Calculating Heat Capacity of Krypton at 90K

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SUMMARY

The discussion focuses on calculating the heat capacity of Krypton at 90K when adsorbed onto a solid surface. The specific heat at constant volume (Cv) for this 2D gas is determined using the equation U = nRT, where n is the number of moles derived from the surface area and surface density. The participants clarify that the degrees of freedom for the 2D gas is 2, leading to Cv equating to the gas constant R. The final calculated value for Cv is approximately 1.035 x 10^-4 J/K, which aligns with theoretical expectations for a 2D gas.

PREREQUISITES
  • Understanding of specific heat and its calculation
  • Familiarity with the ideal gas law and its applications
  • Knowledge of degrees of freedom in thermodynamics
  • Basic principles of statistical mechanics, particularly equipartition of energy
NEXT STEPS
  • Study the equipartition theorem and its implications for different dimensional gases
  • Learn about the specific heat capacities of various gases, focusing on 2D versus 3D systems
  • Explore the concept of surface density and its role in thermodynamic calculations
  • Investigate the differences between constant volume and constant pressure specific heat capacities
USEFUL FOR

Students and professionals in physics and chemistry, particularly those studying thermodynamics, statistical mechanics, and material science, will benefit from this discussion.

  • #31
davedavidson said:
Sorry if I’ve missed something but why are you using specific heat at constant volume? The volume isn't constant; the question states that the gas is free to move along the surface. Wouldn’t it be c at constant pressure?

Well, the surface area is of a fixed size. The atoms are constrained to that fixed-size surface. It's the 2D equivalent to the 3D constant volume case.

I suppose that, notationally, the constant should be CA, for constant area!
 
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  • #32
davedavidson said:
Sorry if I’ve missed something but why are you using specific heat at constant volume? The volume isn't constant; the question states that the gas is free to move along the surface. Wouldn’t it be c at constant pressure?

The problem states that the atoms of the 2D gas are free to move on the surface.

The particles of a normal gas in 3 dimension move freely inside the container. The volume of the gas is defined as the volume of the container.

The particles of the 2D gas move freely on a certain surface. The area of the surface plays the role of volume.


ehild
 

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