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Measuring the Density of Air

  1. Mar 12, 2016 #1
    1. The problem statement, all variables and given/known data
    Measure the density if air at normal atmospheric pressure. You can use the following equipment:

    One scale with an accuracy of 0.01g
    Two empty glas bottles (≈0,33 liter each)
    One big bowl with water
    One cork with a valve and a vacuumpump

    2. Relevant equations
    Not knowing how to solve this problem I am not sure which equations should be used, but the following could be relevant:
    Density: ρ=m/V (1)
    Ideal Gas equation: pV=nRT =NkT (2)
    Buoyant Force: F=ρgV (3)

    3. The attempt at a solution
    My first thought was that the exact volume of the bottles can be measured by measuring the weight of the water which fit into them and then by knowing the density of water the volume is obtained. Then, we can meausre the weight of an empty bottel with air in it and without. From this, the mass of the air inside the bottles is obtained and the density of the air is achieved. However, I feel like this is a bit to simple. I don't have the equipment to try this at home. Do you think think this solutions works? Or do you have other ideas?

    Thank you for your help! :)
     
  2. jcsd
  3. Mar 12, 2016 #2

    Orodruin

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    Why do you think it is too simple?
     
  4. Mar 13, 2016 #3
    I thought the mass of the air was too small to be measured, but now I realised that m = 1,293*0,00033 ≈0,43 g.
    So maybe this is the solution?
     
  5. Mar 13, 2016 #4

    Orodruin

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    Yes, it should be enough to at least give you a quite rough estimate.
     
  6. Mar 14, 2016 #5
    Well, in that case the problem is solved. Thank you very much! :)
     
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