PHD
  1. Inorganic chemistry  1.1. Coordination chemistry  1.1.1. Ligand field theory  1.1.2. Crystal field theory  1.1.3. Molecular Orbital Theory for Coordination Compounds  1.1.4. Stability of Coordination Compounds  1.1.5. Electronic spectra of coordination compounds  1.1.6. Isomerism in Coordination Compounds  1.1.7. Kinetics and mechanism of coordination reactions  1.2. Organometallic Chemistry  1.2.1. Metal Carbonyls  1.2.2. Metal alkyl and aryl  1.2.3. Fischer and Schrock carbonaceans  1.2.4. Oxidative Addition and Reductive Elimination  1.2.5. Metal Hydrides  1.2.6. Catalysis by organometallic compounds  1.2.7. Metallocenes and Sandwich Complexes  1.2.8. CH activation  1.3. Solid state chemistry  1.3.1. Crystal structures and lattices  1.3.2. Band theory and electrical properties  1.3.3. Defects in the crystal  1.3.4. Synthesis of solid state materials  1.3.5. Magnetic and optical properties of solids  1.3.6. Superconductivity  1.3.7. Solid state ionics  1.4. Bio-inorganic chemistry  1.4.1. Metalloproteins and enzymes  1.4.2. Metal ion transport and storage  1.4.3. The role of metals in medicine  1.4.4. Bioinspired catalysis  1.4.5. Metal–DNA interactions  1.4.6. Metal Complexes in Medical Science  1.5. Lanthanides and Actinides  1.5.1. Electronic configuration and oxidation states in lanthanides and actinides  1.5.2. Spectral and Magnetic Properties in Lanthanides and Actinides  1.5.3. Separation and Extraction of Lanthanides and Actinides  1.5.4. Coordination chemistry of f-block elements  1.6. Main Group Chemistry  1.6.1. Chemistry of boron compounds  1.6.2. Chemistry of Silicon and Germanium Compounds  1.6.3. Chemistry of Phosphorus and Sulfur Compounds  1.6.4. Organosilicon chemistry  1.6.5. Noble Gas Chemistry
  2. Organic chemistry  2.1. Reaction mechanism  2.1.1. Nucleophilic substitution reactions  2.1.2. Electrophilic addition and substitution reactions  2.1.3. Elimination reactions  2.1.4. Rearrangement reactions  2.1.5. Radical reactions  2.1.6. Pericyclic Reactions  2.1.7. Photochemical reactions  2.2. Stereoscopic  2.2.1. Chirality and optical activity  2.2.2. Structural analysis  2.2.3. Stereoelectronic effects  2.2.4. Asymmetric synthesis  2.2.5. Dynamic Stereochemistry  2.3. Organometallic Chemistry in Organic Synthesis  2.3.1. Organolithium and organomagnesium reagents  2.3.2. Transition metal catalyzed coupling reactions  2.3.3. Palladium-catalyzed reactions  2.3.4. Olefin Metathesis  2.3.5. Gold and silver catalysis  2.4. Natural products chemistry  2.4.1. Alkaloids and terpenoids  2.4.2. Steroids and Flavonoids  2.4.3. Total synthesis of natural products  2.4.4. Biosynthesis of natural products  2.5. Supramolecular Chemistry  2.5.1. Host-Guest Chemistry  2.5.2. Self-assembly and molecular recognition  2.5.3. Supramolecular Catalysis  2.5.4. Molecular Machines
  3. Physical Chemistry  3.1. Thermodynamics  3.1.1. Laws of Thermodynamics  3.1.2. Chemical Potential and Equilibrium  3.1.3. Statistical thermodynamics  3.1.4. Non-equilibrium thermodynamics  3.2. Quantum Chemistry  3.2.1. Schrödinger equation and its applications  3.2.2. Molecular orbital theory  3.2.3. Density functional theory  3.2.4. Post-Hartree–Fock methods  3.3. Chemical kinetics  3.3.1. Reaction rate theory  3.3.2. Mechanism and rate laws  3.3.3. Catalysis and enzyme kinetics  3.3.4. Reaction dynamics  3.4. Spectroscopy and molecular structure  3.4.1. Infrared Spectroscopy  3.4.2. UV-visible spectroscopy  3.4.3. Nuclear Magnetic Resonance Spectroscopy  3.4.4. Mass Spectrometry  3.4.5. Raman Spectroscopy  3.5. Surface and Colloid Chemistry  3.5.1. Absorption and Catalysis  3.5.2. Surfactants and micelles  3.5.3. Colloidal Stability  3.5.4. Nanomaterials and Interfaces
  4. Analytical chemistry  4.1. Chromatography  4.1.1. Gas Chromatography  4.1.2. High Performance Liquid Chromatography  4.1.3. Thin Layer Chromatography  4.1.4. Ion Chromatography  4.2. Electroanalytical techniques  4.2.1. Voltammetry and Polarography  4.2.2. Conductometry and potentiometry  4.2.3. Colometry  4.3. Spectroscopic Methods  4.3.1. Atomic absorption spectroscopy  4.3.2. Fluorescence Spectroscopy  4.3.3. X-ray diffraction  4.3.4. Electron paramagnetic resonance spectroscopy  4.4. Chemometrics  4.4.1. Data processing and statistical methods  4.4.2. Multidisciplinary analysis  4.4.3. Machine Learning in Analytical Chemistry
  5. Theoretical and Computational Chemistry  5.1. Molecular dynamics simulation  5.2. Quantum chemistry methods  5.3. Computational drug design  5.4. Machine Learning in Chemistry  5.5. Ab initio molecular dynamics
  6. Biophysics and Medicinal Chemistry  6.1. Drug discovery and design  6.2. Enzyme kinetics and inhibition  6.3. Chemical biology approach  6.4. Protein-ligand interactions  6.5. Bioorthogonal chemistry
  7. Materials chemistry  7.1. Polymer chemistry  7.1.1. Polymerization mechanism  7.1.2. Functional Polymers  7.1.3. Biodegradable Polymer  7.1.4. Conducting and semiconducting polymers  7.2. Nano Chemistry  7.2.1. Nanoparticles and nanostructures  7.2.2. Carbon-based nanomaterials  7.2.3. Quantum dots  7.3. Energy and Environmental Chemistry  7.3.1. Battery and Fuel Cell Chemistry  7.3.2. Green chemistry and sustainable materials  7.3.3. Photocatalysis

