basic concept in fats and natural rubber

2. Saturated fat Fat molecule that has no
carbon –carbon double
bonds
Unsaturated fat Fat molecule that has at
least ONE carbon –carbon
double bonds

3. Oil Liquid at room temperature
and found in plants
Fat Solid at room temperature
and found in animals

4. Glycerol An alcohol that has 3 hydroxyl
group in 1 molecule
Fatty Carboxylic acid that has a
acids long chain carbon, about 10
to 20 carbon atoms and has
only one carboxyl group

5. Examples Coconut oil, corn oil
of oils
Examples
of fats Meat, butter, cheese

6. Examples of
saturated
Meat, butter, cheese
fats
Examples of
unsaturated Soybeans, peanuts, sunflower
fats seeds, maize

7. cholesterol White, fatty substance that
make blood vessels become
hard and narrow
Hydrogenation Addition of hydrogens to
the double bonds between
2 carbon atoms

8. a) State 2 similarities
between fats and oils?
•Both are esters
•Both occur naturally in
living tissues of
organisms

9. b) Fill in the table below to list
differences between oils and fats
Oils Fats
a)sources Plants and Animals
animals
• Physical liquid solid
state
a)Melting Lower than Higher
point 20 oC than 20 o C

10. c) Fill in the table below to list differences
between saturated and unsaturated fats
Unsaturated Saturated fats
fats ( C=C) (C-C)
a)Proportion of More More saturated
molecules unsaturated molecules than
between molecules than unsaturated
saturated and saturated molecules
unsaturated molecules
fats

11. c) Fill in the table below to list differences
•between saturated and unsaturated fats
Unsaturated Saturated fats
fats ( C=C) (C-C
b) Physical Mostly Mostly solids
state at liquids
room temp

12. c) Fill in the table below to list differences
•between saturated and unsaturated fats
Unsaturated Saturated fats
fats ( C=C) (C-C)
c) Melting Lower Higher melting
point melting point
point

13. c) Fill in the table below to list differences
•between saturated and unsaturated fats
Unsaturated Saturated
fats ( C=C) fats
d) sources Plants and (C-C)
Animals
vegetables

14. d) Why do unsaturated
fats turn bad or spoil
easily?
They contain carbon-carbon
double bond that can easily
reacts in the air.

15. e) Explain how unsaturated fats
can be changed to saturated fats?
•Through catalytic hydrogenation
Where carbon-carbon double bond
absorbs one mole hydrogen
•The process is carried out by
bubbling hydrogen gas through hot
liquid oil in the presence of fine
particles of nickel catalyst at temp of
200 o C and pressure 4 atm

16. Answer the following questions
•FATS
Oils and fats are esters
Carboxylic + Alcohol  Fats or + water
acids
oil
Glycerol or 1,2,3-
Fatty acid propanetriol
Has a very long chain carbon,
(about 10-20 atoms)
Examples, palmitic acids, stearic
acids, linoleic acids

17. a) From diagram above, what is
glycerol?Draw its molecular formula
• Glycerol is an
alcohol with
three hydroxyl
group in one
molecule of
glycerol

18. b) From diagram above, what is the
difference between a fat molecule and a
fatty acid molecule?
•A fat molecule is formed when long-
chained carboxylic acid reacts with
alcohol with three OH-groups (glycerol)
•A fatty acid molecule is carboxylic acid
molecule that has a long chain carbon
atom ( about 10- 20 atoms)

19. c) Hexanoic acid and pentanol react
together to form a product. Name the
product formed and state its
homologous series
Name of product: pentyl hexanoate
Homologous series : ester

20. •Can hexanoic acid and pentanol react
together to form Fat or Oil? Explain your
answer
No, because hexanoic acid is a
short chain carboxylic acid with
carbon atoms only 6 atoms and
pentanol is not a glycerol

21. •Can decanoic acid
and glycerol react
together to form Fat or
Oil? Explain your answer
Yes, because decanoic
acid is a long chain
carboxylic acid with carbon
atom is 10 and reacts with
glycerol

22. a) List examples of natural polymers
and their monomers

23. •Complete the structural formula of
natural rubber in the diagram below

24. •Or draw the structural formula of
natural rubber in a simpler form

25. *** draw structure of its monomer!
2-METHYLBUT-1,3-DIENE

26. b) State the properties of natural
rubber
•White ……SOLID……… at room
temperature
•Elasticity that ………DECREASE
…… overtime
•Soft
•Sensitive to …………HEAT..

