1. Office Hours 367J Noyes Lab decoste@illinois.edu 11am-12pm Mondays and Wednesdays (after lecture) 10-11 am Tuesdays and 1-2 pm Thursdays By appointment; open-door policy 1

2. Lon-Capa 4 th HW assignment due Friday, 10/9, 5 pm. It is open now. 3 rd Quiz due Sunday, 10/11 by 10 pm. It will open Friday, 10/9 at 5 pm. 2

3. 3 Three Big Topics Stoichiometry: information on “what” happens; allows us to determine amounts of reactants and products. Thermodynamics: information on “why” reactions happen; allows us to make predictions about whether a reaction will occur. Kinetics: information on “how” reactions happen (mechanisms); relates to the speed of reactions.

4. 4 “Ball on a Hill”

5. 5 Questions To Consider How can we predict which reactions are spontaneous (and what do we mean by spontaneous)? How can we provide support (mathematical and qualitative) for observations? Ice cream melts Coffee cools Why do systems reach equilibrium? That is, why doesn’t the ball go “all the way down the hill”?

6. 6 Clicker Question The freezing of water is an ________ process. a) exothermic b)endothermic c) I do not know.

7. Temperature: measure of KE avg 7

8. 8 Clicker Question The following chemical reaction is exothermic: A 2 + B 2  2AB. This means: more stable higher average bond energies a) ReactantsReactants b)ReactantsProducts c) ProductsProducts d) ProductsReactants e) I do not know.