Chapter 6 – 4 Chemical Reactions Rates of Change

Rate of Change Chemical reactions occur at different rates or speeds. Explosion of nitroglycerine Fast Burning of carbon in charcoal Slow

Reaction Rate Most reactions go faster at higher temperatures Faster moving particles collide more often = more chance for a reaction

Bread in freezer vs Bread on counter

Rate of Reaction A large surface area speeds up reactions

Rate of Reaction Concentrated solutions react faster A drop of bleach vs a bottle of bleach

Rate of Reaction Reactions are faster at higher pressure Less space = more collisions

Rate of Reaction Massive molecules react slower The bigger it is the slower it moves = less collisions

Catalysts Catalyst – substance that changes the rate of a reaction Speed up or slow down Inhibitor – slows down

Enzymes Enzyme – type of protein that speeds up metabolic reactions in plants and animals Substrate – a molecule upon which an enzyme acts

Chemical Equilibrium Chemical Equilibrium – a state of balance in which the rate of a forward reaction equals the rate of the reverse reaction A balanced state Carbonated drinks

Chemical Equilibrium Molecules of CO2 are constantly moving in and out of the solution Football players moving off and on field but always 11 on the field

Le Chatelier’s Principle If a change is made to a system in chemical equilibrium, the equilibrium shifts to oppose the change until a new equilibrium is reached. Predicts changes in equilibrium.

Le Chatelier’s Principle Effects of change: Temperature – increase favors reaction Pressure – increase favors reaction Concentration – increase favors reaction

P.212 #1-3, 6 P. 197 #1,4,6,7 P.189 #1-4