Alcohols 15

Question 1

ethanol

Answer 1

promotes a feeling of well-being and depresses the nervous system and affects balance and coordination

alcoholic drinks are absorbed through the walls of the stomach and small intestine into the blood stream.

the average person can eliminate 10cm3 of ethanol per hour

Question 2

antifreeze

Answer 2

ethane-2,3-diol main ingredient

Question 3

shape

Answer 3

C-O-H angle is 105 degrees

Question 4

alcohol classification

Answer 4

primary = attach to only one carbon
secondary = attach to two carbons
tertiary = attach to three carbons

Question 5

physical properties

Answer 5

hydrogen bonding

short hydrocarbon chains are soluble in water because hydrogen bonding predominates

Question 6

uses of ethanol

Answer 6

aftershave
perfume
drugs
detergents
ins
coatngs

Question 7

ethanol - crude oil

Answer 7

hydrated (water added to the double bond) (electrophilic addition)

phosphoric acid catalyst or concentrated sulphuric acid

excess stream
pressure 50 to 100 atmospheres
high temperature

Question 8

ethanol - fermentation

Answer 8

breaking down sugars using yeast

anaerobic respiration
glucose —– ethanol + carbon dioxide

the rate of reaction affected by temperature, slow at low temperature but a high temperature can denature the enzyme

carbon neutral

Question 9

method

Answer 9

-crude oil
cracking and hydration

-sugars
fermentation and distillation

Question 10

the rate of reaction

Answer 10

-crude oil
fast

-sugars
low

Question 11

type of process

Answer 11

-crude oil
continuous

-sugars
batch

Question 12

purity

Answer 12

-crude oil
essentially pure

-sugars
aqueous solution of ethanol is produced

Question 13

renewable source of ethene

Answer 13

vital industrial chemical

starting material fro poly(ethene) and many other chemicals.

Question 14

dehydration

Answer 14

alcohols can be dehydrated with excess hot concentrated sulfuric acid or passing vapours over heated aluminium oxide
phosphoric acid is an alternative dehydrating agent

Question 15

oxidation primary alcohol

Answer 15

aldehyde —– carboxylic acid

using Acidified potassium dichromate(VI)

Question 16

oxidation secondary alcohol

Answer 16

ketone

Question 17

oxide ethanol to ethanal (aldehyde)

Answer 17

• dilute acid and less potassium dichromate than is needed to complete oxidised
• mixture is heated
• receiver cooled in ice to reduce evaporation of the product. ethanal vaporises and distilled off

Question 18

oxidise ethanol to ethanoic acid (and water)

Answer 18

concentrated sulfuric acid and enough potassium dichromate.

• refluxed
• the vapour drips back into the container so everything in oxidised

Question 19

The Tollen’s (silver mirror) test

Answer 19

silver nitate in aqueous ammonia
oxidises aldehydes no effect on ketones
deposit of metallic silver is formed on the inside of the test tube

Question 20

Fehling test

Answer 20

blue copper (11) complex which will oxidise aldehydes but not ketones

blue solution gradually turns to brick red precipitate of copper(1) oxide

on warming the brick red precipitate gradually forms

Question 21

nucleophilic substitution

Answer 21

heat

sodium/ potassium hydroxide

Question 22

hydration

Answer 22

cracking and hydration
from crude oil and steam
fast reaction
continuous process
CH2=CH2 + H20 ------- C2H5OH
(phosphoric acid catalyst)
essentially pure
mechanism needed

Question 23

fermentation

Answer 23

sugar is broken down by yeast and then distillations
made from sugar and yeast
rate of reaction is low at low temperatures but at high temperatures enzymes are inactive
batch process
C6H12O6 ——- 2C2H5OH + 2CO2
has to be kept away from oxygen to prevent oxidation
15% pure
no mechanism needed
(Ethanol produced industrially by fermentation is separated by fractional distillation and can then be used as a biofuel.)

Question 24

combustion (complete oxidation)

Answer 24

lots of oxygen
heat

C2H5OH + 3O2 —— 2CO2 + 3H2O

Question 25

oxidation of secondary alcohols

Answer 25

ketone and water

acidified potassium dichromate

Question 26

oxidation of tertiary alcohols

Answer 26

not easily oxidised

Question 27

reflux

Answer 27

letting a solvent boil and collecting it vapour in some kind of condenser to let it drip back into the reaction vessel

Question 28

distillation

Answer 28

the separation of the constituents of a liquid by boiling it then condensing the vapour that results

Question 29

dehydration

Answer 29

the reaction in which an alkene and water are produced from and alcohol

Question 30

how are alcohols are made

Answer 30

Alcohols are produced industrially by hydration of alkenes in the presence of an acid catalyst.

Question 31

elimination

Answer 31

Alkenes can be formed from alcohols by acid-catalysed elimination reactions