 Reaction Rate  Catalyst  Concentration  Surface Area  Temperature  Enzyme  Catalytic converter

1. Energy is involved in every chemical reaction.

2. Chemical reactions take place at different rates (speeds).

‘Rate of reaction’ means 'the speed of the reaction'. If a reaction is SLOW, that means the molecules combine at a slower speed than a fast reaction. Some reactions take hundreds, maybe even thousands of years while others can happen in less than one second.

Rate of reaction A measure of how quickly or slowly reactants turn into products. Quickly = High reaction rate Slowly = Low reaction rate

Rusting is a ‘slow’ reaction, you hardly see any change looking at it! The weathering of rocks is a very slow reaction.

An example of a fast reaction would be mixing sodium and water to form sodium hydroxide. Explosions and burning/combustion reactions would be described as ‘very fast’!

Rates of reaction are affected by four things: a) Temperature b) Concentration c) Surface area d) Catalysts

A measure of the average heat energy in a location. Higher temperature = Higher reaction rate Lower temperature = Lower reaction rate

WHY???? Higher temperature = Faster molecules Lower temperature = Slower molecules

Sometimes we want slower reactions (we use a fridge to keep food from going bad). Sometimes we want faster reactions (we cook food to speed up the production of new molecules).

Concentration refers to how many particles of a substance exist in a certain amount of liquid (or gas). Concentration is how much solute is dissolved in solution. Concentration = [ ] Changing the concentration of O 2 changes the intensity of flames.

Higher Concentration = Higher reaction rate Lower Concentration = Lower reaction rate

Higher Concentration = More collisions Lower Concentration = Less collisions

Assignment: Big book p

The amount of surface area in contact between the substances during the reaction. More Surface Area = Higher reaction rate Less Surface Area = Lower reaction rate

More Surface Area = More collisions Less Surface Area = Less collisions

A substance that increases the rate of a reaction, but is not used up in the reaction. Adding a catalyst lowers the energy required to start the reaction.

A catalyst decreases the amount of energy that is required to break the bonds between the reactants so that products can form.

Enzyme: a biological catalyst It is a special catalyst found in living things

EXAMPLE: Catalytic converters Found in CARS. Catalytic converters use metals like platinum, palladium and rhodium to convert poisonous compounds in vehicle exhausts into less harmful things. THIS = LESS POLLUTION!

1.Add a catalyst to speed up the reaction 2.Increase the temperature 3.Increase the surface area (break solid into smaller pieces) 4.Increase the concentration of the solution (put more solute in the water)

1.Decrease the temperature where the reaction occurs. 2.Decrease the concentration of reactants. 3.Decrease the amount of surface area that reacts. 4.Remove a catalyst or add an inhibitor.

Assignment: Workbook: p