What is the ratio of the average molecular kinetic energy of uf6

  1. Connecting Gas Properties to Kinetic Theory of Gases
  2. The two isotopes of uranium, ""^238 U and ""^235 U, can be separated by effusion of the corresponding UF_6 gases. What is the ratio (in the form of a decimal) of the RMS speed of ""^238 UF_6 to that of ""^235 UF_6 at constant temperature?
  3. 9.14: Kinetic Theory of Gases


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Connecting Gas Properties to Kinetic Theory of Gases

https://chem.libretexts.org/@app/auth/3/login?returnto=https%3A%2F%2Fchem.libretexts.org%2FBookshelves%2FPhysical_and_Theoretical_Chemistry_Textbook_Maps%2FSupplemental_Modules_(Physical_and_Theoretical_Chemistry)%2FPhysical_Properties_of_Matter%2FStates_of_Matter%2FProperties_of_Gases%2FKinetic_Theory_of_Gases%2FConnecting_Gas_Properties_to_Kinetic_Theory_of_Gases Expand/collapse global hierarchy • Home • Bookshelves • Physical & Theoretical Chemistry • Supplemental Modules (Physical and Theoretical Chemistry) • Physical Properties of Matter • States of Matter • Properties of Gases • Kinetic Theory of Gases • Connecting Gas Properties to Kinetic Theory of Gases Expand/collapse global location \( \newcommand\) • • • • • • • • • • • • • • • • • • • • When examining the ideal gas laws in conjunction with the kinetic theory of gases, we gain insights into the behavior of ideal gas. We can then predict how gas particles behaviors such as gas molecular speed, effusion rates, distances traveled by gas molecules. Graham's Law, which was formulated by the Scottish physical chemist Thomas Graham, is an important law that connects gas properties to the kinetic theory of gases. Introduction The Kinetic Molecular Theory states that the average energy of molecules is proportional to absolute temperature as illustrated by the following equation: \[e_K=\dfracT\] where • e k is the average translation kinetic energy, • R is the gas constant, • N A is Avogadro's number, and • T is temperat...

The two isotopes of uranium, ""^238 U and ""^235 U, can be separated by effusion of the corresponding UF_6 gases. What is the ratio (in the form of a decimal) of the RMS speed of ""^238 UF_6 to that of ""^235 UF_6 at constant temperature?

I got about #0.9957#. I know it doesn't give you a temperature to work with, but it doesn't really matter because you're at constant temperature. The root-mean-square (RMS) speed of a freely-moving gas following Maxwell-Boltzmann statistics (in the absence of an external field) is given by: #v_(RMS) = sqrt((3RT)/M) = sqrt((3k_BT)/m)#, where #R# is the universal gas constant, #k_B# is the Boltzmann constant, #M# is the molar mass in #"kg/mol"#, and #m# is the mass in #"kg"#. Use whichever version you want, and you would get the same result. I will use the second version. Thus: #(v_(RMS)(""^(238) UF_6))/(v_(RMS)(""^(235) UF_6)) = sqrt((3k_BT)/m_(""^238 UF_6))/sqrt((3k_BT)/m_(""^235 UF_6))# #= sqrt(m_(""^235 UF_6)/m_(""^238 UF_6))# You can also see that this follows Graham's law of effusion, i.e. the ratio of the gas speeds is equal to the ratio of their rates of effusion. Since the masses are in a ratio, we can use arbitrary units for them, rather than #"kg"#, if we wanted. Remember to use the isotopic masses, i.e. #m_(""^238 U) = "238.05078826 amu"# #m_(""^235 U) = "235.0439299 amu"# #m_(""^19 F) = "18.99840322 amu"# Therefore, we get: #color(blue)((v_(RMS)(""^(238) UF_6))/(v_(RMS)(""^(235) UF_6))) = sqrt(("235.0439299 amu" + 6 xx "18.99840322 amu")/("238.05078826 amu" + 6 xx "18.99840322 amu"))# #= color(blue)(0.9957)# So, the separation process is apparently very precise... #""^238 "UF"_6(g)# is only #0.43%# slower than #""^235 "UF"_6(g)#.

9.14: Kinetic Theory of Gases

\( \newcommand\) times the gas constant R. The video below demonstrates the relationship between molar kinetic energy and temperature. The demonstration highlights the fact that a higher temperature means a higher molar kinetic energy. When food coloring is placed into water of different temperatures, it behaves differently. Food coloring in hot water is rapidly dispersed because of its high molar kinetic energy/temperature. The cold water on the other hand, has a low molar kinetic energy and therefore the food color spreads slowly through it.