1) Latimer, Frost, and Pourbaix diagrams are used to predict and summarize redox reactions in aqueous solutions. Latimer diagrams list standard potentials for step-wise reductions while Frost diagrams plot free energy vs oxidation state. Pourbaix diagrams show predominant species as a function of both potential and pH.
2) Latimer and Frost diagrams are restricted to pH 0 or 14 while Pourbaix diagrams cover the full pH range from 0-14. Pourbaix diagrams indicate the most stable species under given conditions and can identify strong oxidizers, reducers, and species prone to disproportionation.
3) These diagram types are useful tools for predicting thermodynamic favorability and identifying stable vs unstable oxidation states of
ELECTRICAL DOUBLE LAYER-TYPES-DYNAMICS OF ELECTRON TRANSFER-MARCUS THEORY-TUNNELING - BUTLER VOLMER EQUATIONS-TAFEL EQUATIONS-POLARIZATION AND OVERVOLTAGE-CORROSION AND PASSIVITY-POURBAIX AND EVAN DIAGRAM-POWER STORAGE-FUEL CELLS
These are chemical shift reagents and solvent induced shifts have their application in resolving the NMR Spectra of complex structures by inducing shift with respect to reference compound. Thus useful in interpretation of structures of complex organic compounds.
Introductory PPT on Metal Carbonyls having its' classification,structure and applications.This is a basic level PPT specially prepared for UG/PG Chemistry students.
Zeigler Natta catalyst is an important class of chemical compounds remarfot their ability to effect the polymerization of olefin to polymers of high molecular weights and streoregular structures.
It was developed by German SCientist Karl Zeigler and Itanlian scientist Giulio Natta and they received the 1963 Nobel prize in chemistry.
It's a combination of organimetallics which consists of a complex Triethyl aluminum an transition metal halide(Titanium tetrachloride ) which analysis polymerization.
Other transition metal such as Vanadium,Zirconium,Chromium, have also proven effective.
This Presentation describes about the evidence of metal ligand bonding in a molecule. In this presentation various evidences are explained. Learn and grow.
ELECTRICAL DOUBLE LAYER-TYPES-DYNAMICS OF ELECTRON TRANSFER-MARCUS THEORY-TUNNELING - BUTLER VOLMER EQUATIONS-TAFEL EQUATIONS-POLARIZATION AND OVERVOLTAGE-CORROSION AND PASSIVITY-POURBAIX AND EVAN DIAGRAM-POWER STORAGE-FUEL CELLS
These are chemical shift reagents and solvent induced shifts have their application in resolving the NMR Spectra of complex structures by inducing shift with respect to reference compound. Thus useful in interpretation of structures of complex organic compounds.
Introductory PPT on Metal Carbonyls having its' classification,structure and applications.This is a basic level PPT specially prepared for UG/PG Chemistry students.
Zeigler Natta catalyst is an important class of chemical compounds remarfot their ability to effect the polymerization of olefin to polymers of high molecular weights and streoregular structures.
It was developed by German SCientist Karl Zeigler and Itanlian scientist Giulio Natta and they received the 1963 Nobel prize in chemistry.
It's a combination of organimetallics which consists of a complex Triethyl aluminum an transition metal halide(Titanium tetrachloride ) which analysis polymerization.
Other transition metal such as Vanadium,Zirconium,Chromium, have also proven effective.
This Presentation describes about the evidence of metal ligand bonding in a molecule. In this presentation various evidences are explained. Learn and grow.
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Oxidation reactions in chemical engineering. Oxidation state. Oxidation state changes. Identify the element oxidized . Oxidation and reduction half-reactions.
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Balancing Oxidation Reduction Equations. The sulfite ion concentration present in wastewater from a papermaking plant.
Oxidizing and reducing agents
Complex-formation reactions are widely used in analytical chemistry. One of the first uses of these reagents was for titrating cations. In addition, many complexes are colored or absorb ultraviolet radiation; the formation of these complexes is often the basis for spectrophotometric determinations. Some complexes are sparingly soluble and can be used in gravimetric analysis. Complexes are also widely used for extracting cations from one solvent to another and for dissolving insoluble precipitates. The most useful complex forming reagents are organic compounds that contain several electron donor groups that form multiple covalent bonds with metal ions.
