Brown's GCSE/IGCSE KS4 science-CHEMISTRY Revision Notes
Oil, useful products, environmental problems, introduction to
10. Carboxylic acids and esters
Carboxylic acids are a group of
organic compounds which have weakly acidic properties. The react with
bases/alkalis to for salts and release carbon dioxide from carbonates. They
react with alcohols (another organic series of compounds) to form organic
compounds called esters which are used as solvents and components in perfumes
and food flavourings.
Index of KS4 Science GCSE/IGCSE
Chemistry Oil & Organic Chemistry Pages: 1.
Fossil Fuels : 2. Fractional distillation of crude oil & uses of fractions : 3.
ALKANES - saturated hydrocarbons and combustion : 4.
Pollution, carbon monoxide, nitrogen oxides, what
makes a good fuel?, climate change-global warming :
5. Alkenes - unsaturated hydrocarbons :
6. Cracking - a problem of supply and demand, other products :
7. Polymers, plastics, uses and problems :
8. Introduction to Organic Chemistry - Why so many series of
organic compounds? : 9. Alcohols - Ethanol
- properties, reactions, biofuels :
10. Carboxylic acids and esters : 11. Addition
polymers and condensation polymers :
12. Natural Molecules - carbohydrates - sugars
- starch : 13. Amino acids, proteins,
enzymes & chromatography : 14. Oils, fats,
margarine and soaps :
15. Vitamins, drugs-analgesic medicines & food
additives and aspects of cooking chemistry! : 16. Ozone, CFC's and free
radicals : 17. Extra notes, ideas and links on
Global Warming and Climate Change : Multiple Choice and Gap-Fill Quizzes:
m/c QUIZ on Oil Products (GCSE/IGCSE easier-foundation-level)
m/c QUIZ on Oil Products (GCSE/IGCSE harder-higher-level) :
IGCSE/GCSE m/c QUIZ on other Aspects of Organic Chemistry
3 Easy linked GCSE/IGCSE Oil Products word-fill worksheets
CARBOXYLIC ACIDS and ESTERS
- other families of organic compounds
We find members of the homologous series called
carboxylic acids in fruits and in vinegar and many
in fragrances and food additives as carboxylic acid derivatives called esters. (
preparation and uses of esters).
- Carboxylic acids
form another homologous series
and have the functional group -COOH.
structures of the first three members are given below: Names end in
methanoic acid (old
name 'formic acid')
- ethanoic acid
(old name 'acetic acid', in vinegar)
- propanoic acid
(old name 'propionic acid')
contains ethanoic acid (old name 'acetic acid')
- Ethanoic acid can be manufactured on a large
scale by oxidising the alcohol ethanol.
- It is used as a
preservative and in food flavourings.
acid is used in the manufacture of the fibre, acetate rayon.
fruits like oranges and lemons and many soft drinks contain the
tri-carboxylic acid citric acid. and
contribute to the 'tarter' or 'sour' taste of fruit. The molecule contains
three acidic carboxylic acid groups -COOH.
- Citric acid is a natural
preservative (E330 on food labels) and is found in the largest
quantities in lemons, limes and grapefruit. It is an anti-oxidant.
Metal salts from citric acid, i.e. citrates, are used in dietary
supplements to deliver trace metal minerals in a biologically
available/absorbable chemical form.
- Citric acid can be
used in baking powder to react with sodium bicarbonate giving the raising
action from carbon dioxide gas formation. The same combination can be used
to give the fizzy drink effect in medicines like ant-acid stomach
- Aspirin is a carboxylic acid. Aspirin is a
drug used for pain relief and is taken regularly by those at risk from
heart attacks (see also
- Ascorbic acid (vitamin C) is another carboxylic
acid and is present in fresh fruit and vegetables
and is vital for good health AND the body cannot synthesise it, so you
must eat fruit and vegetables regularly!
- A lack of vitamin C can cause the
disease scurvy. The symptoms of scurvy are skin sores, spongy gums
and bleeding from mucous membranes. This is one example of malnutrition
diseases caused by a vitamin deficiency in a diet.
- Carboxylic acids are weak acids, typically
solutions are around pH 3 (yellow-orange-pink with universal indicator).
They are called weak acids because only a
few % of the molecules in aqueous ionise to release protons (hydrogen
- e.g. for ethanoic acid (vinegar)
- 98% CH3COOH(aq) <==> CH3COO-(aq)
+ H+(aq) 2%
- [ see theory
of acids and bases]
- They react and are
neutralised by bases
(insoluble or soluble - alkalis and carbonates) ... with examples ...
