Homework Help: AvLaw - Which is the correct method of finding moles of gases?

1. Dec 17, 2017

axer

1. The problem statement, all variables and given/known data
1000 L steel storage tank contains 88.5 kg of methane gas, CH4.
Calculate no. of moles.

3. The attempt at a solution
one method= no. of moles=mass/molar mass.
no. of moles= 88500/16.04= 5517.4 moles.

other method= 1 mol= 22.4 liter.
no of moles= 1000 L/22.4L= 44.6 moles.

Please inform me of the correct method, thanks!

2. Dec 17, 2017

The 22.4 L for one mole is only at S.T.P.=Standard temperature and pressure. They did not specify the temperature, but the much bigger factor here is the gas in the container is undoubtedly pressured. Assuming it is at standard temperature (zero degrees Centigrade), you could compute the pressure in atmospheres by taking the ratio of your first answer divided by your second (incorrect answer).

3. Dec 17, 2017

axer

So 5517.4 moles is the correct number of moles? since they didn't specify the temp.

4. Dec 17, 2017

Yes, it is correct, regardless of the temperature. Upon being given the temperature, it would also be possible to compute the pressure. You would find that the gas is highly pressurized, unless it is being kept at very low temperature.

5. Dec 17, 2017

axer

Oh by using the ideal gas law, ok thanks!

6. Dec 18, 2017