10.2 Catalysts

Question 1

What is a catalyst

Answer 1

A substance that changes the rate of a chemical reaction without undergoing any permanent change itself
Catalyst is not used up in chemical reaction
Catalyst may react with a reactant to form an intermediate or may provide a surface on which the reaction can take place
At the end of the reaction, the catalyst is regenerated

Question 2

A catalyst ______ the rate of a chemical reaction by providing an ______ reaction ______ of lower ______ energy.

Answer 2

Increases
Alternative
Pathway
Activation

Question 3

A homogeneous catalyst has the ______ physical state as the reactants. The catalyst reacts with the reactants to form an ______. The ______ then breaks down to give the product and ______ the catalyst.

Answer 3

Same
Intermediate
Intermediate
Regenerates

Question 4

Examples of reactions of gases and liquids that use homogenous catalysis

Answer 4

Making esters with sulfuric acid as a catalyst
Ozone depletion (Cl• radicals as catalyst)

2O3(g) 3O2(g)
The reactant and catalyst are both gases

Question 5

A heterogeneous catalyst has a ______ physical state from the reactants. Heterogeneous catalysts are usually ______ in contact with ______ reactants or reactants in ______. Reactant molecules are ______ onto the surface of the catalyst where the reaction takes place. After the reaction, the product molecules leave the surface of the catalyst by ______.

Answer 5

Different
Solids
Gaseous
Solution
Absorbed
Desorption

Question 6

What do catalytic converters contain

Answer 6

A catalyst made of platinum, rhodium and palladium supported on a honeycomb mesh that provides a large surface area on which the reactions can take place.

Question 7

How do catalytic converters work

Answer 7

Contain a catalyst made of platinum, rhodium and palladium on a honeycomb mesh to provide a large SA on which reactions can take place.
Hot exhaust gases are passed over this heterogeneous catalyst, and harmful gases are converted into less harmful products.

Question 8

What does combustion in a petrol engine form

Answer 8

The toxic gases carbon monoxide and nitrogen monoxide.

Question 9

What does a catalytic converter convert carbon monoxide to

Answer 9

Oxidised to form carbon dioxide

Question 10

What does a catalytic converter convert nitrogen monoxide

Answer 10

Reduced to nitrogen gas

Question 11

What are any unburnt hydrocarbons oxidised to in a catalytic converter

Answer 11

Oxidised to water and carbon dioxide

Question 12

It is estimated that 90% of all chemical materials are produced using…

Answer 12

…a catalyst

Question 13

Catalysts increase the rate of many industrial chemical reactions by…

Answer 13

…lowering the activation energy. This then reduces the temperature needed for the process and the energy requirements

Question 14

If a chemical process requires less energy, then less…

Answer 14

…energy or fossil fuel is used

Question 15

What is the modern focus on sustainability

Answer 15

Requires industry to operate processes with high atom economies and fewer pollutants
Using less fossil fuel will cut emissions of carbon dioxide

Question 16

When is a chemical reaction said to have undergone autocatalysis

Answer 16

If a reaction product acts as a catalyst for that reaction

Typically the reaction starts slowly and then speeds up as the products are formed

Question 17

Example of autocatalysis

Answer 17

2MnO4- + 16H+ + 5C2O42- –> 2Mn2+ + 8H2O + 10CO2