Michel Jullian wrote: > > > This makes me think of a nice exercise I wrote a few weeks ago to convince > someone else of path-independence of produced (or absorbed) energy in a net > reaction. > Here it is it's quite relevant to what is discussed here, the > lucky few here who have my spreadsheet (approved by Michael MacKubre, mind > you) can do it without any table lookup nor calculations: > I met Mike Mackubre at a meeting here in the fall of 2000. He struck me as... I reached for the last jelly roll when we were on coffee break. :-)
Fred > ---------- > 1/ In the water evaporation reaction H2O(l)->H2O(g), how much energy > produced (or absorbed if negative) per g of water? > > 2/ Then try the same net reaction but with an intermediate step in > the path: > > 2a/ Dissociate the liquid water: H2O(l)->H2(g) + 0.5 O2(g) > (by electrolysis or whatever, it's irrelevant) > How many J per g of H2O(l)? > > 2b/ Now recombine the gases to get vapor: H2(g) + 0.5 O2(g) -> H2O(g) > (explosively, catalytically, it's irrelevant) > How many J per g of H2O(g)? > > 3/ How many J net for 2a/ + 2b/ per g of water, how does it compare > with the result for 1/? > ---------- > > Cheers, > Michel >
