Graduate
  1. Physical Chemistry  1.1. Thermodynamics  1.1.1. Laws of Thermodynamics  1.1.2. Enthalpy and heat capacity  1.1.3. Entropy and free energy  1.1.4. Phase Equilibrium  1.1.5. Statistical thermodynamics  1.1.6. Thermodynamic cycle  1.1.7. Fugacity and activity  1.2. Quantum Chemistry  1.2.1. Principles of quantum mechanics  1.2.2. Schrödinger Equation  1.2.3. Particle in a box  1.2.4. Operators and eigenvalues  1.2.5. Atomic orbitals  1.2.6. Molecular orbital theory  1.2.7. Perturbation theory  1.2.8. Valence bond theory  1.2.9. Hybridization and chemical bonding  1.3. Chemical kinetics  1.3.1. Rate laws and reaction mechanisms  1.3.2. Collision theory  1.3.3. Transition state theory  1.3.4. Enzyme Kinetics  1.3.5. Chain Reactions and Polymerization  1.3.6. Photochemical reactions  1.4. Statistical mechanics  1.4.1. Partitioning functions  1.4.2. Molecular distribution functions  1.4.3. Boltzmann Distribution  1.4.4. Bose–Einstein and Fermi–Dirac statistics  1.5. Spectroscopy  1.5.1. Rotational Spectroscopy  1.5.2. Vibrational Spectroscopy  1.5.3. Electronic Spectroscopy  1.5.4. Nuclear magnetic resonance spectroscopy  1.5.5. Mass Spectrometry  1.5.6. Raman Spectroscopy  1.5.7. Electron paramagnetic resonance spectroscopy  1.6. Surface and colloidal chemistry  1.6.1. Absorption isotherm  1.6.2. Surface tension and wetting  1.6.3. Colloidal Stability  1.6.4. Catalysis  1.6.5. Emulsions and micelles  1.7. Electrochemistry  1.7.1. Nernst equation  1.7.2. Electrochemical cells  1.7.3. Conductivity and mobility  1.7.4. War  1.7.5. Fuel cells  1.7.6. Electrolysis
  2. Organic chemistry  2.1. Reaction mechanism  2.1.1. Nucleophilic substitution reactions  2.1.2. Electrophilic addition reactions  2.1.3. Elimination reactions  2.1.4. Rearrangement reactions  2.1.5. Radical reactions  2.1.6. Pericyclic reactions  2.2. Spectroscopy and structural determination  2.2.1. UV-Vis Spectroscopy  2.2.2. IR Spectroscopy  2.2.3. NMR Spectroscopy  2.2.4. Mass Spectrometry  2.2.5. X-ray crystallography  2.3. Stereoscopic  2.3.1. Chirality and optical activity  2.3.2. Structural analysis  2.3.3. Geometrical isomerism  2.3.4. Dynamic Stereochemistry  2.4. Organometallic Chemistry  2.4.1. Organolithium and organomagnesium reagents  2.4.2. Palladium-catalyzed cross-coupling reactions  2.4.3. Transition Metal Complexes  2.4.4. Metal–carbon bond  2.5. Polymer chemistry  2.5.1. Polymerization mechanism  2.5.2. Polymer Characteristics  2.5.3. Biodegradable Polymer  2.5.4. Conducting polymer  2.5.5. Supramolecular polymers  2.6. Medicinal chemistry  2.6.1. Drug design and development  2.6.2. Pharmacokinetics and pharmacodynamics  2.6.3. Structure-activity relationships  2.6.4. Molecular docking and drug screening
  3. Inorganic chemistry  3.1. Coordination chemistry  3.1.1. Crystal field theory  3.1.2. Ligand field theory  3.1.3. Spectrochemical Series  3.1.4. Chelation and stability  3.2. Organometallic Chemistry  3.2.1. Metal Carbonyls  3.2.2. Catalysis by organometallic complexes  3.2.3. Metallocenes  3.3. Bio-inorganic chemistry  3.3.1. Metalloproteins and enzymes  3.3.2. The role of metals in biological systems  3.3.3. Metal ion transport and storage  3.4. Solid state chemistry  3.4.1. Crystal Structures  3.4.2. Band theory of solids  3.4.3. Superconductors  3.4.4. Defects in the crystal  3.5. Lanthanides and Actinides  3.5.1. Electronic configuration in lanthanides and actinides  3.5.2. Coordination chemistry of the lanthanides  3.5.3. Magnetic Properties of Lanthanides
  4. Analytical chemistry  4.1. Chromatography  4.1.1. Gas Chromatography  4.1.2. High Performance Liquid Chromatography  4.1.3. Thin Layer Chromatography  4.2. Spectroscopic Techniques  4.2.1. Atomic absorption spectroscopy  4.2.2. X-ray diffraction  4.2.3. Inductively coupled plasma spectroscopy  4.3. Electroanalytical methods  4.3.1. Potentiometry  4.3.2. Voltammetry  4.3.3. Colometry  4.4. Mass Spectrometry  4.4.1. Ionization Technique  4.4.2. Fragmentation Pattern  4.5. Chemometrics  4.5.1. Multidisciplinary analysis  4.5.2. Machine Learning in Chemistry
  5. Theoretical and Computational Chemistry  5.1. Molecular dynamics simulation  5.1.1. Force fields and energy minimization  5.1.2. Monte Carlo simulation in molecular dynamics simulations  5.2. Quantum chemical methods  5.2.1. Hartree–Fock theory  5.2.2. Density functional theory  5.2.3. Semi-empirical methods  5.3. Computational drug design  5.3.1. Molecular Docking  5.3.2. QSAR Modeling  5.3.3. Virtual Screening
  6. Biochemistry  6.1. Enzyme Kinetics  6.1.1. Michaelis-Menten kinetics  6.1.2. Inhibition mechanism  6.2. Metabolism and Bioenergetics  6.2.1. Glycolysis  6.2.2. Citric acid cycle  6.2.3. Electron transport chain  6.3. molecular Biology  6.3.1. DNA replication and repair  6.3.2. Protein synthesis  6.3.3. Gene Regulation  6.4. Structural Biochemistry  6.4.1. Protein Folding  6.4.2. Membrane Biophysics
  7. Environmental Chemistry  7.1. Atmospheric Chemistry  7.1.1. Greenhouse gases  7.1.2. Ozone depletion  7.1.3. Air pollutants and smoke  7.2. Water Chemistry  7.2.1. pH and water hardness  7.2.2. Wastewater treatment  7.2.3. Aquatic Chemistry  7.3. Soil Chemistry  7.3.1. Heavy metal contamination  7.3.2. Soil pH and Buffering  7.3.3. Nutrient cycling  7.4. Toxicology and Chemical Safety  7.4.1. Toxicokinetics  7.4.2. Risk Assessment in Toxicology and Chemical Safety in Environmental Chemistry  7.4.3. Effects of pollutants on the environment

