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# Gas laws query

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1. I am pretty bad at physics so if this turns out to be really simple, apologies.
So obviously don't tell me the answer as such but can someone tell me where to start with this question:

An ideal gas at 22C is in cylinder 0.20m^3 at pressure 1.6x10^6 Pa (130 mol calculated previously, along with molar mass 4.3x10^-2 kgmol^-1 and density 28kgm^3).

Now the cylinder is taken to area of temp. -50C and pressure 3.6x10^4. A valve is opened, find the mass when it reaches equilibrium with surroundings.

Basically my main question is what does it mean by equilibrium? If you did that with any can all the gas just leaks out and ur left with nothing. Since it asks for mass I assumed it's the kinetic model equation but you're not given any velocities
2. I think it's to do with balancing the pressures and the temperature. Do you have the answer to this? I am struggling to find the answer too, but I reached the point where I know what the pressure and temperature in the room will be after the valve has been opened...
3. (Original post by Toasticide)
I am pretty bad at physics so if this turns out to be really simple, apologies.
So obviously don't tell me the answer as such but can someone tell me where to start with this question:

An ideal gas at 22C is in cylinder 0.20m^3 at pressure 1.6x10^6 Pa (130 mol calculated previously, along with molar mass 4.3x10^-2 kgmol^-1 and density 28kgm^3).

Now the cylinder is taken to area of temp. -50C and pressure 3.6x10^4. A valve is opened, find the mass when it reaches equilibrium with surroundings.

Basically my main question is what does it mean by equilibrium? If you did that with any can all the gas just leaks out and ur left with nothing. Since it asks for mass I assumed it's the kinetic model equation but you're not given any velocities
I think it just wants the mass of 0.20 m^3 of the ideal gas at -50 degrees C and 3.6x10^4 Pa

I.e. it'll be at equilibrium when the pressure and temperature have equalised with the new environment - but the gas bottle will have the same volume
4. (Original post by Joinedup)
I think it just wants the mass of 0.20 m^3 of the ideal gas at -50 degrees C and 3.6x10^4 Pa

I.e. it'll be at equilibrium when the pressure and temperature have equalised with the new environment - but the gas bottle will have the same volume
Surely it would be -14 degrees C and 8.18 x 10^5 Pa in order to get the new values once the valve is opened, because the conditions must equalise with the environment?
5. (Original post by Uni12345678)
Surely it would be -14 degrees C and 8.18 x 10^5 Pa in order to get the new values once the valve is opened, because the conditions must equalise with the environment?
OP doesn't say what the volume of the new environment is afaict - I'd assumed it was effectively limitless (perhaps the gas bottle has been transported to the planet Zog), I still can't see where the information you've used to get those values comes from tbh - but if there's a fixed volume of the new environment you'd have to find the new equilibrium.
6. (Original post by Joinedup)
OP doesn't say what the volume of the new environment is afaict - I'd assumed it was effectively limitless (perhaps the gas bottle has been transported to the planet Zog), I still can't see where the information you've used to get those values comes from tbh - but if there's a fixed volume of the new environment you'd have to find the new equilibrium.
But surely since the environment of the cylinder is different to the environment of the new environment... so the pressure and temperature would resolve to the midpoints?? Idk
7. sadly this is part of a homework task so i dont have the answer yet, and shan't for a while. I'm asking some friends too and they'll tell me the answer if they get it. I'll share in case anyone wonders about it
8. okay something i noticed (friends havent done it yet, typical) is instead of using the ideal gas equation, you use P1V1/T1=P2V2/T2
where the final pressure (equilibrium) is atmospheric pressure.
It would make sense as you're given the density and by then finding the volume you can find the mass
In the end i got 0.1996 kg from those two formulae since temperature is constant at 223K.

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