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Homework Help: Thermodynamics and Gas expansion

  1. Jan 16, 2006 #1
    Here's the Question:
    In a Classroom there are 50 rows of students. A container of N20 (laughing gas) was opened at the front row and tear gas (molar mass 240 gm/mole) was opened simultaneously at the rear of the room. Which row of students will be the first to be laughing with tears in their eyes? mm(N)=14 & mm(O)=16
    I thought I could solve it by using KE=3/2 KT and then after finding out the kinetic energy... substitute and solve for Velocity in KE=1/2 mv²
    However.. in the problem it doesn't say anything about the temperature in the room so I dont know if i should assume that it's room temperature or if there's another way to solve this... Any help is appreciated.
  2. jcsd
  3. Jan 17, 2006 #2


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    I think it's safe to assume the temperature is uniform throughout the room. You only need the relative thermal speeds of the molecules to determine where the two "diffusion fronts" will meet.
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