr-1-1-2

The Influence of Ethanol on Pyruvate Kinases Activity in Vivo, in Vitro, in Silico
Lelevich Sergey Vladimirovich, Khrustalev Vladislav Victorovich, Barkovsky Eugene Victorovich, Shedogubova Tatyana Aleksandrovna

American Journal of Medical Sciences and Medicine
DOI: 10.12691/ajmsm-1-1-1

Clinical and Histological Features in Wegener Granulomatosis
Li Cavoli Gioacchino, Passantino Rita, Bono Luisa, Tortorici Calogera, Ferrantelli Angelo, Giammarresi Carlo, Rotolo Ugo

American Journal of Infectious Diseases and Microbiology
DOI: 10.12691/ajidm-1-1-2

The Curse of Lymphatic Filariasis: Would the Continual Use of Diethylcarbamazine Eliminate this Scourge in Papua New Guinea?
Anne Lanham, Lillian Mwanri

We have released issues of some journals on February 2013.
American Journal of Public Health Research
American Journal of Medical Sciences and Medicine
American Journal of Medical and Biological Research
American Journal of Pharmacological Sciences
American Journal of Clinical Medicine Research
American Journal of Nursing Research
American Journal of Cancer Prevention
American Journal of Medicine Studies
American Journal of Infectious Diseases and Microbiology
American Journal of Cardiovascular Disease Research
American Journal of Biomedical Research
American Journal of Mechanical Engineering
American Journal of Microbiological Research
Journal of Preventive Medicine
American Journal of Food and Nutrition
American Journal of Hypertension Research
American Journal of Sports Science and Medicine
Journal of Cancer Research and Treatment
American Journal of Zoological Research
Journal of Biomedical Engineering and Technology
American Journal of Microbiological Research
Biomedical Science and Engineering

We are pleased to announce that submissions are now being accepted for peer review for all the journals across all our subject areas in SciEP.

Please submit your manuscript via our online submission system:
http://www.sciepub.com/author/signin

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Some Applications of Latimer Diagrams in Teaching Oxidation-Reduction Reactions for Chemistry Students at Pedagogical Universities

Cao Cu Giac*, Cao Thi Van Giang

Vinh University, Vinh City, Vietnam

Abstract: In the training program for chemistry pedagogical students at pedagogical universities, knowledge of oxidation-reduction reactions is taught when students learn about the electrochemistry chapter belonging to the theory of chemical processes. There, students are introduced to how to use standard electrode potential values of oxidation/reduction pairs to predict the likelihood of an oxidation-reduction reaction. However, a common difficulty for students is predicting reaction products of substances containing elements with several oxidation states. To simplify this problem, using the Latimer diagram will help students be more interested in predicting the stable oxidation state of the element, calculating the standard reduction potential of oxidation-reduction pairs that are not close to each other and predict the products of many complex oxidation-reduction reactions.

Keywords: Latimer diagram, standard electrode potential, standard reduction potential, oxidation-reduction reactions, teaching chemistry

Received May 20, 2024; Revised June 21, 2024; Accepted June 28, 2024

Citation: Cao Cu Giac, Cao Thi Van Giang, Some Applications of Latimer Diagrams in Teaching Oxidation-Reduction Reactions for Chemistry Students at Pedagogical Universities. World Journal of Chemical Education, 12 (2). 49-59. January 2024. doi:10.12691/wjce-12-2-2

1. Introduction

1.1. Latimer Diagram

This is one of the potential data diagrams summarizing the relative thermodynamic stability of a series of compounds of the same element in different oxidation states [1,2,3,5]. The author of the diagram is Wendell Mitchell Latimer, an American chemist, one of the leaders in the application of thermodynamics in inorganic chemistry [13]. The Latimer diagram is a simple and convenient way to record the oxidation-reduction properties of an element representing many different oxidation numbers. From left to right, the elemental compounds are arranged in order of decreasing oxidation number [4] [6].

The diagram is denoted [1] [7] [8]:

Where:

Oxid and Red are the oxidized and reduced forms of the reduction half-reaction.

and is the oxidation number of the element.

Eo is the standard reduction potential of that half-reaction (unit is V).

Example:

The symbol:

means corresponding to the half-reaction:

The symbol:

means corresponding to the half-reaction:

In addition, based on Hess's law, we can establish a Latimer diagram to compare the standard reduction potentials of the reactants and products of the reaction, thereby making predictions about the favorable direction of the reaction.

