Kinetic Molecular Theory
Kinetic Molecular Theory - Related Videos
03:07
Kinetic Molecular Theory: Molecular Velocities, Temperature, and Kinetic Energy
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2020
The kinetic molecular theory qualitatively explains the behaviors described by the various gas laws. The postulates of this theory may be applied in a more quantitative fashion to derive these individual laws. Collectively, the molecules in a sample of gas have average kinetic energy and average speed; but individually, they move at different speeds. Molecules frequently undergo elastic collisions in which the momentum is conserved. Since the colliding molecules are deflected off at different...
02:43
Basic Postulates of Kinetic Molecular Theory: Particle Size, Energy, and Collision
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2020
The ideal-gas equation, which is empirical, describes the behavior of gases by establishing relationships between their macroscopic properties. For example, Charles’ law states that volume and temperature are directly related. Gases, therefore, expand when heated at constant pressure. Although gas laws explain how the macroscopic properties change relative to one another, it does not explain the rationale behind it. The kinetic molecular theory is a microscopic model that helps understand what...
02:34
Kinetic Molecular Theory and Gas Laws Explain Properties of Gas Molecules
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2020
The test of the kinetic molecular theory (KMT) and its postulates is its ability to explain and describe the behavior of a gas. The various gas laws (Boyle’s, Charles’s, Gay-Lussac’s, Avogadro’s, and Dalton’s laws) can be derived from the assumptions of the KMT, which have led chemists to believe that the assumptions of the theory accurately represent the properties of gas molecules. The Kinetic Molecular Theory Explains the Behavior of Gases Recalling that gas pressure is exerted by rapidly...
10:18
Molecular Orbital (MO) Theory
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2023
Source: Tamara M. Powers, Department of Chemistry, Texas A&M University This protocol serves as a guide in the synthesis of two metal complexes featuring the ligand 1,1'-bis(diphenylphosphino)ferrocene (dppf): M(dppf)Cl2, where M = Ni or Pd. While both of these transition metal complexes are 4-coordinate, they exhibit different geometries at the metal center. Using molecular orbital (MO) theory in conjunction with 1H NMR and Evans method, we will determine the geometry of these two...
03:51
Molecular Orbital Theory II
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2020
Molecular Orbital Energy Diagrams The relative energy levels of atomic and molecular orbitals are typically shown in a molecular orbital diagram. For a diatomic molecule, the atomic orbitals of one atom are shown on the left, and those of the other atom are shown on the right. Each horizontal line represents one orbital that can hold two electrons. The molecular orbitals formed by the combination of the atomic orbitals are shown in the center. Dashed lines show which of the atomic orbitals...
FAQs
Absolute temperature reflects the average kinetic energy of gas particles. As temperature rises, particles move faster on average, so their collisions with container walls can produce greater pressure when other relevant conditions remain unchanged. This relationship lets chemists connect temperature measurements with particle motion rather than treating temperature as only a macroscopic reading.
Pressure results from particles striking the walls of their container and transferring momentum during collisions. The frequency and effect of these impacts depend on the particles’ motion and the available volume. Consequently, changing temperature or volume changes the pattern of wall collisions, allowing the theory to explain observed pressure changes at the macroscopic scale.
The ideal-gas model assumes that particles occupy negligible volume, move continuously and randomly, exert no intermolecular forces, and collide elastically. These assumptions simplify the connection between particle motion and measurable gas properties. They also establish a reference model against which chemists can recognize situations where particle size or attractions affect real-gas behavior.
For an ideal gas, particle size and intermolecular attractions are treated as insignificant, so pressure, volume, temperature, and amount can be interpreted through the simplified model. Real gases may depart from those predictions when particle size and attractions become important. Comparing the two descriptions helps identify the limits of ideal-gas reasoning.
Begin by identifying which macroscopic variables change: pressure, volume, temperature, or amount of gas. Then use the particle-level assumptions to anticipate how motion, wall collisions, or the number of particles will change. This approach provides a conceptual basis for interpreting gas laws and predicting the direction of a gas response.
Changing volume alters the space available for moving particles and therefore influences how often they encounter the container walls. A reduced volume generally makes collisions occur more frequently, helping explain an increase in pressure when temperature and amount remain appropriately controlled. The model links this observable pressure response to microscopic motion.
The theory provides a particle-level interpretation for relationships among pressure, volume, temperature, and amount of gas. Instead of treating gas laws as isolated equations, students can use the model to explain why measurements change and to compare ideal predictions with real behavior. This connection supports broader chemical reasoning about microscopic causes and macroscopic outcomes.