- metals react to form salts and
- ethanoic acid + magnesium ==>
magnesium ethanoate + hydrogen
- 2CH3COOH + Mg ==>
(CH3COO)2Mg + H2
- alkalis (soluble bases)
react to form a carboxylic acid salt
and water e.g.
- ethanoic acid + sodium hydroxide
==> sodium ethanoate + water
- CH3COOH + NaOH ==>
- OR ethanoic acid + potassium hydroxide
==> potassium ethanoate + water
- CH3COOH + KOH ==>
- insoluble bases dissolve
and react to form
salt and water e.g.
- zinc oxide + ethanoic acid ==>
zinc ethanoate + water
- ZnO + 2CH3COOH ==>
(CH3COO)2Zn + H2O
- carbonate and hydrogencarbonate
to produce a carboxylic acid salt, water and carbon dioxide e.g.
- ethanoic acid + sodium hydrogen
carbonate ==> sodium ethanoate + water + carbon dioxide
- CH3COOH + NaHCO3
==> CH3COONa + H2O + CO2
- OR ethanoic acid + sodium carbonate
==> sodium ethanoate + water + carbon dioxide
- 2CH3COOH +
Na2CO3 ==> 2CH3COONa
+ H2O + CO2
- OR propanoic acid + sodium carbonate
==> sodium propanoate + water + carbon dioxide
- 2CH3CH2COOH +
Na2CO3 ==> 2CH3CH2COONa
+ H2O + CO2
- aqueous ammonia solution
forms ammonium salts e.g.
- methanoic acid + ammonia ==>
- HCOOH + NH3
- ethanoic acid + ammonia ==>
- CH3COOH + NH3
- Strictly speaking, ammonium
hydroxide doesn't really exist, but in older texts you will find these
reactions written in this way e.g.
- propanoic acid + ammonium
hydroxide ==> ammonium propanoate + water
- CH3CH2COOH + NH4OH
==> CH3CH2COONH4 + H2O
ESTERS: Carboxylic acids react with alcohols
members of another homologous series called esters. Concentrated
sulphuric acid acts as a catalyst in this reaction.
- sometimes more simply written as
- CH3COOH + CH3CH2OH
CH3COOCH2CH3 + H2O
- For more details see the
preparation & formation of ethyl ethanoate and other esters in
section 9 for lots more details.
- Structures of other esters
made from ethanoic acid:
methyl ethanoate using methanol, and
ethanoate from using propan-1-ol (n-propyl alcohol).
- and what would the structure of their
original alcohols be and what would the structure of butyl ethanoate
- Esters occur widely in
nature and are usually sweet/pleasant smelling liquids and widely used as fragrances
(e.g. perfumes) and
food flavourings. Natural
substances are used in many cosmetics but many mixtures contain
synthetic organic compounds.
- Examples of plant ester sources:
- Lavender oil essence is distilled
from the lavender plant
- Examples of flavouring esters:
- Pear drop sweet essence is an ester.
- Factors affecting perfume
design e.g. using esters:
- Designing a perfume - several issues
to address by way of design factors.
- The perfume needs to be a mixture of
compounds to give a prolonged perfumery effect.
- The perfumer chemist has to design the
mixture to give a particular fragrance which includes ...
- the top note - the first fragrant
molecule to be released,
- and the low note, the last molecule to be
Multiple Choice Quizzes and Worksheets
KS4 Science GCSE/IGCSE m/c QUIZ on Oil Products
KS4 Science GCSE/IGCSE m/c QUIZ on Oil Products
KS4 Science GCSE/IGCSE m/c QUIZ on other aspects of Organic Chemistry
3 linked easy Oil Products gap-fill quiz worksheets
ALSO gap-fill ('word-fill') exercises
originally written for ...
... AQA GCSE Science
Useful products from
crude oil AND
... OCR 21st C GCSE Science
Worksheet gap-fill C1.1c Air
pollutants etc ...
... Edexcel 360 GCSE Science
Crude Oil and its Fractional distillation
... each set are interlinked,
so clicking on one of the above leads to a sequence of several quizzes
Level Organic Chemistry revision notes
Revise KS4 Science GCSE/IGCSE/O level
Chemistry Revision-Information Study Notes for revising for AQA GCSE Science, Edexcel
360Science/IGCSE Chemistry & OCR 21stC Science, OCR Gateway Science WJEC/CBAC
GCSE science-chemistry CCEA/CEA GCSE science-chemistry
(and courses equal to US grades 8, 9, 10)
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