1.2. Latimer Diagram of Some Elements

The electrode potential data are quoted from references [9,10,11,12] [13] [14].

Subgroup IA

Acidic solution:

Basic solution:

Subgroup IIA

Acidic solution:

Basic solution:

Subgroup IIIA

Acidic solution:

Basic solution:

Subgroup IVA

Acidic solution:

Basic solution:

Subgroup VA

Acidic solution:

Basic solution:

Subgroup VIA

Acidic solution:

Basic solution:

Subgroup VIIA

Acidic solution:

Basic solution:

Subgroup VIIIA

Acidic solution:

Basic solution:

Subgroup IB

Acidic solution:

Basic solution:

Subgroup IIB

Acidic solution:

Basic solution:

Subgroup VIB

Acidic solution:

Basic solution:

Subgroup VIIB

Acidic solution:

Basic solution:

Subgroup VIIIB

Acidic solution:

Basic solution:

1.3. Predict the Stable Oxidation State of the Element

Consider the two half-reactions side by side in the Latimer diagram:

• If > then half of the reaction of the B/C pair proceeds spontaneously in the forward direction and the other half A/B in the reverse direction → B is an unstable particle, it has the ability to self-oxidize-reduce to A (higher oxidation number) and C (lower oxidation number). That process is called disproportion.

• If < then half of the reaction of the B/C pair proceeds spontaneously in the reverse direction and the other half A/B in the forward direction → B is a stable particle, particle A (higher oxidation number) will react with particle C (lower oxidation number) to produce B (intermediate oxidation number). That process is called comproportion.

Note: The standard reduction potential written on the hyphen corresponds to the half-reaction going from left to right (forward direction). When writing in the reverse direction, pay attention to changing the sign of the standard reduction potential.

Example 1: From the Latimer diagram for oxygen (see subgroup VIA), we see that H₂O₂ is unstable in acidic solution and is disproportioned into H₂O and O₂.

The total reaction potential is quite positive, so the reaction is thermodynamically favorable. In fact, H₂O₂ decomposes immediately under normal conditions, but occurs at a very small rate, not clearly observed. When there is a catalyst or when heated or exposed to light, the reaction occurs very quickly, sometimes causing an explosion.

Example 2: From the Latimer diagram for iron (see subgroup VIIIB), we see , that is, Fe²⁺ is stable to disproportion, while Fe³⁺ and Fe undergo comproportion, that is, they will interact with each other to produce Fe²⁺. This result is confirmed, by calculating the sum of the following two half-reactions:

The total reaction potential is quite positive (+ 1.21V), so the comproportion occurs easily in aqueous solution.

1.4. Calculate the Standard Reduction Potential of Oxidation-Reduction Pairs that are Not Close to Each Other

Another application of the Latimer diagram is that from the diagram it is possible to calculate the standard reduction potential of oxidation-reduction pairs that are not close to each other. The calculation is based on the relationship betweenand Eo of the process and the reality is common of n successive processes is equal to the sumof n processes. For example, the Eo of the A/D pair can be calculated from the Latimer diagram as follows:

From the Latimer diagram of chlorine, we can write the half-reactions and reactions that need to determine the standard reduction potential:

Applying the above calculation we have:

1.5. Predict Reaction Products

A new application of the Latimer diagram is to be able to predict reaction products of substances containing elements with several oxidation states. Consider, for example, the reaction of iodide anion with permanganate in acidic solution. The Latimer diagrams of the relevant elements are as follows:

From the diagram above, we see that there are 3 unstable particles with disproportion: HIO, and Mn³⁺. In addition, Mn is not stable in acidic environments so there is no need to consider them. Therefore, the diagram is simplified as follows:

If permanganate ( ) is added drop by drop to a hydroiodic acid solution HI (excess I⁻), then the reaction product needs to be compatible with the presence of iodide ion. Therefore iodate () cannot form, because it will react with I- to form ion (comproportion). Similarly, MnO₂ does not form because it has the ability to oxidize I⁻. It follows that the total reaction must be:

Conversely, if iodide solution is added drop by drop to an acidified permanganate solution (excess ), the reaction product must be consistent with the presence of . Therefore, Mn²⁺ ion cannot form because it will react with the ion to produce MnO₂ (comproportion). Then I⁻ will not be completely oxidized to the ion because the ion has the ability to reduce ion. The fact that the H₅IO₆-and -MnO₂ half-reactions are potentially equal (+ 1.70 V) further complicates the problem. Therefore, we see that I⁻ ion is not completely oxidized to or periodic acid (H₅IO₆) but to a mixture of products:

Note that changing the excess reactants can lead to different products.

