Calculating Heat Capacity of Krypton at 90K

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Homework Help Overview

The discussion revolves around calculating the heat capacity of Krypton at a temperature of 90K, focusing on its behavior when adsorbed onto a solid surface. Participants explore the implications of surface area and surface density in the context of a two-dimensional gas model.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning, Assumption checking

Approaches and Questions Raised

  • Participants discuss how to derive the number of moles of Krypton from the given surface area and surface density, questioning the relationship between these quantities. There is exploration of the concept of a 2D gas and its implications for degrees of freedom in energy calculations. Some participants express confusion about the calculations involving surface density and area, while others suggest methods to clarify the approach.

Discussion Status

The discussion is active, with participants providing insights and guidance on how to approach the problem. There is a recognition of the need to consider the unique properties of a 2D gas, and some participants are working through calculations to find the number of moles and specific heat. Multiple interpretations of the problem are being explored, particularly regarding the degrees of freedom and energy distribution.

Contextual Notes

Participants note the constraints of the problem, including the specific temperature and the conditions under which Krypton is adsorbed. There is an emphasis on understanding the implications of the gas being confined to a surface, which affects the calculations of heat capacity.

  • #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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