FORMING COMPLEXES
Most metal ions react with electron-pair donors to form coordination compounds or complexes. The donor species, or ligand is an ion or a molecule that forms a covalent bond with a cation or a neutral metal atom by donating a pair of electrons that are then shared by the two.
The number of covalent bonds that a cation tends to form with electron donors is its coordination number. Typical values for coordination numbers are two, four, and six. The species formed as a result of coordination can be electrically positive, neutral, or negative.
A ligand that has a single donor group, such as ammonia, is called unidentate(single-toothed), whereas one such as glycine, which has two groups available for covalent bonding, is called bidenate. Tridentate, tetradentate, pentadentate, and hexadentate chelating agents are also known.
Another important type of complex, a macrocycle, is formed between a metal ion and a cyclic organic compound. The selectivity of a ligand for one metal ion over another relates to the stability of the complexes formed. The higher the formation constant of a metal-ligand complex, the better the selectivity of the ligand for the metal relative to similar complexes formed with other metals.
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Artificial Intelligence (AI) technologies such as Generative AI, Image Generators and Large Language Models have had a dramatic impact on teaching, learning and assessment over the past 18 months. The most immediate threat AI posed was to Academic Integrity with Higher Education Institutes (HEIs) focusing their efforts on combating the use of GenAI in assessment. Guidelines were developed for staff and students, policies put in place too. Innovative educators have forged paths in the use of Generative AI for teaching, learning and assessments leading to pockets of transformation springing up across HEIs, often with little or no top-down guidance, support or direction.
This Gasta posits a strategic approach to integrating AI into HEIs to prepare staff, students and the curriculum for an evolving world and workplace. We will highlight the advantages of working with these technologies beyond the realm of teaching, learning and assessment by considering prompt engineering skills, industry impact, curriculum changes, and the need for staff upskilling. In contrast, not engaging strategically with Generative AI poses risks, including falling behind peers, missed opportunities and failing to ensure our graduates remain employable. The rapid evolution of AI technologies necessitates a proactive and strategic approach if we are to remain relevant.
1. Redox Reactions in Aqueous
Media
[Paper 2- Co-ordination Chemistry]
- Jaiswal Priyanka Balister
M.Sc- II [Inorganic]
Semester III
Mithibai College
2. The Diagrammatic Presentation of
Potential Data
There are three main methods of predicting redox reactions in aqueous solutions,
summarising the thermodynamic stabilities of oxidation states of elements in aqueous
solutions.
1. LATIMER DIAGRAM
2. VOLT EQUIVALENT [Also known as Frost (Free energy oxidation state) diagram
These two are usually restricted to extremes of pH=0 or pH=14 solutions.
3. Pourbaix diagram
It expresses the variation in stabilities of oxidation states as a function of pH between pH
values 0 to 14.
3. 1. Latimer Diagrams
It is a list of various oxidation states of an element arranged in descending
order from left to right.
The numerical value of standard potential is written over a horizontal line
connecting species of element in different oxidation states.
Most oxidised form is on the left.
Species to the right are in successively lower oxidation states.
Available for all the elements exhibiting more than one oxidation state.
4. Latimer diagram for Manganese [acidic
medium]
The Latimer diagram for Mn illustrates its standard reduction potentials (in 1M
HCl) in oxidation states from +7 to 0.
It compresses into shorthand notation all the standard potentials for redox
reactions of element Mn.
Values for multi-electron reactions can be also calculated by first adding ∆Gº
(nFEº) values and then dividing by the total no of electrons.
5. Calculation of values for multi-electron reactions by first adding
ΔG°(=-nFE°) values and then dividing by the total number of electrons
for the 5-electron reduction of MnO4
- to Mn2+, we write
for the three-electron reduction of MnO4
-(aq) to MnO2(s),
6. Thermodynamically stable & unstable
oxidation states
An unstable species on a Latimer diagram will have a lower standard
potential to the left than to the right.
2 MnO4
-3 → MnO2 + MnO4
2- ; MnO4
-3 is unstable.
Eº = +4.27 − 0.274 = +3.997V ; (spontaneous disproportionation)
Which Mn species are unstable with respect to disproportionation?
MnO4
-3 ; 5+ → 6+, 4+
Mn3+ ; 3+→4+, 2+
So stable species are MnO4
-, MnO2, MnO4
2-, Mn2+, Mn0
Thermodynamically unstable ions can be quite stable kinetically.
