CHEN 3101 Lecture Notes - Lecture 1: Heat Capacity, Absolute Difference, Paga

• School: UMN
• Department: Chemical Engineering
• Course: CHEN 3101
• Professor: David Morse

Document Summary

When rxn conditions change (e. g. t or p) are changed, rxn shifts in direction that opposes the change. When t is increased, reaction equilibrium shifts in the direction that consumes heat (endothermic) Original statement: if rxnho > 0 (endothermic) ka increases as t increases. If rxnho < 0 (exothermic) ka decreases as t increases. Chen thermo page 1 exothermic endothermic hot cold figure 13. 1-2 in sandler has different rxns and their plot (p. 717) really look like straight lines over large ka range. Bond energies (values from textbook by pauling, general chemistry) these are all binding energies --> energies go down by this amount when forming those bonds. Chen thermo page 2 don"t usually change total # bonds in system, in such systems, have differences of < 10 2 - 103 kj/mol. Ex: h2 + ch2=ch2 --> ch3ch3 ethane ethylene. 1 h-h --> 436 total = 123 kj. mol. S >= 0 (favorable) if > 0.