Finding the gas based off of mass

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Homework Help Overview

The discussion revolves around identifying a gas based on its average kinetic energy and momentum squared of a single molecule. Participants are analyzing the relationship between these quantities and the mass of the gas molecule, exploring the implications of their calculations.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning, Assumption checking

Approaches and Questions Raised

  • Participants attempt to derive the mass of the gas molecule using kinetic energy and momentum equations. There are discussions about potential typos in the equations and the correctness of the mass calculations. Questions arise about the relationship between the computed mass and known atomic masses, as well as how to identify the gas based on the calculated molecular weight.

Discussion Status

The conversation is ongoing, with participants providing insights and corrections to each other's calculations. Some suggest possible gases based on the computed molecular weight, while others express uncertainty about the identification process. There is a recognition of the need for additional information to narrow down the possibilities.

Contextual Notes

Participants note the constraints of the problem, including the lack of explicit information about the gas and the challenge of identifying it among common gases. The discussion also touches on the significance of molecular weight in determining the identity of the gas.

  • #31
mk9898 said:
Thanks for your expertise. Just to remove any doubt I have two questions: 1) how is the division from the mass/proton mass = atomic weight? That would just be a scalar. 2) How does one find the total amount of the protons of an element?
The only information we had was the molecular weight. You asked a good question, but other than by looking at the periodic table, I don't know of a simple experiment that will tell you what the atomic number (number of protons) is given the atomic weight.
 
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  • #32
Yea apologies I meant molecular weight. But molecular weight/proton weight = atomic weight? How can that be?
 
  • #33
mk9898 said:
Yea apologies I meant molecular weight. But molecular weight/proton weight = atomic weight? How can that be?
We computed the number of neutrons plus protons. (molecular weight). Since they both have very nearly the same mass, the only thing we knew is that the sum of the neutrons and protons was 83(1.67 E-27) kg. There was no info as to whether we had 40 protons or 41 or 42, etc. Usually the number of protons and neutrons in an atom are about equal, plus or minus one or two or so. ## \\ ## The quickest way to determine the number of protons is to identify the chemical properties of the material, so that you know what the molecule or atom is, and then simply look it up in the periodic table. Experiments with molecular dynamics determine the mass (molecular weight), but these experiments do not give any info on the number of protons.
 
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  • #34
Ok I understand now thank you. I just watched a video that gave some more background on the subject. Thank you a lot for your effort!
 
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