What Affects the RMS Speed Difference Between Helium Atoms and Molecules?

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SUMMARY

The discussion focuses on the calculation of the root mean square (RMS) speed of helium atoms and molecules when heat is added, resulting in a 50% increase in speed. The relevant equation used is RMS = (3kT/m)^(1/2), where 'k' is the Boltzmann constant, 'T' is the temperature, and 'm' is the mass of the gas. It is established that helium is a monatomic gas, and thus the RMS speed of helium atoms is not the same as that of diatomic molecules, which is a critical distinction for accurate calculations of pressure changes.

PREREQUISITES
  • Understanding of the ideal gas law and its implications.
  • Familiarity with the concept of root mean square speed in kinetic theory.
  • Knowledge of the Boltzmann constant and its role in thermodynamics.
  • Basic understanding of atomic and molecular mass calculations.
NEXT STEPS
  • Study the derivation of the RMS speed formula in kinetic theory.
  • Learn about the properties of monatomic versus diatomic gases.
  • Explore the implications of temperature changes on gas pressure using the ideal gas law.
  • Investigate the behavior of helium under varying thermal conditions and its applications in real-world scenarios.
USEFUL FOR

This discussion is beneficial for physics students, educators, and anyone interested in thermodynamics and the behavior of gases, particularly in understanding the differences between atomic and molecular gas properties.

barrylwires
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Homework Statement


Heat is added until the rms speed of a helium atom has increased 50%. Find new pressure. (Not all parameters given.)


Homework Equations


rms = (3kT/m)1/2
mass of molecule = mass of mole/NA
Then, mass of helium molecule is 6.6x10-26kg

The Attempt at a Solution


Question: Is rms speed of a helium molecule the same as the rms speed of an atom. Yes, because the atoms make up the molecule? No, helium is diatomic (right?) and so that has to be taken into account??
 
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