Ideal Gas law understanding

[Arve]

Hi,
I have a problem where I am to calculate the temperature inside a container after releasing some of the gas (N2) out from the container itself.

To calculate the temperature (T2) I am given the temperature before releasing the gas (T1), and also the pressure inside the container before (p1) and after (p2).

First i though i might be able to use (p1/T1 = p2/T2).,

However, with this I am just ignoring the parameter n, number of molecules, and I am unsure if this is the correct method to use. (pV = nRT)

 

Any help in explaining how to approach this would be much appreciated. 

[exchemist]

47 minutes ago, Arve said:

Hi,
I have a problem where I am to calculate the temperature inside a container after releasing some of the gas (N2) out from the container itself.

To calculate the temperature (T2) I am given the temperature before releasing the gas (T1), and also the pressure inside the container before (p1) and after (p2).

First i though i might be able to use (p1/T1 = p2/T2).,

However, with this I am just ignoring the parameter n, number of molecules, and I am unsure if this is the correct method to use. (pV = nRT)

 

Any help in explaining how to approach this would be much appreciated. 

Well you are right that if you change n then you can't just use these ratios. There must some other information given, though. What is it?  

[Arve]

Thanks for the reply @exchemist.

So the actual task that I have is to design a calculator which gives the following outputs: Temperature on the gas after bleeding of the gas, temperature on the container after bleeding of the gas. 

 

These are the factors given to me: Temperature before, pressure before and after, temperature of the surroundings, volume of the container (length and width), thickness of the wall, thermal conductivity of the material of the container. 

 

I have been working on this problem for a while, but as i mentioned I am not sure what I am missing here. What information are you missing that should be provided here? 

 

Thanks for the help! 

 

[exchemist]

6 minutes ago, Arve said:

Thanks for the reply @exchemist.

So the actual task that I have is to design a calculator which gives the following outputs: Temperature on the gas after bleeding of the gas, temperature on the container after bleeding of the gas. 

 

These are the factors given to me: Temperature before, pressure before and after, temperature of the surroundings, volume of the container (length and width), thickness of the wall, thermal conductivity of the material of the container. 

 

I have been working on this problem for a while, but as i mentioned I am not sure what I am missing here. What information are you missing that should be provided here? 

 

Thanks for the help! 

 

Aha. So you have been given V. You didn't mention that before. 

And when you say a calculator, what data would you input to it in order to get the outputs you describe? 

[Arve]

23 minutes ago, exchemist said:

Aha. So you have been given V. You didn't mention that before. 

And when you say a calculator, what data would you input to it in order to get the outputs you describe? 

Yes that is correct, I have the volume. My mistake. 

The data I have to input are the one I mentioned, Temperature before, pressure before and after, temperature of the surroundings, volume of the container (length and width), thickness of the wall, thermal conductivity of the material of the container. 

Is there any specific data that you see are missing here, that will help solve for the new temperature inside the container, that in a normal day-to-day situation would be easily available? 

Right now I am not focusing on the temperature loss from convection over time. I feel like I first need to figure out how to account for the variable "n". 

[exchemist]

16 minutes ago, Arve said:

Yes that is correct, I have the volume. My mistake. 

The data I have to input are the one I mentioned, Temperature before, pressure before and after, temperature of the surroundings, volume of the container (length and width), thickness of the wall, thermal conductivity of the material of the container. 

Is there any specific data that you see are missing here, that will help solve for the new temperature inside the container, that in a normal day-to-day situation would be easily available? 

Right now I am not focusing on the temperature loss from convection over time. I feel like I first need to figure out how to account for the variable "n". 

Do you know how much gas is bled off, or is the only information you have for the "after" state the pressure?

 

Edited August 2, 2021 by exchemist

[Arve]

5 minutes ago, exchemist said:

Do you know how much gas is bled off, or is the only information you have for the "after" state the pressure? 

No I do not know how much gas is bled off. 

[exchemist]

14 minutes ago, Arve said:

No I do not know how much gas is bled off. 

Hmm. Is this presented as a problem involving the ideal gas equation, or could it be an energy problem? (I'm thinking work is done against atmospheric pressure in bleeding gas off.) 

P.S. I need to run some errands now. Maybe someone will come along who is less rusty on this while I'm away. 

 

Edited August 2, 2021 by exchemist

[Arve]

3 minutes ago, exchemist said:

Hmm. Is this presented as a problem involving the ideal gas equation, or could it be an energy problem? (I'm thinking work is done against atmospheric pressure in bleeding gas off.) 

It may for sure be an energy problem over a problem that involves the ideal gas equation. Maybe that is the reason why I am stuck?
I will try to look more into this, maybe it might be good to walk away from the ideal gas equation completely. 

[Bufofrog]

4 hours ago, Arve said:

I have a problem where I am to calculate the temperature inside a container after releasing some of the gas (N2) out from the container itself.

You were also supplied the thickness of the wall and the thermal conductivity of the wall which seems to indicate that there is a time component in the question, or this is superfluous information.  Could you supply a screen shot of the actual problem?

[joigus]

11 minutes ago, Bufofrog said:

You were also supplied the thickness of the wall and the thermal conductivity of the wall which seems to indicate that there is a time component in the question, [...]

Exactly what I was thinking, besides the volume thing.

[John Cuthber]

I think you are in this territory.
https://en.wikipedia.org/wiki/Adiabatic_process#Ideal_gas_(reversible_process)

[exchemist]

8 minutes ago, John Cuthber said:

I think you are in this territory.
https://en.wikipedia.org/wiki/Adiabatic_process#Ideal_gas_(reversible_process)

Indeed. I notice that the gas, interestingly, is specified as being nitrogen - which means that Cp and Cv are known....... 

[John Cuthber]

And that Cp/Cv is 7/5 or whatever.

Edited August 2, 2021 by John Cuthber

[studiot]

On 8/2/2021 at 9:41 AM, Arve said:

So the actual task that I have is to design a calculator which gives the following outputs: Temperature on the gas after bleeding of the gas, temperature on the container after bleeding of the gas. 

 

These are the factors given to me: Temperature before, pressure before and after, temperature of the surroundings, volume of the container (length and width), thickness of the wall, thermal conductivity of the material of the container. 

 

I have been working on this problem for a while, but as i mentioned I am not sure what I am missing here. What information are you missing that should be provided here? 

Here are example calculations for the different circumstances of expansion.

If you are designing a calculator is this a physics/chemistry or computing project ?

We cannot do the question for you but can offer more help about the Thermodynamics if you are studying computing and vice versa.

Note the examples assume a monatomic gas, I will leave you to suggest which of these calculations is appropriate for your circumstances and what difference if any using nitrogen makes.

We can then discuss this further.

Hopefully you realise that we work in degrees Kelvin in Thermodynamics.

[Arve]

14 hours ago, studiot said:

Here are example calculations for the different circumstances of expansion.

If you are designing a calculator is this a physics/chemistry or computing project ?

We cannot do the question for you but can offer more help about the Thermodynamics if you are studying computing and vice versa.

Note the examples assume a monatomic gas, I will leave you to suggest which of these calculations is appropriate for your circumstances and what difference if any using nitrogen makes.

We can then discuss this further.

Hopefully you realise that we work in degrees Kelvin in Thermodynamics.

This is a computing project where I am designing the project in matlab. However it is the physics/chemistry aspect that i struggle with. 

I am not expecting the answer to anything and I am very happy with the help that I have received so far. 

I will take a closer look in the next week and try to see if I can come up with a solution to my problem based on the information I have now. And hopefully then you help to verify if what I have discovered are correct or not.