Topic 5 + 6 - Intro to organics + Halogenoalkanes

Question 1

What is a homologous series?

Answer 1

A series of molecules that show a gradual trend in physical properties, can be represented by a general formula and have the same functional group. Each successive member of the series differs by a CH2 group

Question 2

Alkanes are saturated or unsaturated?

Answer 2

saturated

Question 3

What is an isomer?

What are the 3 types?

Answer 3

Molecules with the same molecular formula but different structural formulae.

3 types:
Chain
Position
Functional

Question 4

What is fractional distillation?

Answer 4

The continued evaporation and condensation of a reaction causing it separate due to differences in boiling points.

Question 5

What is petroleum?

Answer 5

A complex mixture containing mainly alkane hydrocarbons that can be separated using fractional distillation.

Question 6

Why do people using cracking?

Answer 6

To break up the less valuable (less in demand), longer chain hydrocarbons that are less flammable, into shorter chain alkanes and alkenes

Question 7

What are the two types of cracking called?

Answer 7

Thermal and Catalytic

Question 8

Describe thermal cracking and its benefits

Answer 8

High temp (up to 1000 degrees)

High pressure (up to 70 atm)

Produces lots of alkenes which can be used to make valuable polymers eg. poly(ethene)

Question 9

Describe catalytic cracking and its benefits

Answer 9

Uses a zeolite catalyst at a slight pressure and high temp (450)

Mostly produces aromatic hydrocarbons and motor fuels

Using a catalyst cuts costs as it can be done at a lower pressure and temperature and it also speeds up the reaction which saves time.

Question 10

Alkanes are useful for?

Answer 10

Fuels

Question 11

Complete combustion of alkanes produces?

Answer 11

CO2 and H2O

Question 12

What is produced/ can be produced in incomplete combustion?

Answer 12

Carbon Monoxide

Carbon dioxide

Carbon

Question 13

How are oxides of nitrogen formed in the internal combustion engine?

Why is it bad?

Answer 13

High temperature and pressure inside car engines cause nitrogen and oxygen atoms in the air to react together.

Acid rain

Question 14

How is the pollutant carbon formed in the internal combustion engine?

Why is it bad?

Answer 14

Incomplete combustion of hydrocarbons

Breathing problems and can also build up causing engine problems

Question 15

How is the pollutant carbon monoxide formed in the internal combustion engine?

Why is it bad?

Answer 15

Incomplete combustion of hydrocarbons

Toxic to humans - limits RBCs capacity to carry oxgen

Question 16

What is the issue with unburn hydrocarbons as a result of internal combustion engines?

Answer 16

React in the presence of sunlight to form ground level ozone (O3).

This irritates peoples eyes and is very bad for the respiratory system

Question 17

How can (which) emissions be reduced using catalytic converters?

Answer 17

They reduce the output of carbon monoxide, nitrogen oxide and unburnt hydrocarbons.

Honeycomb shape (large surface area) made of ceramic material coated in platinum and rhodium (catalysts).

As the gases pass over this they react forming less harmful products. eg. co2 and nitrogen

Question 18

How can we limit sulfur dioxide reaching the atmosphere in flue gases?

Answer 18

Calcium carbonate or calcium oxide is mixed with water to form an alkaline slurry.

The flue gases mix with the slurry and the acidic sulfur dioxide reacts with calcium compounds to form harmless salts.

Question 19

Why is the ozone layer important?

Answer 19

Absorbs UV radiation which could be potentially harmful.

Question 20

What are CFCs?

Answer 20

Chlorofluoroalkanes where all the hydrogens have been replaced by chlorine and fluorine atoms.

Question 21

Why are CFCs bad?

Answer 21

Create holes in the ozone layer

Question 22

How do CFCs create holes in the ozone layer?

Answer 22

Chlorine free radicals are forming in the ozone layer when C-Cl bonds are broken by UV radiation.

These free radicals are catalysts.

They attack the ozone in the atmosphere and regenerate more Cl free radicals.

It breaks down ozone into oxygen

Question 23

What are the 2 equations and overall equation that show the decomposition of the ozone layer?

Answer 23

Question 24

What is a nucleophile?

Answer 24

An electron pair doner?

Question 25

Conditions for nucleophilic substitution of OH- CN-

Answer 25

Reflux reaction.

Alkane dissolved in ethanol
Aqueous sodium cyanide/hydroxide

Question 26

Nucleophillic substitution using ammonia conditions?

Answer 26

Sealed container under pressure
Dissolve bromoethane in ethanol
Add concentrated NH3

Question 27

Why do iodoalkanes react faster than fluoroalkanes?

Answer 27

As the C-I bond is shorter than C-F and therefore takes less energy to break.

Bond needs to break for the reaction to occur

Question 28

What is a free radical?

Answer 28

A particle with an unpaired electron

Question 29

What are the conditions for elimination reactions?

Answer 29

Alkaline and under reflux - dissolved in ethanol

Question 30

Which solutions favour elimination and which conditions favour substitution?

Answer 30

Ethanolic solutions favour elimination

Aqueous solutions favour substitution