PHD → Physical Chemistry → Chemical kinetics ↓


Reaction dynamics


Reaction kinetics is a fascinating area of physical chemistry that deals with understanding the mechanisms and rates of chemical reactions at the molecular level. It overlaps with chemical kinetics but takes a deeper look at how the motion of reactants and products changes at the molecular or atomic level. The purpose of this explanation is to provide you with a broad overview of reaction kinetics using simple language, as well as providing visual and text examples throughout.

Introduction to reaction kinetics

In the field of chemical kinetics, scientists study how quickly reactions occur and how different conditions, such as temperature and concentration, affect these rates. However, reaction kinetics goes further to understand the sequence of events that occur when reactants turn into products. This includes studying the paths that atoms and molecules take during a chemical reaction, how energy is transferred, and what transitional states occur.

Theoretical basis of reaction kinetics

Potential energy surfaces

A fundamental concept in reaction kinetics is the potential energy surface (PES). The PES is a multidimensional surface that represents the potential energy of a system of atoms as a function of their atomic positions. It is helpful in visualizing and understanding the paths that a chemical system takes during a reaction.

Potential energy surface

Potential Energy Surface can be thought of as a landscape with hills and valleys, where each point on the landscape represents a particular arrangement of atoms and its corresponding energy. Reactants approach these surfaces, cross activation energy barriers, and become products.

Transition states and activation energy

The key points on the PES are transition states and activation energies. Transition states are the highest energy states on the reaction pathway, representing the point of no return. Activation energy is the energy required to reach this transition state from the reactants.

Transition state theory (TST) is used to describe these states. According to TST:
    - The reactants must overcome an energy barrier (activation energy, Ea).
    - The point with the highest energy on the reaction pathway is the transition state.

As an example, consider a simple one-dimensional reaction:

a + b → [a---b]‡ → AB

Here, [A---B]‡ represents the transition state, and the activation energy is the energy overcome to reach this state from the reactants A and B

Rate constant and reaction mechanism

Reaction kinetics also involves the calculation of rate constants that measure the speed of a reaction. These constants are derived from well-defined reaction mechanisms, which detail the step-by-step pathways of a reaction, including intermediates and transition states.

Reaction path with intermediates

A visualization illustrating this concept could be like a linear graph where the pathway climbs up or down, representing different energy states. Real-world reactions often involve multiple steps and intermediate stages, making pathways complex and multifaceted.

Experimental techniques

Spectroscopy and reaction intermediates

Experimentally, understanding reaction kinetics often involves detecting and analyzing short-lived reaction intermediates. Spectroscopic techniques such as infrared spectroscopy, ultraviolet-visible spectroscopy, and nuclear magnetic resonance (NMR) are powerful tools in this regard.

Laser-based technology

Advanced laser techniques have revolutionized the study of reaction kinetics by providing the ability to investigate processes that occur on very short time scales. Techniques such as femtosecond laser spectroscopy allow scientists to study the very early stages of reactions, often revealing insights about the initial bond-breaking and bond-forming events.

Femtosecond lasers can capture the vibronic states of molecules – these states help us understand the elementary stages of reactions.

Multiscale reaction dynamics

Reactions often occur on a variety of time scales, from femtoseconds to minutes or hours. Therefore, reaction kinetics is intrinsically multiscale, involving integrating molecular dynamics with continuum methods to model these different scales.

Let's take combustion as a practical example. Combustion reactions are essential in energy production and involve fast, complex reactions that must be precisely controlled. The dynamics of combustion involve breaking down the steps of hydrocarbon oxidation, nitrogen oxide formation, and more.

Applications of reaction kinetics

Catalysis

Catalysis, both enzymatic and synthetic, relies heavily on reaction kinetics. Understanding how catalysts lower activation energies and stabilize transition states is crucial for developing more efficient industrial processes.

A typical catalytic reaction:
    E + S → [ES] → [EP] → E + P

where E is the catalyst, S is the substrate, ES is an enzyme-substrate complex, EP is an enzyme-product complex, and P is the product.

Materials science

In materials science, reaction kinetics helps to understand processes such as corrosion, oxidation, and material synthesis. For example, creating new polymers or alloys with specific properties requires a thorough understanding of the reaction pathways and mechanisms involved.

Different material layers

Conclusion

Reaction kinetics provides a detailed view of the complex processes that govern chemical reactions. By combining theory with experimental techniques, this field provides in-depth information about how reactions occur at the atomic and molecular levels. Whether for industrial catalysis, the design of new materials, or the understanding of biological systems, reaction kinetics remains an important and continually evolving area of study in physical chemistry.


PHD → 3.3.4


U
username
0%
completed in PHD

← Prev (3.3.3)
Catalysis and enzyme kinetics
Next (3.4) →
Spectroscopy and molecular structure

Comments 



Reaction dynamics

https://www.chemistryelite.com/phd/3.3.4?ceal=en