Gen Physics HW Help: Ideal Gas Law and Temperature Change

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SUMMARY

The discussion focuses on calculating the fraction of air molecules that must be expelled from a house as the temperature increases from 16°C to 20°C, using the Ideal Gas Law. The relevant equation is PV = NkT, where N represents the number of molecules, k is the Boltzmann constant, and T is the absolute temperature in Kelvin. The solution indicates that N2/N1 equals T2/T1, leading to the conclusion that N2 equals 0.80N1, resulting in a fraction of 0.0136 of air molecules needing to be pushed outside. The calculation emphasizes the importance of using absolute temperature for accuracy.

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  • Understanding of the Ideal Gas Law (PV = NkT)
  • Knowledge of temperature conversion to Kelvin
  • Familiarity with the concept of pressure in gas laws
  • Basic algebra for manipulating equations
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  • Learn about temperature conversion methods, especially to Kelvin
  • Explore the implications of pressure changes in gas behavior
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Students studying physics, particularly those focusing on thermodynamics and gas laws, as well as educators seeking to clarify concepts related to temperature changes and gas behavior.

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HW Help: Absolute temp and ideal gas law

Homework Statement


What fraction of the air molecules in a house must be pushed outside while the furnace raises the inside temperature from 16C to 20C? The pressure does not change since the house is not 100% airtight.


Homework Equations


PV=NkT
PV/T=PV/T
?


The Attempt at a Solution


NkT=NkT? N2/N1 = T2/T1. N2 = .80N1. Answer provided is .0136. I can't figure how that answer comes about. Help would be grateful. Thanks.
 
Last edited:
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You need to take the temperature ratio in degrees Kelvin i.e. T=0 should be absolute zero.
 
Assuming the pressure inside the house does not change, your formula is correct. It's OK to solve in degrees C, the answer is relational.
 

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