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

To unsubscribe from our mailing list, please click on the following link: unsubscribe

I am looking forward to hearing from you.

Kind regards,

David Rain
Email:join@sciepub.com
Science and Education Publishing (http://www.sciepub.com)

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

To unsubscribe from our mailing list, please click on the following link: unsubscribe

I am looking forward to hearing from you.

Kind regards,

David Rain
Email:join@sciepub.com
Science and Education Publishing (http://www.sciepub.com)

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

To unsubscribe from our mailing list, please click on the following link: unsubscribe

I am looking forward to hearing from you.

Kind regards,

David Rain
Email:join@sciepub.com
Science and Education Publishing (http://www.sciepub.com)

Are the Stoichiometric Coefficients in a Chemical Reaction Indication of the Kinetic Orders of the Reactants? An Inspiration to Chemistry Graduate Students

Y. Sharanya, N. Keerthana, V. Rajeswari, Sanjeev Rachuru, D. A. Padmavathi, V. Jagannadham*, G. Ramya Sree

Department of Chemistry, Osmania University, Hyderabad-500007, India

Abstract: It is a general tendency of the students and some of the teachers of chemistry that they conceive the stoichiometric coefficients of a balanced equation of a chemical reaction are the individual kinetic orders of those reactants involved in the rate equation of that reaction. But this is not true. The stoichiometric coefficients have nothing to do with individual kinetic orders of the reactants involved in the reaction or in the rate equation. A detailed explanation with a suitable example for this misconception is provided in the present article.

Keywords: Stoichiometric coefficients, Rate equation, Rate law, Order of a reaction

Received October 27, 2025; Revised November 29, 2025; Accepted December 05, 2025 #Post-Graduate students

Citation: Y. Sharanya, N. Keerthana, V. Rajeswari, Sanjeev Rachuru, D. A. Padmavathi, V. Jagannadham, G. Ramya Sree, Are the Stoichiometric Coefficients in a Chemical Reaction Indication of the Kinetic Orders of the Reactants? An Inspiration to Chemistry Graduate Students. World Journal of Chemical Education, 13 (4). 103-106. January 2025. doi:10.12691/wjce-13-4-3

1. Introduction

A chemical equation represents a chemical reaction. It shows the reactants that start a reaction, and products formed by the reaction. A balanced equation obeys the law of conservation of mass. Similarly, a rate equation represents in chemistry, also known as the rate law or differential rate equation is an empirical differential mathematical expression for the reaction rate of a given reaction in terms of concentrations of chemical species and constant parameters normally rate coefficients and individual kinetic orders of the reaction [1]. For many reactions, the initial rate is given by an equation comprising of powers of the reactants such as

(Rate)o = k [A]x [B]yv0=k[A]x[B]y

where ⁠[A][A] and [B] ⁠[B] are the molar concentrations of the species A ⁠and ⁠B, usually in moles per liter and k is the specific reaction rate or rate constant. And ‘x’ and ‘y’ are the individual kinetic orders of the reactants, and they are experimentally determinable. The kinetic orders x and y may be integers, or fractional or zero. The total kinetic order of the reaction is therefore (x + y).

2. Methods

Chemical structures are drawn using “ChemDraw” software. The individual orders of persulfate and iodide ions are determined from initial rate measurements. All the plots are constructed using KaleidaGraph software version 4.1 supplied by Synergy Software, Reading, PA USA.

Reactions are followed by mixing solutions of required concentrations of KI and K₂S₂O₈ and titrating 5 mL of the reaction mixture at regular intervals of time with standard thiosulfate solution. Figure 1 is the exponential rise plot of volume of hypo versus time keeping [KI] constant at 0.04 M and varying [K₂S₂O₈] from 0.0125 M to 0.020 M at a total ionic strength of 0.13 M maintained by using required amounts of K₂SO₄ solution and at 25 C. Initial rates are calculated using the exponential equation y = m1 + m2*(1 − e−m3*x), where m1 and m2 are some arbitrary constants and m3 is the coefficient of ‘x’ that is time axis which gives the rate of the reaction. Data is presented in Table 1.

Figure 2 is the plot of log (initial rate) versus log [K₂S₂O₈], slope of which gives the order with respect to [K₂S₂O₈]. And the order with respect to [K₂S₂O₈] is coming out to be 1.01. The data is given in Table 1.

Similarly, figure 3 is the exponential rise plot of volume of hypo versus time keeping [K₂S₂O₈] constant at 0.025 M and varying [KI] from 0.03 M to 0.045 M at a total ionic strength of 0.106 M and at 25C.

Figure 4 is the plot of log (initial rate) versus log [KI], slope of which gives the order with respect to [KI]. And the order with respect to [KI] is coming out to be 1.38. Data is given in Table 2.

Figure 1. Plot of volume of hypo vs time with changing [K₂S₂O₈]

Figure 2. Plot of log (initial rate) vs log[K₂S₂O₈]

Figure 3. Plot of volume of hypo vs time with changing [KI]

Table 1. Initial rate data with varying [K₂S₂O₈]

Table 2. Initial rate data with varying [KI]

Figure 4. Plot of log (initial rate) vs log [KI]

We have taken the order in [KI] as 1.00 though the graph gave 1.38 which we have considered as some experimental limitations. Therefore, from orders in [K₂S₂O₈] and [KI] the rate equation would be:

(Rate)o = k [K₂S₂O₈]¹ [KI]¹v0=k[A]x[B]y

3. Discussion

As mentioned in the abstract, to explain the problem in detail, let us take the balanced reaction between persulphate ion and iodide ion (equation 1).

