# Gas laws

#### ice888

Two identical vessels A and B of equal volume, V, each, are connected by a narrow tube of negligible internal volume. Initially the whole system is filled with dry air at a pressure of 10^5 Pa and temperature 300K. The total amount of gas present in two vessels is 80.2V moles. Given that the temperature of the vessel B is now raised to 600K, the temperature of A remaining at 300K, what is the new pressure in the system?

could someone help me start off? can't think of what to use... thanks !

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#### whozum

Trusty old Ideal Gas Law looks good to me. You have the initial and final conditions.

#### ice888

i've tried PV=nRT for the final state, but to find P, i need the final value of V and T. Pardon me, is V a constant in this case? and how can i find the final equilibrium temperature?

#### whozum

Well the vessels are identical, so that tells you the volume in each compartment.. it also gives you the volume in each compartmen.

#### whozum

I'm going to bed so I dont want to leave you empty handed. You are given initial pressure in the entire system and the number of moels of gas as well as temperature. You can use this to find the net volume by just plugging into the Ideal Gas Law. Once you ahve that, knowing the chambers are identical, you can say that since the system is closed, the First law of thermodynamics holds and that the heat exchange is equal. This gives you the final equilibrium temperature. From there just plug and chug again into PVnRT to find the final pressure.

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