Question 2.170: A certain closed cell foam used as an insulating material in...

Problems and Solutions on Thermodynamics and Statistical Mechanics

A certain closed cell foam used as an insulating material in houses is manufactured in such a way that the cells are initially filled with a polyatomic gas of molecular weight ∼60. After several years the gas diffuses out of the foam and is replaced by dry air (mean molecular weight ∼ 30 ). Assuming that the insulating property arises largely from the thermal conductivity
of the gas.
Discuss the factors which influence the thermal conductivity of the gas. For each factor make an argument for whether the insulating ability increases or decreases. What is the overall effect upon the insulating ability?

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