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Homework Help: Air Bubbles

  1. Oct 1, 2006 #1
    Ok heres my problem:

    When I put a piece metal in a graduated cylinder filled with water to measure the metal's volume by "water displacement" I see air bubbles trapped under the metal. How do the air bubbles affect the density, mass and volume of the metal piece? Thanks. Need quick answer.

    I was thinking that since air bubbles are light than the water, they would kind of like "float" and therefore push the metal piece upward. But I'm not sure if that affects the volume of the metal piece at all.

    I was also thinking that since air do have volume, then it might contribute to an increase in the volume reading of the metal piece, and that without the air bubbles, the volume reading would be definite.
  2. jcsd
  3. Oct 1, 2006 #2
    How much metal were you using and what graduation was the graduated flask if its small enough you might be able to disregard the bubbles. The mass would not be effected becasue mass is the amount of matter in an object. Density is mass/volume. The density may fluctuate depending on how a) the volume of liquid and b) the mass of metal used. The bubbles will change the volume of liquid but again it all depends on how much metal you have, if it was say a 5cm 1/2 gram piece there would only be a few bubbles. If you know how many mL of liquid there are in the graduated cylinder it will help to see if the bubbles will have a notable change in volume. Hope this helps
  4. Oct 1, 2006 #3


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    The air bubbles on the metal may be adsorbed ambient air, assuming that it is not reacting with the solution in the graduated cylinder. It would contribute to displacing the volume, however its mass is certainly smaller then that of the metal. How would this affect the density which would be calculated through this method, for the metal itself?
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