Chapter 19 Reaction Rates And Equilibrium
Rates Measures the speed of change over an interval of time
Collision Theory Atoms, ions, and molecules can react to form products when they collide with enough kinetic energy.
Activation Energy The minimum amount of energy that particles must have to react.
Transition State The point at the peak of the activation energy where compounds change back to reactants or form new products.
4 Factors affecting Reaction Rates 1.Temperature: Increase in temperature = increase in KE, w/more KE one has more and harder collisions causing more product to form
2. Concentration More molecules means greater chance of collision resulting in the formation of new products.
3. Particle Size (increased surface area) The more surface area you have the greater the chance of collision.
4. Catalyst A substance that speeds up a reaction without being used up in that reaction. Usually written above the yields sign in an equation.
Inhibitors Works against the catalyst.
Reversible Reactions The reaction occurs in both directions at the same time.
2 SO 2 + O 2 2 SO 3
Chemical Equilibrium A state at which the forward and reverse reaction occur at the same rate.
**DOES NOT MEAN** Same amount of product and reactant formed.
LeChatlier’s Principle If stress is applied to a system in dynamic equilibrium, the system changes to relieve the stress.
Concentration Increasing the concentration will always change the equilibrium away from the increased concentration.
H 2 CO 3 CO 2 + H 2 O
Temperature Equilibrium shifts in the direction that absorbs the heat
2 SO 2 + O 2 2 SO 3 + Heat
Pressure (in gasses) Only affects equilibrium if there is an unequal # of moles. Equilibrium moves to the side w/less moles.
K (eq) Equilibrium Constant The lower case letters = # of moles of that compound aA + bB cC + dD
K (eq) = [C] c x [D] d [A] a x [B] b
K (eq) Equilibrium Constant It shows whether products or reactants are favored in the reaction. K (eq) > 1 Products are favored K (eq) < 1 Reactants are favored