Recent content by Zeppos10

The question: wouldn't temp. change (decrease) also for the ideal case? After all the expanding gas will be doing work against the pressure that is being created in the right chamber? Am I missing something? My answer: yes the LHS-gas will do some work on the RHS-gas, but the RHS-gas will...

Hello you all: first I assume a closed non-reactive system with n=constant, the system being an ideal gas. lets assume H(U,p,V)=U+pV by definition and let's assume that for an ideal gas, U is a function of T only, hence H=H(T,p,V). However, for an ideal gas pV=nRT, hence of the variables...

see: "Extensive Quantities in Thermodynamics" DOI= 10.1088/0143-0807/35/3/035017 (published in 2014)

when the carnot cycle has come full circle, it returns to the same state, hence dU=0. During the cycle, this is different ie dU ><0.

I agree with Chestermiller, except that it would be better to adhere to the same sign convention for all work (and heat) terms: work in >0, work out <0. Then the relationship becomes DH=Q+Ws.

The difference between U and H is pV. This pV term stands for the energy of displacement, equal to the work needed to displace the atmosphere from the space occupied by the system: p is thus the atmospheric pressure. For all systems where internal and atmospheric pressure are equal, one can...

Discussions in this forum repeat themselves without much progress (my difficulty). The question raised by "outrageous" was: So can I say work done on a system at constant pressure is a state function ? The answer to this question is yes. The state variable (the use of the word "function" has no...

in the preceding discussion no distinction is made between the pressure of the system and the pressure of the atmosphere. Further, no distincion is made between work done by/on the atmosphere and other work done by an external agent (called technical work). There is also work done on/by the...

see also attachment at https://www.physicsforums.com/showthread.php?t=88987&referrerid=219693

In the above structure and some specifics are lacking: I will take the response by ACUT to elaborate: But how do you connect ∆H=Q with H=U+pV ?? we know ∆U = Q + W = Q + W' + W" where W" = useful work = shaft work = technical work. W' is work done against the atmosphere = -p'∆V, if p' is the...

shouln't you first write out the reaction-equation ?? I wonder which textbook you are using ??

Hello Bert: you are probably retired from PF by now but the issue might be interesting for others too: we take a system consisting of 1 kind of species present (we take helium). internal energy U is an extensive quantity so we need 1+2=3 variables to know it. But U=n(3/2)RT, so here two...

the proper definition of an extensive quantity is: if there is a system with extensive quanty X' and another system with X" then the two systems together has property X, with X=X'+X". (the property is additive). This is independent of the existence of a function X(a,b,c) where a b and c are also...

Enthalpy is also defined for solids and liquids, indeed for any system: how do you define p as in H=U+pV there ?

LS: as long as no distinction is made between the internal pressure an the external pressure this discussion will go the same way any piston would: nowhere. The subject is adressed in the attachment zeppos10 placed elsewhere in this forum...