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 → Thermodynamics ↓


Thermodynamic cycle


The thermodynamic cycle is a fundamental concept in thermodynamics, especially in the study of heat engines, refrigerators, and various energy systems. A thermodynamic cycle consists of a series of processes that return a system to its initial state. During these processes, energy is transferred within the system, often in the form of work and heat. The concept of thermodynamic cycles is important in understanding how heat engines convert heat into work, how refrigerators move heat away from a cold region, and how various energy transformations occur.

Basic concepts

In thermodynamics, a cycle involves a sequence of thermodynamic processes that begin and end in the same thermodynamic state, which usually means that the system returns to its original physical, chemical, or thermal state. Here is a simple representation:

        Case 1 → Process A → Case 2 → Process B → Case 3 → Process C → Case 4 → Process D → Case 1

A complete cycle generates an energy exchange with the environment, usually work done by the system or heat absorbed by the system. Studying these cycles helps us understand how energy is transferred and transformed.

Major thermodynamic cycles

There are several major thermodynamic cycles that form the basis of many practical and theoretical systems:

1. Carnot cycle

The Carnot cycle is a theoretical model that describes the maximum possible efficiency that can be achieved by a heat engine when converting heat into work or vice versa. It consists of two isothermal processes and two adiabatic processes and is used as an ideal reference for real-world heat engines. The cycle consists of:

  • Isothermal expansion
  • Adiabatic expansion
  • Isothermal compression
  • Adiabatic compression
Isothermal expansion Isothermal compression Adiabatic expansion Adiabatic compression

The efficiency of the Carnot cycle is determined by the temperatures of the hot and cold reservoirs: Efficiency = 1 - (Tcold /Thot ), where temperatures are in Kelvin.

2. Otto cycle

The Otto cycle is the ideal cycle for spark-ignition internal combustion engines such as those found in cars. The cycle is named after Nicolaus Otto, the German engineer who invented the gasoline engine. The cycle consists of four processes:

  • Isentropic compression
  • Constant volume heat addition
  • Isentropic expansion
  • Constant volume heat rejection
Pressure Expansion

The efficiency for the Otto cycle is given as: Efficiency = 1 - (1/compression Ratioγ-1 ), where γ is the ratio of specific heats.

3. Diesel cycle

The Diesel cycle describes the workings of a diesel engine, which uses compression ignition rather than the spark ignition found in the Otto cycle. This cycle consists of:

  • Isentropic compression
  • Constant pressure heat promotion
  • Isentropic expansion
  • Constant volume heat rejection
Pressure Expansion

The efficiency for the Diesel cycle is: Efficiency = 1 - 1/rγ-1 * [(Pcutoff )γ - 1], where r is the compression ratio and Pcutoff is the cutoff ratio.

4. Rankine cycle

The Rankine cycle is the ideal cycle for steam turbine power plants commonly found in electricity generation. It consists of four major processes:

  • Isentropic expansion
  • Isothermal expansion
  • Isothermal compression
  • Isentropic compression
Expansion Pressure

This cycle helps us understand how thermal energy produced by combustion of fuel can be converted into mechanical energy.

Applications of thermodynamic cycles

Thermodynamic cycles have wide applications in various engineering and scientific fields:

Power generation

Power plants such as coal, nuclear, or natural gas use cycles such as the Rankine cycle to convert thermal energy produced by combustion or nuclear reactions into mechanical energy, which is ultimately converted into electrical energy.

Automotive engines

Automobile engines use the Otto cycle (for gasoline engines) and the Diesel cycle (for diesel engines) to efficiently convert fuel into work.

Refrigeration and heat pumps

These cycles are used in refrigerators and air conditioning systems to transfer heat from a cold area to a warm area, maintaining the desired temperature in the interior space.

Conclusion

Understanding thermodynamic cycles is fundamental in the design and analysis of systems that involve energy transformation and work production. These cycles provide important insights into optimizing the energy efficiency of engines, vehicles, power plants, and many other technological applications. By analyzing the processes involved in each cycle, scientists and engineers can enhance performance and develop innovative solutions for energy transformation and use.


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Thermodynamic cycle

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