4.2 Alcohols, haloalkanes and analysis

Question 1

What is the definition of a primary alcohol

Answer 1

Where the functional group is attached to a carbon atom with o more than one alkyl group q

Question 2

What is the definition of a secondary alcohol

Answer 2

Where the functional group is attached to a carbon with 2 alkyl groups

Question 3

What is the definition of a tertiary alcohol

Answer 3

Where the functional group is attached to a carbon with 3 alkyl groups

Question 4

How do the boiling points of alcohols and their corresponding alkanes differ

Answer 4

Hydrogen bonds between the alcohol molecules require more energy to overcome

Question 5

Describe the volatility of alcohols

Answer 5

Alcohols aren’t as volatile as alkenes as they have higher boiling points and volatility decreases as boiling point increases

Question 6

Describe the solubility of alcohols as you go down the homologous series

Answer 6

Alcohol group is polar so methanol, ethanol and propanol are soluble in water

A carbon chain increases the solubility decreases because the aliphatic chain cannot form hydrogen bonds at it makes up most of the molecule

Question 7

What is the product when you oxidise a primary alcohol

Answer 7

1° alcohol (distillation) —> Aldehyde
1° alcohol (reflux) —> carboxylic acid

Question 8

What is the product when you oxidise a secondary alcohol

Answer 8

2° alcohol (reflux) —> ketone

Question 9

What is the product when you oxides a 3° alcohol

Answer 9

Nothing

Question 10

Give examples of oxidising agents

Answer 10

acidified potassium dichromate - orange to dark green
Tollens reagent - silver mirror (aldehyde –> carboxylic acid)

Question 11

Describe a dehydration reaction and its conditions

Answer 11

1° or 2° alcohols —> alkene + H2O

170°C and acid catalyst e.g. H2SO4

Question 12

How do you make an ester

Answer 12

alcohol + carboxylic acid —> ester (-oate) + water
50°C and H2SO4 catalyst

Question 13

How do you draw an ester from its name

Answer 13

Identify parent acid and alcohol

Draw displayed acid first then alcohol (opposite to name )

Take OH from acid and H from alcohol

                                O
                                 II Draw new structure R-C-O

Question 14

What are the two ways to make ethanol

Answer 14

Fermentation
Hydration

Question 15

Describe how we make ethanol via fermentation

Answer 15

Conditions :
35°C 1atm Zymase catalyst (yeast)

glucose —> ethanol + carbon dioxide

Question 16

Describe how we make ethanol via hydration

Answer 16

Conditions
300°C 70atm concentrated phosphoric acid catalyst

alkene + water (steam) —> ethanol

Question 17

what type of process is fermentation

Answer 17

batch

Question 18

what type of process is ethene reaction with steam

Answer 18

continuous

Question 19

What is the reaction rate and purity of ethanol in fermentation

Answer 19

slow
impure

Question 20

What is the reaction rate and purity of ethanol during the ethene reaction with steam

Answer 20

fast
pure

Question 21

what is the definition of a primary haloalkane

Answer 21

the halogen is on the end of the alkyl chain

Question 22

what is the definition of a nucleophile

Answer 22

an electron pair donor

Question 23

what affects the reactivity of haloalkanes

Answer 23

the electronegativity of the halogen can make the molecule more polar

the higher the mean bond enthalpy the less likely the halide will react in a nucleophilic substitution reaction

Question 24

what is the definition of nucleophilic substitution

Answer 24

a reaction where an atom or a group of atoms is exchanged for a nucleophile

Question 25

what kind of fission does water undergo during hydrolysis of haloalkanes

Answer 25

heterolytic fission to produce the nucleophile OH-

Question 26

how do we measure hydrolysis

Answer 26

add the haloalkane and ethanol AgNO3 and water to a test tube and heat in a water bath. Start the timer and note down when a precipitate is formed AgCl- white AgBr- cream AgI - yellow

Question 27

how do we perform hydrolysis using aqueous alkali

Answer 27

e.g. NaOH and heat it will dissociate into OH- and Na+ this is also a nucleophilic substitution reaction

Question 28

what happens to the bonds in cfcs in the atmosphere

Answer 28

the C-Cl bond in C2F2Cl2 undergoes homolytic fission due to the UV radiation C2F2Cl2 —> C2F2Cl• + Cl•

Question 29

why is the ozone layer beneficial to us

Answer 29

it absorbs all of the UV - C radiation and most of the UV-B radiation protecting us from genetic damage and skin cancer

Question 30

why are CFCs bas for the atmosphere

Answer 30

the chlorine radicals catalyse the breakdown of ozone to diatomic oxygen molecules and 1 CFC molecule can destroy 100,000 ozone molecules

Question 31

What is the equation that shows the breakdown of ozone molecules

Answer 31

Cl•+ O3–> O2+ClO• ClO•+O3–>Cl•+2O2

Question 32

How can other radicals affect the ozone

Answer 32

nitrogen oxides (made from the high temperatures in exhaust engines and lighting) can also catalyse the breakdown of ozone to diatomic oxygen

Question 33

Gove the equation that depicts the breakdown of ozone caused by other radicals

Answer 33

NO•+O3–> NO2•+O2 NO2•+O—> O2+NO•

Question 34

give examples of drying agents

Answer 34

magnesium sulfate MgSO4 calcium chloride CaCl2

Question 35

What is the test for alkenes

Answer 35

bromine water orange to colourless

Question 36

What is the test for a haloalkane

Answer 36

add silver nitrate, water and ethanol and a precipitate will form

Question 37

how do you test for a carbonyl

Answer 37

ketones have no changes with all of the tests below but aldehydes do acidified potassium dichromate orange to dark green tollens reagent silver mirror fehlings solution dark red precipitate

Question 38

How do you test for a carboxylic acid

Answer 38

add universal indicator bc its slightly acidic add a reactive metal and there will be effervescence

Question 39

How do you test for and alcohol

Answer 39

Warm with a carboxylic acid and some H2SO4 and there will be a sweet smelling ester produced

Question 40

give two examples of organic compounds with more that one functional group

Answer 40

aspirin — has a carboxylic acid and aromatic ring niacin— has a carboxylic acid and pyridine group