Factors Affecting RXN Rates

• Nature of Reactants• Temperature• Concentration• Surface Area•Catalysts/ Inhibitors

Catalyst•Catalysts speed up reactions. (enzymes)

•Inhibitors slow down reactions (preservatives)

Inhibitors

Catalyst / Inhibitors•A substance NOT permanently changed during the reaction.

•Changes energy needed to start reaction

Catalytic converter

•Enzymes

Activation Energy

•Energy needed to start reaction

Energy Diagram

Heat of Reaction: H• Difference between the STORED

Energy of the products and energy of the reactants

H = PEp - PErproducts reactantsChange in heat

Endothermic reaction•Energy is absorbed (in).

•Surroundings get colder

•Eproducts > Ereactants

•▲H is positive

Products have more Energy

Exothermic Reaction•Energy is released (out)

•surrounding get hotter

•Ereactants > Eproducts

•▲H is negative

Products have less Energy

Catalyzed Reactions d9 c23

Hydrogen peroxide Rxt.C34

Catalyst•Works by changing the activation energy required

•The lower the Ea the greater the rate of the reaction.

Inhibitors d9 c38

•Works by changing the activation energy required

•The greater the Ea the lower the rate of the reaction.

Energy Diagram

Inhibitors

Ea