How Do Catalysts Speed Up Reactions? L.O: To understand how catalysts affect the rate of a reaction.

How Do Catalysts Speed Up How Do Catalysts Speed Up Reactions?Reactions?

L.O: To understand how catalysts L.O: To understand how catalysts affect the rate of a reactionaffect the rate of a reaction

Oxygen can be produced by the chemical reaction Oxygen can be produced by the chemical reaction

Hydrogen peroxide Hydrogen peroxide Water + Oxygen Water + Oxygen

How could you make this reaction happen quickly to How could you make this reaction happen quickly to supply low hospitals? Remember it needs to be cheap supply low hospitals? Remember it needs to be cheap on the NHS and safe!!on the NHS and safe!!

Catalysts Catalysts For chemical reactions to occur:For chemical reactions to occur:

• Existing bonds have to begin Existing bonds have to begin breaking so that new ones can be breaking so that new ones can be formed.formed.• The molecules have to collide in The molecules have to collide in such a way that the reacting parts of such a way that the reacting parts of the molecules are brought together.the molecules are brought together.

Catalysts can help with either or Catalysts can help with either or both of these processes.both of these processes.

A catalyst is a substance that speeds up a reaction without getting used up in the process.

Catalysts never produce more product – they just produce the same amount more quickly.

Other catalysts, especially enzymes, absorb molecules in a Other catalysts, especially enzymes, absorb molecules in a way that not only stretches bonds but also brings the way that not only stretches bonds but also brings the reacting parts of reactants right next to each other.reacting parts of reactants right next to each other.

Catalysts Catalysts

H HH H

H HH HHH HHBond stretched

The stretching of the H-H bond lowers the activation energy and helps hydrogen react with the oil

Ni NiNi Ni NiNicatalyst

Catalysts Catalysts

• In the presence of a nickel catalyst vegetable oil and In the presence of a nickel catalyst vegetable oil and hydrogen react to form margarine.hydrogen react to form margarine.

• Nickel adsorbs hydrogen gas onto its surface in such a Nickel adsorbs hydrogen gas onto its surface in such a way that the bond holding the hydrogen molecule way that the bond holding the hydrogen molecule together becomes stretched.together becomes stretched.

• This partial breaking of the bond lowers the activation This partial breaking of the bond lowers the activation energy making hydrogen more reactive.energy making hydrogen more reactive.

Hydrogen Peroxide (HHydrogen Peroxide (H22OO22))

• Is a pale blue liquid slightly more viscous Is a pale blue liquid slightly more viscous than waterthan water

• It is found in disinfectant, bleachesIt is found in disinfectant, bleaches

• In virtually all living organisms there are In virtually all living organisms there are peroxidases peroxidases (enzymes) which decompose (enzymes) which decompose hydrogen peroxide into oxygen and water.hydrogen peroxide into oxygen and water.

• Hydrogen peroxide is very oxidising so can Hydrogen peroxide is very oxidising so can loose its extra oxygen.loose its extra oxygen.

Your task is to find the best catalyst to break down hydrogen Your task is to find the best catalyst to break down hydrogen peroxide and produce oxygen quickly for hospitalsperoxide and produce oxygen quickly for hospitals

• You will be investigating catalysts manganese You will be investigating catalysts manganese dioxide, lead oxide, iron oxide and liver.dioxide, lead oxide, iron oxide and liver.

• They will vary in effectivenessThey will vary in effectiveness• You will need to measure the oxygen production You will need to measure the oxygen production

every 10 secs for up to 2 mins to find out which is every 10 secs for up to 2 mins to find out which is the best catalyst at speeding the rate of reaction.the best catalyst at speeding the rate of reaction.

Design your experiment using the equipment Design your experiment using the equipment provided.provided.

Draw your own results table to record the results.Draw your own results table to record the results.

Catalysts are used in the manufacture or Catalysts are used in the manufacture or application of a huge number of products.application of a huge number of products.

Synthetic materials like polyester are made using a

catalyst.

Plastics are made using catalysts.

Biological soap powder uses

biological catalysts (enzymes)

Enzymes in pineapple help cooked ham to be more tender.

Catalysts Catalysts

Catalytic Converters in cars – converting nitrous

oxide and carbon monoxide to carbon dioxide and nitrogen

Catalytic converters in carsCatalytic converters in cars

Catalytic converters have a high surface area to increase the rate of reaction. They also work best at high temperatures.

A catalytic converter is a device that is fitted to the exhaust pipe of a car to clean up exhaust fumes. The converter uses platinum as a catalyst. It catalyzes the conversion of carbon monoxide and nitrogen oxide into the less polluting carbon dioxide and nitrogen.

Brita Filters use catalystsBrita Filters use catalysts

A Brita filter removes A Brita filter removes unwanted ions like unwanted ions like chlorine, copper and lead.chlorine, copper and lead.

Inside the filter a Inside the filter a chemical reaction occurs chemical reaction occurs quickly on a carbon quickly on a carbon catalyst to remove carboncatalyst to remove carbon

Make a table of the advantages and Make a table of the advantages and disadvantages of using brita filters or catalytic disadvantages of using brita filters or catalytic converters.converters.

Advantages Disadvantages

Catalysts in industryCatalysts in industry

Products can be made more quickly, saving time and money.

Catalysts reduce the need for high temperatures because less energy is required for reactions. This saves fuel and reduces pollution.