Many factors can determine the rate a chemical reaction occurs.Many factors can determine the rate a chemical reaction occurs. TemperatureTemperature ConcentrationConcentration Surface areaSurface area CatalystsCatalysts See pages A bicycle chain slowly rusts 6.2 – Factors Affecting Reaction Rate

Temperature Temperature Temperature is a measure of the average energy of molecules.Temperature is a measure of the average energy of molecules. The more energy molecules have, the higher the temperature.The more energy molecules have, the higher the temperature. Higher temperature = faster reaction rate.Higher temperature = faster reaction rate.

Concentration Concentration Concentration refers to how many molecules of a substance exist in a certain volume (g/L).Concentration refers to how many molecules of a substance exist in a certain volume (g/L). Higher Concentration = faster reaction rateHigher Concentration = faster reaction rate - Since there are more molecules per unit volume in high concentrations, there are more opportunities for molecules to collide & react. - Since there are more molecules per unit volume in high concentrations, there are more opportunities for molecules to collide & react. Changing the concentration of O 2 changes the intensity of flames.

Surface Area Surface area is how much of the material is exposed to the air or other reactants.Surface area is how much of the material is exposed to the air or other reactants. Higher surface area = faster reaction rate.Higher surface area = faster reaction rate. Since there are more atoms and compounds exposed to react, more reactions take place.Since there are more atoms and compounds exposed to react, more reactions take place. Steel wool (on the right) is made up of small strands of steel, and therefore has much more surface area than an equivalent amount of solid steel.

Catalysts A catalyst is a chemical that allows a reaction to occur more quickly without actually participating in the reaction itself.A catalyst is a chemical that allows a reaction to occur more quickly without actually participating in the reaction itself. Catalyst = faster reaction rate (not part of the reactants).Catalyst = faster reaction rate (not part of the reactants). Catalysts lower the amount of energyCatalysts lower the amount of energy needed to break the bonds in the reactants. Eg. Enzymes are biological catalystsEg. Enzymes are biological catalysts Salivary amylase increases the digestion of starches.

Catalytic Converters A catalytic converter is a device installed in all cars to decrease pollution.A catalytic converter is a device installed in all cars to decrease pollution. Catalysts found in the honeycomb-shaped filters in the converter help to change many of the pollutants.Catalysts found in the honeycomb-shaped filters in the converter help to change many of the pollutants. Poisonous CO is changed into CO 2Poisonous CO is changed into CO 2 Hydrocarbons are converted into CO 2 & H 2 OHydrocarbons are converted into CO 2 & H 2 O Nitrogen oxides are changed into N 2 & O 2Nitrogen oxides are changed into N 2 & O 2 2N 2 O 3  2N 2 + 3O 22N 2 O 3  2N 2 + 3O 2 Take the Section 6.2 Quiz