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

  • Context: Chemistry 
  • Thread starter Thread starter axer
  • Start date Start date
  • Tags Tags
    Gases Method Moles
Click For Summary
SUMMARY

The correct method for calculating the number of moles of methane gas (CH4) in a 1000 L steel storage tank is to use the formula for moles, which is mass divided by molar mass. In this case, the calculation yields 5517.4 moles (88.5 kg / 16.04 g/mol). The alternative method using the volume of gas at standard temperature and pressure (22.4 L/mol) results in an incorrect value of 44.6 moles, as this method is only valid under STP conditions. The discussion emphasizes that the gas is likely under pressure, which affects the calculations.

PREREQUISITES
  • Understanding of Avogadro's Law
  • Knowledge of the Ideal Gas Law
  • Familiarity with molar mass calculations
  • Concept of Standard Temperature and Pressure (STP)
NEXT STEPS
  • Study the Ideal Gas Law and its applications
  • Learn about the effects of pressure on gas volume
  • Review calculations involving molar mass for various gases
  • Explore scenarios involving gases under non-STP conditions
USEFUL FOR

Chemistry students, educators, and professionals involved in gas calculations and thermodynamics will benefit from this discussion.

axer
Messages
35
Reaction score
4

Homework Statement


Based on your understanding of Avogadro's law.
1000 L steel storage tank contains 88.5 kg of methane gas, CH4.
Calculate no. of moles.

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!
 
Physics news on Phys.org
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).
 
Charles Link said:
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).
So 5517.4 moles is the correct number of moles? since they didn't specify the temp.
 
axer said:
So 5517.4 moles is the correct number of moles? since they didn't specify the temp.
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.
 
Charles Link said:
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.
Oh by using the ideal gas law, ok thanks!
 
  • Like
Likes   Reactions: Charles Link
Your first answer was correct. How could you doubt it?
In this and other questions you have shown yourself to have some grasp but were easily distracted and confused by irrelevancies. Things that were related to a question but made you miss a point.
So having been partially successful and activated it is a good time, I recommend, to go back and do some revision in order to get the concepts fixed securely in your mind. :smile:
 
  • Like
Likes   Reactions: axer

Similar threads

  • · Replies 3 ·
Replies
3
Views
3K
  • · Replies 3 ·
Replies
3
Views
2K
  • · Replies 4 ·
Replies
4
Views
3K
  • · Replies 1 ·
Replies
1
Views
8K
  • · Replies 2 ·
Replies
2
Views
9K
  • · Replies 1 ·
Replies
1
Views
32K
  • · Replies 2 ·
Replies
2
Views
11K
Replies
4
Views
4K
  • · Replies 6 ·
Replies
6
Views
3K
  • · Replies 8 ·
Replies
8
Views
4K