[picture] | (1)

As argued in the abstract if the stoichiometric coefficients are taken as individual kinetic orders of the reactants, and if the reaction step in equation 1 is the rate determining step, the rate equation for this reaction would be:

[picture] | (2)

Which indicates that the individual kinetic orders of persulphate ion is 1 and that of iodide ion is 2. Thus, the total order of the reaction is 1 + 2 = 3. This means that the rate determining step should involve one mole of persulphate ion and two moles of iodide ion, gives the rate determining step as:

[picture] | (3)

And this lone reaction step should represent the total mechanism of the reaction. In fact, this was reported in iodine clock reaction where the order with respect to persulfate is one and that of iodide is two [2]. But literature survey reveals that the total kinetic order of this reaction is not 3 and the individual kinetic order of iodide ion is not 2. The experimentally observed individual kinetic orders of persulphate and iodide ions are 1 each leading to the total kinetic order of the reaction is 2 [3,4]. Therefore, the mechanism of the reaction is not the sole mechanism as mentioned in equation 3. And the rate equation would then be as mentioned in equation 4:

[picture] | (4)

The total kinetic order would then be 1 + 1 = 2. The kinetic orders of the reactants participating in the rate determining step as shown in equation 5 below are not equal or need not be equal to the stoichiometric coefficients of equation 1. Therefore, the mechanism of this reaction should involve one mole of each persulphate and iodide ions in the rate determining step to satisfy the rate equation 4 will be:

Taking the rate determining step 5, the rate equation would be as mentioned in equation 4. If one adds all the four steps 5, 6, 7 and 8 one will get the stoichiometric equation 1. And at the same time the mechanism satisfies the total kinetic order of the reaction is 1 + 1 = 2 and its stoichiometry. The equations 5, 6, 7 and 8 represent the final mechanism of the reaction (Scheme 1).

Persulphate is structurally similar to hydrogen peroxide.

In hydrogen peroxide the two hydrogens are replaced by two groups. Therefore, it is believed that redox process that occurs persulphate oxidations resembles that of hydrogen peroxide [5]. The lucid mechanism shows simultaneous homolytic cleavage of peroxide bond forming sulphate radical ion () and sulphate radical ion–iodide ion adduct [5] (equation 5). The occurrence of has been well-documented by time resolved UV-VIS spectroscopy identifying its transient absorbance at 450 nm with a molar extinction coefficient of 460 M⁻¹cm⁻¹ [6]. The sulphate radical ion–iodide ion adduct then by intramolecular electron transfer from sulphate radical ion moiety to iodide ion gives sulphate ion and iodine atom as shown in equation 6 (scheme 1). The sulphate radical ion thus formed in equation 5 reacts with another mole of iodide ion as shown in equation 7 to give sulphate ion and iodine atom. The two iodine atoms thus formed in equations 6 and 7 finally give molecular iodine (step 8). Hence the mechanism represents that it is the oxidation of iodide ion by sulphate radical ion within the adduct (step 6). The first step of this process of scheme 1 is termed as energy transfer through thermolysis [5]. The reaction between H₂O₂ and iodide ion under neutral conditions is in fact shown to follow the rate equation 9 [7] similar to the present work (equation 4):

Rate = k [I−]¹ [H₂O₂]¹(9)

For the benefit of the students, one can read the paper published elsewhere by one of the authors (VJ) [8] on the detailed kinetics of hydrolysis of methyl acetate and for conceptual comprehension of the terms negative order and fractional order in the field of chemical kinetics [9].

Conflict of Interest:

The authors don’t have any conflict of interest.

Funding

We did not receive any funding from any source.

References

[1]   | Gold, Victor, ed. (2019). The IUPAC Compendium of Chemical Terminology: The Gold Book (4th ed.). Research Triangle Park, NC: International Union of Pure and Applied Chemistry (IUPAC).
[2]   | Chrome-extension:// efaidnbmnnnibpcajpcglclefindmkaj/ http:// www.kentchemistry.com/. Labs/ iodineclock.pdf.
[3]   | A. Indelli and J. E. Prue, J. Chem. Soc., 1959, 107-111.
[4]   | P. C. Moews, Jr. and R. H. Petrucci, Journal of Chemical Education, Volume 41, 1964, page 548.
[5]   | Jaesang Lee, Urs von Gunten, and Jae-Hong Kim, Environ. Sci. Technol., 2020.
[6]   | P. Neta, V. Madhavan, H. Zemel, and R. W. Fessenden, J. Amer. Chem. Soc. 1977, 99, 163-164.
[7]   | George T. F. Wong, Ling-Su Zhang, Marine Chemistry, 111 (2008) 22–29.
[8]   | V. Jagannadham, Khimiya/Chemistry (The Bulgarian Journal of Chemical Education), (2010) vol. 19, page 114.
[9]   | R. Sanjeev, V. Jagannadham, Adam A Skelton, R. Veda Vrath, World Journal of Chemical Education 2.1 (2014): 4-7.