Chapter 2-DF5

Question 1

What is an isomer?

Answer 1

Two molecules that have the same molecular
formula but differ in the way their atoms are
arranged

Question 2

What is structural isomerism?

Answer 2

Two molecules with the same molecular
formula but the atoms are bonded together in
a different order. They have different
structural formulae

Question 3

What is chain isomerism?

Answer 3

A type of structural isomerism that has the chain arrangement changed

Question 4

What is position isomer?

Answer 4

A type of structural isomerism where the position of a functional group changes

Question 5

What is functional group isomerism?

Answer 5

A form of structural isomerism where they have the same molecular formula but different functional groups to belong to different homologous series.

Question 6

What is the homologous series?

Answer 6

Hydrocarbons with similar chemical properties who share the same general formula

Question 7

Why is there a shortage of shorter chain fractions?

Answer 7

The demand for lower boiling
point (shorter chain) fractions is
greater than the proportion
found in crude oil
Crude oil contains more higher
boiling point (longer chain)
fractions, which are in lower
demand and are less
economically valuable

Question 8

What is cracking?

Answer 8

A process that splits long chain alkanes into shorter chain alkanes, alkenes and hydrogen.

Question 9

Why is catalytic cracking used?

Answer 9

Using a catalyst allows you to lower the temperatures and pressures needed for the reaction

Question 10

What are zeolites?

Answer 10

minerals that contain mainly aluminium and silicon compounds and are used as catalysts

Question 11

What is a catalyst?

Answer 11

A catalyst is a substance that speeds up the
rate of reaction but can be recovered
chemically unchanged at the end

Question 12

E=What are the two types of catalyst?

Answer 12

Heterogeneous, Homogeneous

Question 13

What is a homogeneous catalyst?

Answer 13

They are catalysts in the same phase as the reactants

Question 14

What are homogeneous catalysts?

Answer 14

They are catalysts in the different phases as the reactants

Question 15

What are the advantages of catalysts?

Answer 15

Lower energy demands-therefore less CO2 produced-therefore less environmental impact-and lower production costs

Question 16

In heterogeneous catalysts what happens on the catalyst surface?

Answer 16

The reactants are adsorbed onto the active site

Question 17

What is catalyst poisoning?

Answer 17

When a catalyst can no longer function fully

Question 18

What happens in heterogeneous catalyst poisoning?

Answer 18

The poison molecules are adsorbed more strongly to the catalyst surface than the reactants

Question 19

Why can lead petrol not be used in cars fitted with a catalytic converter?

Answer 19

The lead is strongly adsorbed to the surface of the catalyst

Question 20

Why do we use expensive metals such as platinum and rhodium instead of cheap ones?

Answer 20

The cheaper metals are vulnerable to poisoning by trace amounts of sulphur dioxide in the exhaust

Question 21

How can we prevent catalyst poisoning in the harbour process?

Answer 21

It can be prevented by ensuring the feedstock chemicals are treated to remove any sulphur compounds

Question 22

Can some catalyst poisoning be reversed?

Answer 22

Yes, In some cases the catalyst can be cleaned or the surface regenerated