Graduate → Physical Chemistry ↓


Chemical kinetics


Chemical kinetics is a branch of physical chemistry that studies the rates of chemical reactions and the steps in which they occur. It is an important field of study because understanding the speed and mechanisms of chemical reactions helps chemists control them, optimize industrial processes, and understand natural phenomena.

The basics of reaction rates

In chemical kinetics, the reaction rate is a measure of how quickly the concentration of reactants decreases or how quickly the concentration of products increases. The rate of a chemical reaction can be expressed as:

Rate = -d[A]/dt = d[B]/dt

Here, [A] and [B] are the concentrations of reactant A and product B, respectively. The negative sign indicates that the concentration of A is decreasing as the reaction proceeds.

Factors affecting the reaction rate

Concentration

Changing the concentration of the reactants can affect the rate of the reaction. In general, increasing the concentration of the reactants increases the rate of the reaction because more particles can collide.

Temperature

Increasing the temperature generally increases the rate of the reaction. This occurs because higher temperatures increase the kinetic energy of the molecules, leading to more effective collisions. The Arrhenius equation can describe this effect:

k = Ae^(-Ea/RT)

where k is the rate constant, A is the pre-exponential factor, Ea is the activation energy, R is the gas constant, and T is the temperature in Kelvin.

Surface area

The larger surface area of a solid reactant increases the rate of the reaction because more particles are exposed to react.

Catalyst

Catalysts increase the rate of a reaction without being consumed in the process. They work by lowering the activation energy needed for the reaction to proceed.

Reaction mechanism

Reaction mechanisms describe the step-by-step sequence of elementary reactions by which an overall chemical transformation occurs. Mechanisms are essential for understanding how reactions occur at the molecular level.

Example of a reaction mechanism

Consider the reaction between NO2 and CO to form NO and CO.

NO2 + CO → NO + CO2

This may happen through the following elementary steps:

Step 1: NO2 + NO2 → NO + NO3
Step 2: NO3 + CO → NO2 + CO2

These elementary steps must be included in the overall balanced equation. The rate of the reaction is often determined by the slowest step, known as the rate-determining step.

Order of reaction

The order of a reaction refers to the power to which the concentration term in the rate equation is raised. Reaction orders are determined experimentally and can be described as follows:

Rate = k[A]^m[B]^n

where m and n represent the relative order of reactants A and B, respectively.

Zero-order reactions

For zero-order reactions, the rate is independent of the reactant concentration.

Rate = k

An example of this is the decomposition of ammonia on a platinum surface at high pressure.

First-order reactions

The rate of a first-order reaction is proportional to the concentration of the reactant.

Rate = k[A]

Example: radioactive decay.

Second-order reactions

For second-order reactions, the velocity is either proportional to the square of the concentration of a single reactant, or proportional to the product of the concentrations of two different reactants.

Rate = k[A]^2 or Rate = k[A][B]

Role of collision theory

Collision theory helps explain how chemical reactions occur and why they occur at different rates. According to this theory:

  • For a reaction to take place, the molecules must collide with each other.
  • Not all collisions result in a reaction; only those with enough energy and the right orientation will produce a reaction.

Visualization: Collision theory

Molecule A Molecule B Successful collision

Conclusion

Understanding chemical kinetics is important to both theoretical chemistry and industrial processes. By carefully manipulating variables such as concentrations, temperature, and catalysts, chemists can control reaction rates and design more efficient chemical processes. Theoretical frameworks such as collision theory and transition state theory provide deep insights into the molecular dynamics of reactions.

In conclusion, chemical kinetics is a fundamental field of study that combines theory and practical applications. It opens the door to new technologies and processes that can advance advances in chemical manufacturing, pharmaceuticals, and environmental science.


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Chemical kinetics

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