In addition to the Latimer diagram, we also use the Pourbaix (Frost-Ebsworth) diagram to consider the general relationship between oxidation-reduction activity and Bronsted acid-base activity.

The Pourbaix diagram, also known as the E-pH diagram, is a graphical tool used to predict the stability of different oxidation forms of an element in solution. This chart is built based on two main factors:

Oxidation-reduction potential (E°): The ability of an element to attract or lose electrons.

pH: The acidity or basicity level of the solution.

The Pourbaix diagram, also known as the E-pH diagram, is a graphical tool used to predict the stability of different oxidation forms of an element in solution. This chart is built based on two main factors:

Oxidation-reduction potential (E°): The ability of an element to attract or lose electrons.

pH: The acidity or basicity level of the solution.

The Pourbaix diagram can be used to determine the pH and ion concentration conditions required for a particular oxidation form of an element to be stable. This information can then be used to draw a Latimer diagram for that oxidation state.The Pourbaix diagram can also be used to determine the oxidation-reduction reactions that can occur between different oxidation forms of the element. This information can then be used to calculate the oxidation-reduction potentials of those reactions using the Latimer diagram.

2. Conclusion

Using the Latimer diagram will help students easily: (1) Predict the stable oxidation state of the element; (2) Calculate the standard reduction potential of oxidation-reduction pairs that are not close to each other; (3) Predict the products of redox reactions. Thereby, you will develop skills such as "prediction", "calculation", "analysis" when using electrode potential values in different environments to conclude oxidation-reduction reactions. This is a difficult content, demonstrating the combination of electrochemical theory and inorganic chemistry to consider oxidation-reduction reactions that occur. Latimer diagram applications will create excitement for chemistry students when studying inorganic chemistry at universities.

Statement of Competing Interests

The Authors have no competing interests.

References

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[2]   | Atkins, Peter; Overton, Tina; Rourke, Jonathan; Weller, Mark; Armstrong, Fraser; Hagerman, Michael. Inorganic Chemistry (5th ed.). New York: W. H. Freeman. 2010, .
[3]   | Atkins, Peter, Jones, Loretta. Chemical Principles (3rd ed.), W.H. Freeman and Company. 2005, .
[4]   | Brown, Susan A.; Brown, Paul L. "The pH-potential diagram for polonium". The Aqueous Chemistry of Polonium and the Practical Application of its Thermochemistry. Elsevier.
[5]   | Cao Cu Giac, Cao Thi Van Giang and Tran Van Thanh. Designing a Learning Project on Thermodynamics for Chemistry Students According to the CDIO Teaching Mode. World Journal of Chemical Education. 2024; 12(1):6-12.
[6]   | Cotton, F. Albert; ; Murillo, Carlos A.; Bochmann, Manfred. Advanced Inorganic Chemistry (6th ed.), New York: Wiley-Interscience, 1999, 0-471-19957-5.
[7]   | Greenwood, Norman N.; Earnshaw, Alan. Chemistry of the Elements (2nd ed.). . 1997, .
[8]   | Henry Freiser. Enhanced Latimer Potential Diagrams Via Spreadsheets. J. Chem. Educ. 1994, 71, 9, 786.
[9]   | Lide, David R., ed. (87th ed.). Boca Raton, FL: . 2006, .
[10]   | Rieger, P.H. . Electrochemistry. Springer. p. 18. 1993, .
[11]   | V. Rives-Arnau. . Journal of Chemical Education. 1989, 66, 8, 652.
[12]   | Vanýsek, Petr. . In Haynes, William M. (ed.). Handbook of Chemistry and Physics (93rd ed.). CRC Press. pp. 5–80. 2012, .
[13]   | W. F. Giauque. "Wendell M. Latimer, Chemist". Science. 1955, 122 (3166): 406–407.
[14]   | Zumdahl, Steven S., Zumdahl, Susan A. Chemistry (5th ed.), Houghton Mifflin Company. 2000, .