How Do You Calculate the Molar Mass of an Unknown Gas?

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Discussion Overview

The discussion revolves around calculating the molar mass of an unknown gas using the Ideal Gas Law, based on a comparison with a known mass of hydrogen gas under the same conditions of temperature and pressure.

Discussion Character

  • Homework-related
  • Mathematical reasoning

Main Points Raised

  • One participant seeks assistance in calculating the molar mass of an unknown gas using a given mass of hydrogen gas.
  • Another participant suggests writing down the Ideal Gas Law for both cases to clarify the solution process.
  • A participant questions whether it is necessary to assume standard temperature and pressure (STP) for the calculations.
  • Another participant argues that the result is independent of temperature, pressure, and volume if ideal gas behavior is assumed, and recommends writing the ideal gas equations to solve the problem.

Areas of Agreement / Disagreement

Participants express differing views on the necessity of assuming STP, indicating that multiple competing views remain regarding the conditions under which the calculations should be made.

Contextual Notes

There is uncertainty regarding the assumptions needed for temperature and pressure in the calculations, as well as the implications of ideal gas behavior on the results.

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

Thanks!
 
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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