1i also had the same doubt for a looooong period...but i got that myself....both are correct...(only change lies in sign convention)
In Thermodynamics (physics) , work done by the system is taken positive
but in Thermochemistry, work done by the system is negative (as per my book)
Why are both the signs different? or is there any mistake in my book?
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11 Answers
23in physics thermo , work done by gas is simply taken as simply ∫F.ds
in chem thermo,
when work is done by gas it loses its internal energy hence when work is done by gas it taken as negative ,
now q = U + w ko change karna padega, because we changed the convention of sign of w ,
so eqn in chem is q = U - w
111Actually I had a discussion on this topic with one of my senior.
And after collecting from him and various sources I have reached the conclusion that our basic aims in physics and chemistry differ a lot.
In chemistry we deal with the change in internal energy of the system which is occurring either due to heat loss or by work.
In physics we hardly reckon any change in internal energy or any of that crap.We deal with the mechanical work or the mechanical advantage we can get out of machines.(In chemistry we are concerned about the reaction taking place in the calorimeter or ay of that sort)
ENERGY IS ANALOGOUSLY THE AMOUNT OF WORK E ARE CAPABLE OF DOING.
HENCE OUR VIEW OF TAKING THE SYSTEM CHANGES.
I THINK I AM CLEAR ENOUGH.
1I don't understand what you mean by this
ENERGY IS ANALOGOUSLY THE AMOUNT OF WORK E ARE CAPABLE OF DOING.
23swordfish ∫F.ds = ∫PAds = ∫PdV
dono me farak kya hai LOL
btw ∫F.ds is more elementary and we shud remember dis
11Swordfish bhaiya, ek advice, dont study too much yaar, seems these days you only
keep on studying and don't go for swimming, isliye you are soooo confused. [3][3]