Equal amounts (in moles) of helium and neon are each brought separately to the same…

CHEMISTRY · Multi-part · AP · Chemistry · Properties of Substances and Mixtures · Properties of Substances and Mixtures

Problem

Equal amounts (in moles) of helium and neon are each brought separately to the same absolute temperature

T

and allowed to reach equilibrium in identical rigid containers. You may take the molar masses to be

M_{\text{He}}=4\,\text{g\,mol}^{-1}

and

M_{\text{Ne}}=20\,\text{g\,mol}^{-1}

. Assume ideal-gas behavior. (a) Calculate the ratio of the root-mean-square speeds

v_{rms,\text{He}}/v_{rms,\text{Ne}}

. (b) If speed distributions for the two gases were plotted on the same axes, identify which gas would have the broader distribution and explain why. (c) At a speed of

1000\,\text{m\,s}^{-1}

, which gas would have the larger fraction of its particles moving at or above that speed? Justify your answer using properties of the distributions.

Related theory

Gaseous State
States of Matter
Mole concept
Some Basic Concepts of Chemistry
Mole Concept and Molar Masses

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