Hi, Igor. Nice to hear from you again. Please do not be offended, but I find
your way of thinking too formal - you are usually right but about
insignificant matters which I see as obvious and do not pay them much
attention. For instance, you wrote:>>>>>>>>>>>>>
Dear Pencho: How can you expect people to discuss with you when all your
premises are wrong? Your formula 1 is neither the first law of
thermodynamics, nor is it ' the most basic definition of chemical work'.
What happened to all other types of work, such as electrical work, work by
gravity, magnetic work etc.? How is it apparent from /1/ that delta H is
the heat absorbed AT CONSTANT PRESSURE? Likewise, your formula /3/ is -
assuming that you remember to put activities for (A) and (B) - an
expression for the MAXIMUM (i.e.REVERSIBLE!) CHEMICAL WORK OBTAINABLE AT
CONSTANT TERMPERATURE AND PRESSURE. Note the word 'reversible'. This is all
texbook stuff | <<<<<<<<<<<<<
Please believe me that there is nothing in your text above that I do not
know. Of course formula 1 is not the first law, but it is derived from the
first law in the following way:
delta H = delta U + P(delta V) = Qabs - Wu - P(delta V) + P(delta V) /1/
There are people for which /1/ is obvious - please become one of them.
Wu is USEFUL work - CHEMICAL is just synonymous. Delta H is not always the
heat absorbed at constant pressure - only when NO USEFUL WORK IS DONE.
I would not forget to put activities in /3/, but in this case this is
immaterial - it is even better to assume that all solutions are ideal and
activities and concentrations coincide. Also, I do know that the work
represented by /3/ is reversible.
Igor, it would be nice for us to put the physical picture before formal
definitions (of course, without ignoring them). Believe me, this creates
problems, but on the other hand is the only way of developing science.
Best regards,
Pentcho
