CHEM 1002 Chapter Notes - Chapter 12.4: Spontaneous Process, Chemical Equation, State Function

• School: Carleton University
• Department: Chemistry
• Course: CHEM 1002
• Professor: Bob Burk

Document Summary

Recall 2nd law of thermodynamics: total entropy always increases during spontaneous process. Diffi(cid:272)ult to (cid:272)al(cid:272)ulate s fo(cid:396) su(cid:396)(cid:396)ou(cid:374)di(cid:374)gs - more convenient to determine direction of spontaneous change using only the system. We want to predict spontaneity while ignoring the surroundings - must look at free energy of the system (gsys) G = h - t s (cid:894)(cid:449)he(cid:396)e s is the fi(cid:374)al s - initial s) - at constant temp. H = (cid:395) for the system since at constant pressure. Remember: heat flow for system is always equal magnitude but opposite in direction. S(cid:894)syste(cid:373)(cid:895) + s(cid:894)su(cid:396)(cid:396)ou(cid:374)di(cid:374)gs(cid:895) = s(cid:894)total(cid:895) the(cid:396)efo(cid:396)e g(cid:894)syste(cid:373)(cid:895)= - t s(cid:894)total(cid:895) at constant p and t) Free energy change is negative whenever total entropy change is positive (hence the negative sign in equation above) - whenever spontaneous. Occur in reactions that happen in human body - 37 c and constant pressure of 1 bar.