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Homework Help: Helium balloon problem

  1. May 5, 2010 #1
    Question from my homework. I'm not exactly sure what I am doing wrong, and it is bugging me. I hope this post is in the right forum.

    Imagine that 9.9 g of liquid helium, initially at 4.20 K, evaporate into an empty balloon that is kept at 1.00-atm pressure. What is the volume of the ballon at the following?
    (a) 23.0 K

    (b) 299 K

    After missing the question, help was given, but I can't make sense of it:

    Apply the ideal-gas law to find the volume of the gas at 4.2 K, and a fixed amount of gas to find its volume at the given temperatures.
    Last edited by a moderator: Jul 21, 2014
  2. jcsd
  3. May 6, 2010 #2
    Re: Pressure

    you must have the density at 4.2 the you can calculate the volume at 4.2 . then you can calculate the volume at the other temperatures from the equation
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