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Reaction Rate Catalyst Concentration Surface Area Temperature Enzyme Catalytic converter
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1. Energy is involved in every chemical reaction.
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2. Chemical reactions take place at different rates (speeds).
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‘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.
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Rate of reaction A measure of how quickly or slowly reactants turn into products. Quickly = High reaction rate Slowly = Low reaction rate
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Rusting is a ‘slow’ reaction, you hardly see any change looking at it! The weathering of rocks is a very slow reaction.
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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’!
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Rates of reaction are affected by four things: a) Temperature b) Concentration c) Surface area d) Catalysts
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A measure of the average heat energy in a location. Higher temperature = Higher reaction rate Lower temperature = Lower reaction rate
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WHY???? Higher temperature = Faster molecules Lower temperature = Slower molecules
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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).
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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.
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Higher Concentration = Higher reaction rate Lower Concentration = Lower reaction rate
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Higher Concentration = More collisions Lower Concentration = Less collisions
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Assignment: Big book p. 274 - 277
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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
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More Surface Area = More collisions Less Surface Area = Less collisions
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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.
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A catalyst decreases the amount of energy that is required to break the bonds between the reactants so that products can form.
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Enzyme: a biological catalyst It is a special catalyst found in living things
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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!
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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)
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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.
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Assignment: Workbook: p. 115-119
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