1. How Chemical Reactions Occur

2.  molecules must collide in order to react  - a reaction proceeds faster if the concentrations for the reacting molecules are increased  - reactions go faster at higher temperatures

3.  A minimum energy called activation energy (Ea) is needed for a reaction to occur  If a given collision possesses an energy greater than Ea, that collision can result in a reaction.  If a collision has energy less than Ea, the molecules will bounce apart unchanged  At higher temperatures the average collision is more energetic

5.  A catalyst can speed up a reaction without being consumed in the overall reaction  Enzymes are catalysts in our bodies that help speed up complicated reactions that would be too slow to sustain life at normal body temp.  A catalyst works because it provides a new pathway for the reaction- a pathway that has a lower activation energy than the original pathway (more collisions will have enough energy to allow a reaction)

6.  Homogeneous reaction- involves reactants and products in one phase of matter  Heterogeneous reaction- involves reactants and products in two phases of matter  -The speed of a reaction depends on the surface area available  -surface area effects the explosive combustion of grain dust

7.  Chemists define equilibrium as the exact balancing of two processes, one of which is the opposite of the other. ( page 601)  The equilibrium state occurs when the rate of evaporation exactly equals the rate of condensation  There are many chemical reactions that “stop” far short of completion when they are allowed to take place in a closed container.

8.  Chemical equilibrium is a dynamic state where the concentrations of all reactants and products remain constant, as long as the conditions are not changed.  Chemical reactions that are reversible, they can occur in either direction, are indicated by double arrows. Pg 602

9.  Equilibrium is not static but is a highly dynamic situation- it may appear everything has stopped but on the molecular level there is frantic activity