Question

how do you find the q and w

In each of the following give the sign of q and w. CH,(9) + 202(g) + CO2(g) + 2H2O(g) C&H 20 (aq) + 602(9) — 6CO2(g) + 6H20(9)| CoH120o (aq) + 60,(9) ► 600,(9) + 6H,00) H20() → H2O(g)

Answer 1

Sign Comvention Joe Heat Abesarbed by the ystem 18 Pasitive -Heat Rejected asc given out by the sustem -i3 negahive Fosr, the lollowing Sreachion, /is negative as the 9reactions ate undergoing Combughion, 3o the Sreactions are exothermic 7CH4C9) 4202 (g)Co2g)+2H20 le) GHIZO6 Caq)+ 602 Cg)-6CO2 g) +6H209) Cs Hz as Ga) t 602 g)-76C02) 6H20(9) For this Dreaction there is only phase change. ThereJere, tspesitive- H20C) H209) Sign Convention ddec W- Accoording to ist law theamodynam ics, Q=V+W Uis internal enezgy, which ts a junction ol temp Since temperahure is decneasing in the dorst three Hence Uis aegative decteasing Ca 8ign Conventfon das W depends on the magnitude lu by the System, Wis Pasitive Ereachions, Nceckis done Wis negative IWasck is done by Us Car the dost three Steachien Qi8 negatve, thenefre W -a,-V <0, Hente N i&0 daJirest fase doweth S9reachon UO, because phage Change lakes plae thnee Sreachan at Carst demp, Hence a- W, Sinceis tve, Wis pasihve.