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Homework Help: HELP PLEASE Molar mass of unknown gas

  1. Jun 24, 2007 #1
    HELP PLEASE!! Molar mass of unknown gas

    Hey, I would really appreciate a little help. I'm kind of confused :( with this question:

    A sample bulb contained 0.712 g of H2 (g) at a certain temperature and pressure. Under the same conditions of temperature an pressure, the bulb can hold 13 g of an unknown gas. What is the molar mass of the unknown mass?? Does anybody know if I have to apply the ideal gal law and how??

    Thank you!!
  2. jcsd
  3. Jun 24, 2007 #2


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    Homework Helper
    Gold Member

    Yeah. Write down the Ideal gas law in both the cases. Do you see how to solve it now?
  4. Jun 24, 2007 #3
    given the only data in the problem, do i have to assume STP in both?

  5. Jun 24, 2007 #4
    No, the result is independent of the temperature, pressure and volume, if we assume ideal gas behaviour.
    Just write the ideal gas equations and solve.
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