4) Organic Chemistry P2

Question 1

Alcohols

Answer 1

Homologous series of compounds
-all contain the functional group -OH bonded to a carbon chain

Question 2

Methanol molecular, structural, displayed formula

Answer 2

CH4O
CH3OH
Draw displayed

Question 3

Ethanol molecular, structural, displayed formula

Answer 3

C2H6O
CH3CH2OH
Draw displayed

Question 4

Propan-1-ol molecular, structural, displayed formula

Answer 4

C3H8O
CH3CH2CH2OH
Draw displayed

Question 5

Butan-1-ol molecular, structural, displayed formula

Answer 5

C4H10O
CH3CH2CH2CH2OH
Draw displayed

Question 6

Naming alcohols

Answer 6

e.g. Butan-1-ol
But - 4 carbon chain
an - saturated
1 - functional group on carbon 1 at lowest possible number from any direction
ol - -OH functional group

Question 7

Ways ethanol can undergo oxidation

Answer 7

-complete combustion
-microbial oxidation
-treatment with an oxidising agent (heating with potassium dichromate(VI) in dilute sulfuric acid to form ethanoic acid)

Question 8

Oxidation of ethanol - combustion

Answer 8

Alcohols undergo combustion to form carbon dioxide and water

Question 9

Oxidation of ethanol - microbial oxidation

Answer 9

Bacteria in the air use oxygen in the air to oxidise the ethanol in the wine:
ethanol + oxygen → ethanoic acid + water

Question 10

Oxidation of ethanol - treatment with an oxidising agent

Answer 10

Alcohols undergo oxidation to produce carboxylic acids when treated with oxidising agents
-ethanol heated with acidified potassium dichromate (VI)
-oxidises to ethanoic acid
-potassium dichromate turns from orange to green

Question 11

Production of ethanol

Answer 11

-hydration of ethene
-fermentation

Question 12

Production of ethanol - Hydration of ethene

Answer 12

Addition reaction where water is added to the ethene without forming any other product
Conditions:
-temp: 300C
-pressure: 60-70 atm
-concentrated phosphoric acid catalyst

Question 13

Production of ethanol - Fermentation

Answer 13

-yeast added to sugar/ starch, left in warm and anaerobic conditions
-enzymes in yeast convert sugar into carbon dioxide and ethanol
-optimum temp: 30C
C6H12O6 –> 2C2H5OH + 2CO2

Question 14

Fermentation vs hydration of ethene - resources, type of process, rate, quality, conditions

Answer 14

F: use renewable resources
H: Non renewable (ethene in crude oil)

F: batch process - inefficient
H: continuous flow process - more efficient

F: Slow, several days for each batch
H: fast

F: impure ethanol, needs further processing
H: much purer ethanol

F: gentle temps, atm
H: high temp, pressure, require high input of energy

Question 15

Carboxylic acids

Answer 15

Homologous series of compounds that contain the -COOH functional group (Carboxyl)

Question 16

Vinegar

Answer 16

Aqueous solution of ethanoic acid (diluted in water)

Question 17

Methanoic acid molecular, structural, displayed formula

Answer 17

CH2O2
HCOOH
Draw displayed

Question 18

Ethanoic acid molecular, structural, displayed formula

Answer 18

C2H4O2
CH3COOH
Draw displayed

Question 19

Propanoic acid molecular, structural, displayed formula

Answer 19

C3H6O2
CH3CH2COOH
Draw displayed

Question 20

Butanoic acid molecular, structural, displayed formula

Answer 20

C4H8O2
CH3CH2CH2COOH
Draw displayed

Question 21

Naming carboxylic acids

Answer 21

e.g. Butanoic acid
But - 4 carbon chain
an - saturated
oic acid - -COOH functional group

Question 22

Acid properties of carboxylic acids

Answer 22

-considered weak acids (pH3-5)
-turn litmus paper red
-universal indicator orange or yellow
-react same as other acids

Question 23

Carboxylic acids + metals

Answer 23

–> salt + hydrogen
e.g. magnesium + ethanoic acid –> magnesium ethanoate + hydrogen

Question 24

Ethanoate ions

Answer 24

Form when the ethanoic acid loses a hydrogen, become negatively charged
CH3COOH –> CH3COO-

Question 25

Carboxylic acids + metal carbonates

Answer 25

--> salt + water + carbon dioxide -fizzing produced -gas produced turn limewater cloudy

Question 26

Esters

Answer 26

Homologous series of compounds that contain the -COO functional group

Question 27

ethyl ethanoate - structural, displayed formula

Answer 27

CH₃COOCH₂CH₃ Draw displayed formula

Question 28

Formation of esters

Answer 28

React an alcohol and carboxylic acid in warm conditions in the presence of a sulfuric acid catalyst ethanol + ethanoic acid --> ethyl ethanoate in presence of acid catalyst

Question 29

Practical: prepare a sample of an ester such as ethyl ethanoate

Answer 29

1. Take mixture of ethanol and ethanoic acid in test tube 2. Add drops of concentrated sulfuric acid 3. Place test tube in beaker of hot water for 15 minutes 4. Empty test tube onto cold sodium carbonate solution 5. Bubbling observed 6. Thin layer of ester floating on the surface

Question 30

Drawing esters

Answer 30

Draw alcohol and carboxylic acid side by side -OH removed from carboxylic acid -H removed from alcohol O from alcohol bonds to C from acid to make ester bond -always draw acid section and then alcohol section -draw methanol + propanoic acid -draw propanol + ethanoic acid

Question 31

Naming esters

Answer 31

e.g. Butyl Propanoate Butyl - 4 carbon alcohol Prop - 3 carbon carboxylic acid an - saturated oate - -COO functional group

Question 32

Splitting up esters

Answer 32

-condensation reaction to make esters can be reversed to return back to alcohol and carboxylic acid -hydrolysis reaction - add water

Question 33

Uses of esters

Answer 33

-small esters commonly used in solvents -sweet, fruity smell -in perfumes, food flavourings -volatile - evaporate easily

Question 34

Condensation polymerisation

Answer 34

Alcohols and carboxylic acids combine to form ester bonds (-COO) -two different monomers join in an alternate pattern -each ester bond formed causes a small molecule of water to be removed

Question 35

Monomers of condensation polymerisation

Answer 35

Diols contain two -OH functional groups Dicarboxylic acids contain two -COOH functional groups

Question 36

Process of condensation polymerisation

Answer 36

Diol loses H on both sides Dicarboxylic acids lose OH on both sides Can join in long chains H + OH lost forms water molecules

Question 37

Draw reaction of ethanedioic acid and ethanediol

Answer 37

-draw it

Question 38

Biodegradable polyesters

Answer 38

Biopolyesters -e.g. made from lactic acid