Unit overview

This unit provides students with opportunities to understand the enthalpy cchanges that accompany chemical reactions. The unit should be treated both qualitatively and quantatatively. The use of analogies, models, and kinetic molecular theory may help students to appreciate how energy changes relate to what changes are taking place at the atomic leve.

Students need to be able to interpret information from charts, tables, and graphs. They should compare the determination of enthalpy change by use fo bond energy datya, tables of heats of formation, and the application of Hess's Law, and discuss any discrepancies observed.

The consideration fo enthalpy effects in chemical reactions should be clearly linked to the combustion of carbon based fuels to rpovide energy for our society. The stability of the CO2 and H20 molecules, which makes the burning of hydrocarbon molecules so exothermix and therefore so attractive, and the contribution of CO2 to global warming should be discussed.

Discussion fo the entropy, free energy and the mathematical determination of the spontanity of reaction is optional.