[Borek]

Q must be zero

the heat that flows into A to warm it is balanced by the heat that flows out from B to cool it

Q = (+q) + (-q) = 0

[mjc123]

froggarana, we don't seem to be getting far here. May I suggest that you try posting your original question on Physics Forums: www.physicsforums.com. They have some members who are very good on thermodynamics, from a physics rather than a chemistry perspective, especially one guy called chestermiller, whose opinion I would trust absolutely. I promise you that if he takes your side on this, I will grovellingly apologise to you. But till then I stick to my guns.

[froggarana]

borek, the book makes no mention of heat leaving the system, if they had Q=0 i would not be making a first law argument but would be saying no heat crosses the system boundary ( which is quite different from the net transfer is zero )
In the preface they say they wrote the book because many students find thermo difficult and confusing, in my view they are helping to propagate the very common error that gasses must cool on expanding or throttling 

mjc123, thank you for your suggestion, i will try that forum, other forums have produced nothing useful, eg no replies or the physicist at " ask a physicist " who believes an ideal gas cooling on expanding is part of the definition of ideal gas
But i would like , if i may, to reserve all grovelling rights to myself, just in case. 

[Arkcon]

Good.  We're done here.

*Topic Locked*