27. •State 3 uses of natural rubber
•In the making of tyres, footwear,
rubber threads, rubber foam,
conveyor belts and bitumen roads
•Buildings built on rubber blocks or
rubber bearings to help absorb
vibration
•Making of gloves, tubes and hoses

28. •Latex is a …………COLLOID…………
•It consists of ……RUBBER PARTICLES
particles dispersed in ……WATER…
•Each rubber particle is made-up many long-
chain ………RUBBER………..molecules
enclosed by a ………PROTEIN..-like membrane
which is ……NEGATIVELY-charged

30. Process 1
The repulsion between the ……
NEGATIVELY …..charged particles
prevent the ……RUBBER particles
from coming close to each OTHER
THEREFORE LATEX COULD NOT
COAGULATE

31. Process 2
•When an ACID is added to latex, OR
when latex is exposed to AIR , the
BACTERIA ..from the air enters the
latex and produce LACTIC acid that
form HYDROGEN …ions. This
HYDROGEN ….ions neutralize the
NEGATIVE charges on the protein
membrane.

32. Process 3
•The rubber PARTICLES can now
come close together. This enable
them to COLLIDE .with one another
resulting in the BREAKAGE of the
protein membranes.

33. Process 4
•a) the collision between the rubber
particles cause the membrane to break
•B) the rubber molecules inside the
membranes are now set free
Draw diagram .

34. Process 5
•The rubber molecules COMBINE ……
with one each other and clump
together . The latex is now coagulated

35. iv) Describe how to prevent the
coagulation of latex
By adding AMMONIA ….solution, that
contains …HYDROXIDE ……….ions
which …NEUTRALIZE ………. the acid
produced by the bacteria . Therefore
rubber particles remain …
NEGATIVELY…… charged and the
coagulation is PREVENTED

36. VULCANISED RUBBER
a) What is meant by vulcanization
of rubber?
ADDITION OF SULPHUR TO
RUBBER AT 140 OC AND HIGH
PRESSURE IN THE PRESENCE
OF ZINC OXIDE AS THE
CATALYST

37. b) In industry, how does the
vulcanization of rubber is carried
out?
By heating latex with SULPHUR
or a solution of sulphur
monochloride in methylbenzene
as solvent

38. c) Describe how sulphur atoms change
the properties of rubber
•In vulcanization , sulphur ….atoms
form cross-link …between rubber
molecules
•These cross – LINK prevent rubber
MOLECULES from sliding too much
when STRETCHED
•The rubber molecules return to their
ORIGINAL ….. position after being
stretched.

39. d) Draw cross-linkage of sulphur

40. e) Compare and contrast the
properties of vulcanized and
unvulcanised rubber
•Similarities
Both are ELASTIC
Both are HEAT AND
ELECTRICAL INSULATORS

41. •Differences
Vulcanised Differences Unvulcanis
ed rubber
More elastic Elasticity LESS
elastic
Harder Hardness SOFTER
More tensile Tensile strength LESS
strength tensile
strength

42. •Differences
Vulcanised Differences Unvulcanis
ed rubber
More Resistance to LESS
resistance to heat resistance
heat to heat
LESS SOLUBLE Effect of MORE
organic solvents SOLUBLE

43. f) State one advantage of natural
rubber over synthetic rubber
Only natural rubber can take the
tremendous STRESS, STRENGH
AND HEAT ………produced
during landing and taking off of an
aero plane