1 / 9

Ideal Gases and the Compressibility Factor

A high pressure, molecules are more influenced by repulsive forces. V real > V ideal  Z > 1. The effect of molecular attraction causes: V real < V ideal  Z < 1. Ideal Gases and the Compressibility Factor. 1 mol, 300K for various gases. Lower temperatures

stephanie-hull
Download Presentation

Ideal Gases and the Compressibility Factor

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. A high pressure, molecules are more influenced by repulsive forces. Vreal > Videal  Z > 1 The effect of molecular attraction causes: Vreal < Videal  Z < 1 Ideal Gases and the Compressibility Factor 1 mol, 300K for various gases

  2. Lower temperatures Little thermal motion of molecules Attractive forces dominate: Vreal < Videal  Z < 1 Higher temperatures More influenced by repulsive forces: Vreal > Videal  Z > 1 Effect of Pressure on Compressibility Factor CH4, various temperatures

  3. Comparing Various Equations of State Ethane, 400K van der Waals Redlich-Kwong Peng-Robinson Solid line – experimental

  4. Ammonia B2V = -0.142 dm3 mol-1 at 373 K Ideal gas 1.000 Z 373 K slope = B2P(T) = B2V(T)/RT 0.998 0.1 0 P / bar Second Virial Coefficient and Intermolecular Potentials The second virial coefficient is the most important. Can be determined by plotting Z vs. P.

  5. The effect of temperature At high T B2V increases Boyle temperature: Temperature at which B2V(T) = 0. Repulsive and attractive interactions cancel and gas behaves ideal

  6. The Lennard-Jones Potential Contributions: Dipole-dipole (including H-bonding) Induced dipole London dispersion attraction The short range 1/r12 repulsive term The long range 1/r6 attractive term u(r)/ε 0 ε r/σ 0 1 2 3

More Related