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The Gas Laws

The Gas Laws. Kinetic Molecular Theory. Postulates of the Kinetic Molecular Theory of Gases. Gases consist of tiny particles (atoms or molecules) These particles are so small, compared with the distances between them, that the volume (size) of the individual particles can be assumed

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The Gas Laws

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  1. The Gas Laws

  2. Kinetic Molecular Theory Postulates of the Kinetic Molecular Theory of Gases • Gases consist of tiny particles (atoms or molecules) • These particles are so small, compared with the distances between them, that the volume (size) of the individual particles can be assumed to be negligible (zero). 3. The particles are in constant random motion, colliding with the walls of the container. These collisions with the walls cause the pressure exerted by the gas. 4. The particles are assumed not to attract or to repel each other. 5. The average kinetic energy of the gas particles is directly proportional to the Kelvin temperature of the gas

  3. Kinetic Molecular Theory (KMT) AS TEMP. , KE • explains why gases behave as they do • deals w/“ideal” gas particles… 1. …are so small that they are assumed to have zero volume • …are in constant, straight-line motion • …experience elastic collisionsin which no energy is lost • …have no attractive or repulsiveforces toward each other • …have an average kinetic energy (KE)that is proportional to theabsolute temp. of gas (i.e., Kelvin temp.)

  4. Model Gas Behavior All collisions must be elastic Take one step per beat of the metronome Container Class stands outside tape box Higher temperature Faster beats of metronome Decreased volume Divide box in half More Moles More students are inside box Mark area of container with tape on ground. Add only a few molecules of inert gas Increase temperature Decrease volume Add more gas Effect of diffusion Effect of effusion (opening size)

  5. Kinetic Molecular Theory • Particles in an ideal gas… • have no volume. • have elastic collisions. • are in constant, random, straight-line motion. • don’t attract or repel each other. • have an avg. KE directly related to Kelvin temperature. Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem

  6. Real Gases • Particles in a REAL gas… • have their own volume • attract each other • Gas behavior is most ideal… • at low pressures • at high temperatures • in nonpolar atoms/molecules Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem

  7. Properties of Gases Gas properties can be modeled using math. Model depends on: V = volume of the gas (liters, L) T = temperature (Kelvin, K) P = pressure (atmospheres, atm) n = amount (moles, mol) PV = nRT The ideal Gas Law

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