Reaction Rates Reaction Rates Collision Theory 5 Factors Affecting Rates

A. Rates Rate: measure of change over time

reactants  products A. Rates Reaction Rate: rate at which reactants change into products over time. (tell how fast a reaction is going) Example: TNT & rusting reactants  products get consumed get formed

A. Rates more reactants more products reactants products

B. Collision Theory Ineffective Collision Effective Collision

Activation Energy (Eact) B. Collision Theory For reaction to occur: reactants must collide with proper orientation with enough energy needed to react called Activation Energy (Eact)

Reactants energy energy released (in bonds) Product Potential Reaction progress →

? Reactants energy energy released (in bonds) Product Potential Reaction progress →

B. Collision Theory break reactant bonds Eact ΔE

C. 5 Factors Affecting Rates The speed that a reaction takes place can be affected by: Temperature Surface Area Stirring Concentration Catalysts

1) Temperature Temp. Rate Why does milk last l0nger in the fridge? more energy more collisions Direct or inversely proportional

2) Surface Area Surf. Area Rate more collisions

3) Stirring Stirring Rate more collisions

4) Concentration Conc. Rate more collisions

4) Concentration Conc. Rate more collisions

5) Catalysts speed up a reaction without being consumed. lower the activation energy (Ea). Like a party helps people meet each other and helps build friendships

Like a party helps people meet each other and helps build friendships

Why is H2O2 stored in dark plastic bottles? 5) Catalysts Demo: catalyst written above arrow MnO2 2 H2O2  2 H2O + O2 DEMO (Genie in a Bottle): 40 mL 30% H2O2 in 250 mL Florence flask. 1 tsp of MnO2 in tissue on string with cork stopper holding hanging. Why is H2O2 stored in dark plastic bottles?

Quick Quiz! 1) An increase in which one of the following will NOT increase the reaction rate? A) temperature B) concentration of reactants C) total mass of reactants D) surface area of reactants

Quick Quiz. 2) A catalyst speeds up a reaction by A) lowering the activation energy. B) increasing the temperature C) permanently changing in a reaction D) supplying energy to a reaction