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

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In summary, the conversation is about finding the molar mass of an unknown gas given the amount of H2 gas in a sample bulb and the maximum amount of the unknown gas the bulb can hold under the same temperature and pressure. The question asks if the ideal gas law needs to be applied and the response is that it is not necessary, and to simply write and solve the ideal gas equations.
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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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  • #2
Yeah. Write down the Ideal gas law in both the cases. Do you see how to solve it now?
 
  • #3
given the only data in the problem, do i have to assume STP in both?

Thanks!
 
  • #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.
 

1. What is molar mass of a gas?

The molar mass of a gas is the mass of one mole of that gas. It is typically measured in units of grams per mole (g/mol).

2. Why is it important to know the molar mass of a gas?

Knowing the molar mass of a gas is important because it allows us to calculate the number of moles of gas present in a given sample. This is crucial for many scientific calculations and experiments.

3. How is the molar mass of a gas calculated?

The molar mass of a gas can be calculated by dividing the mass of the gas by its volume at STP (standard temperature and pressure). Alternatively, it can also be calculated by using the ideal gas law equation, PV = nRT, where P is pressure, V is volume, n is moles, R is the gas constant, and T is temperature.

4. What is the unit of molar mass?

The unit of molar mass is grams per mole (g/mol).

5. How can I determine the molar mass of an unknown gas?

There are several methods to determine the molar mass of an unknown gas, including using a gas chromatograph or performing ideal gas law experiments. One common method is to use the ideal gas law equation and solve for the molar mass by plugging in known values for P, V, n, R, and T.

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