Topic 6-organic chemistry

Question 1

Stereoisomer

Answer 1

-same structural formula
-diff arrangement in space

Question 1

Fractional distillation

Answer 1

-Diff boiling point
-due to diff chain length

Question 2

Free radical substitution

Answer 2

homiletic bond fission, free radicals

Question 3

Alcohol bp

Answer 3

-oh groups form hydrogen bond
-more E needed

Question 4

Cracking

Answer 4

-release short chain alkane and alkene
-demand increased

Question 5

Isomers

Answer 5

-branched chains
-low sa/less point of contact
-weaker London forces so less e needed

Question 6

catalytic converter

Answer 6

2NO+2CO->N2+2CO2

Question 7

cynide reaction

Answer 7

useful as increase carbon chain length

Question 8

heating

Answer 8

-increase reaction rate
-sealed so products don’t escape

Question 9

Rate of hydrolysis

Answer 9

-ethanol as solvent
-silver nitrate
-measure time taken for precipitate
-same temp and volume of halogen

Question 10

How can small UV result in a big product

Answer 10

Radical recycled each time

Question 11

UV and hydrogen

Answer 11

High bond enthalpy for hydrogen so radical not formed as UV not strong enough

Question 12

Incineration

Answer 12

HCl produced
Toxic

Question 13

Use of ethanol

Answer 13

It increases solubility of halogenoalkane/ dissolves haloalkane and water

Question 14

How are halides present in halogenoalkanes

Answer 14

Hydrolysis of halogenoalkane results in heterolytic bond fission

Question 15

Distillation

Answer 15

Not efficient as aldehydes are made due to having lower bp
Aldehydes condense back to further oxidise into carboxylic acid

Question 16

Distillation-improvements

Answer 16

-Anti bumping granules to prevent formation of large bubbles + violent boiling by even distribution of heat
-Thermometer should be at the opposite entrance of condenser
-collect over the right bp range (±1 of bp)
-add more ice mixture to cool as sulphuric acid is very EXOTHERMIC
-conical flask should be open
-water in from the bottom
-reflux-prevent loss of volatile substances
-condenser should be OPEN (no stopper) but between condenser and flask should be closed

Question 17

Burning with smoky flame

Answer 17

-Incomplete combustion
-less exothermic

Question 18

Differences in energy change

Answer 18

delta H is a value with gaseous atoms, but real practicals might not be gaseous

Question 19

Brown vapour in distillation and reflux

Answer 19

Bromine as Br oxidised by conc sulphuric acid

Question 20

Fractional distillation

Answer 20

-Alkanes have diff bp
-due to diff carbon chain length

Question 21

Side reaction in catalytic converter

Answer 21

-Might react with O2
-No might react with Co2

Question 22

Homologous series

Answer 22

-Same functional group
-same general formular
-differ by Ch2

Question 23

Bp of alcohol

Answer 23

-OH groups form hydrogen bonds
-More E needed

Question 24

Reasons for cracking

Answer 24

-Short alkene and alkane
-useful for starting materials (ex-polymers)
-higher in demand

Question 25

Branched chains

Answer 25

-lower SA
-weaker London forces

Question 26

Catalytic converting process

Answer 26

-absorbtion of gasses into catalytic surface
-weakening of bonds on catalytic surface
-deabsorbtion of products made

Question 27

Nucleophillic substitution

Answer 27

End product reacts with a halo radical (ex-chloroethane reacts with cl radical to form dichloroethene and HCl)

Question 28

Uses of polymers

Answer 28

-recycle
-incineration to release E
-feedstock for cracking

Question 29

incineration of poly(chloroethene)

Answer 29

-HCl produced
-corrosive

Question 30

elimination

Answer 30

-ethanolic
-reflux