7. Disproportionation
In most redox reactions atoms of one element are oxidized and atoms of a different
element are reduced.
In some redox reactions a single substance can be both oxidized and reduced.
These are known as disproportionation reactions.
Example : Decomposition reaction of H2O2
2 H2O2(aq) → 2 H2O(l) + O2(g)
The decomposition reaction of hydrogen peroxide produces oxygen and water.
Oxygen is present in all parts of the chemical equation and as a result it is both
oxidized and reduced.
8. 2. Frost Diagrams
In a Frost diagram, we plot ΔG°⁄F (= nE°) vs.
oxidation number.
The zero oxidation state is assigned a nE° value of
zero.
Contains the same information as in a Latimer
diagram, but graphically shows stability and oxidizing
power.
Stable and unstable oxidation states can be easily
identified in the plot.
The standard potential for any electrochemical
reaction is given by the slope of the line connecting
the two species on a Frost diagram.
9. What You Can Learn From a Frost
Diagram:
Thermodynamic stability is found at the bottom of the
diagram. Thus, the lower a species is positioned on the
diagram, the more thermodynamically stable it is (from a
oxidation-reduction perspective)
Mn (II) is the most stable species.
Any species located on the upper left side of the diagram
will be a strong oxidizing agent.
MnO4
- is a strong oxidizer.
Any species located on the upper left side of the diagram
will be a strong oxidizing agent.
MnO4
- is a strong oxidizer.
The information obtained from a Frost diagram is for
species under standard conditions (pH=0 for acidic
solution and pH=14 for basic solution).
10. 3. Pourbaix Diagrams
Plots of E versus pH for various couples in oxidation of an element.
The Pourbaix diagram is a type of predominance diagram -- it shows the
predominate form in an element will exist under a given set of environmental
conditions.
These diagrams give a visual representation of the oxidizing and reducing abilities
of the major stable compounds of an element and are used frequently in
geochemical, environmental and corrosion applications.
Like Frost diagrams, Pourbaix diagrams display thermodynamically preferred
species.
11. How to Read a Pourbaix Diagram
Vertical lines separate species that are in acid-base
equilibrium.
Non vertical lines separate species related by redox
equilibria.
Horizontal lines separate species in redox equilibria not
involving hydrogen or hydroxide ions.
Diagonal boundaries separate species in redox equilibria
in which hydroxide or hydrogen ions are involved.
Dashed lines enclose the practical region of stability of
the water solvent to oxidation or reduction.
12. What You Can Learn From a Pourbaix
Diagram
Any point on the diagram will give the thermodynamically most stable
form of that element at a given potential and pH condition.
Strong oxidizing agents and oxidizing conditions are found only at the top
of Pourbaix diagrams.
Strong oxidizing agents have lower boundaries that are also high on the
diagram.
Permanganate is an oxidizing agent over all pH ranges. It is very strongly
oxidizing at low pH.
A species that ranges from the top to the bottom of the diagram at a
given pH will have no oxidizing or reducing properties at that pH.
13. What You Can Learn From a Pourbaix
Diagram
Reducing agents and reducing conditions are found at the bottom of a diagram
and not elsewhere.
Strong reducing agents have low upper boundaries on the diagram.
Manganese metal is a reducing agent over all pH ranges and is strongest in basic
conditions.
When the predominance area for a given oxidation state disappears completely
above or below a given pH and the element is in an intermediate oxidation state,
the element will undergo disproportionation
MnO4
2- tends to disproportionate.
14. Bibliography
1. Rayner- Canham, G. Descriptive Inorganic Chemistry; Freeman:New York,1996;
Chapter 9
2. Douglas, B; McDaniel, D.; Alexander, J. Concepts and Models of Inorganic
Chemistry, 3rd ed.; Wiley & Sons: New York, 1994; Chapter 8.
3. J. Kotz, P. Treichel, J. Townsend, D. Treiche, Chemistry & Chemical Reactivity, 9th ed.
; Cengage Learning.
4. J.E. Huheey, E.A. Keiter, R.L. Keiter, O.K. Medhi, Inorganic Chemistry: Principles of
Structure and Reactivity, 4th ed. ; Pearson Education.