Alcohols 1

8/18/2019 Alcohols 1

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ALKANE

ALKENE

ALCOHOL

CARBOXYLIC ACID

ESTER


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ALCOHOLS


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LEARNING

OUTCOMES :

Students should be able to :

State the general formula of alcohols

Identify the functional group of alcohols

List the names and the molecular formulae of the

first four alcoholsDraw structural formulae for isomers of propanol and

butanol

Name isomers of propanol and butanol using IUPAC

nomenclatureDescribe the industrial production of ethanol

Describe the preparation of ethanol in the laboratory


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alcohols

Contain

carbon,

hydrogenand oxygen

Non -

hydrocarbons

General

formula

Functional

group


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H

H

H

HC O


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A functional groupis a

special group of atoms

attached to an organic

molecule.


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Functional Group :hydroxyl group, -OH

General Formula :CnH2n+1OH


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NAMING ALCOHOLS

The names of straight chain alcohols can be

derived fromalkanes.

Alcohols are named by replacing the ending–e

from the name of the alkane with– ol.


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NAMING

ALCOHOL

n 1 2 3 4 5

Root

name

Meth- Eth- Prop- But- Pent-

n 6 7 8 9 10

Root

name

Hex- Hept- Oct- Non- Dec-

Family name - ol


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EXAMPLE:

Name of alkane : propane

Name of alcohol : propanol

Position of hydroxyl group : carbon 1

Full name of alcohol : propan-1-ol


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Member Number

of

carbon

atoms, n

Molecular

formula

Structural

formula

Name of

correspond-

ing alkane

Name of

alcohol

CH3OH

C2H5OH

C3H7OH

Methane Methanol

Propanol

Ethanol

Propane

Ethane

1 1

2 2

3 3


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ISOMERS OF ALCOHOLS

Exists in alcohols with 3 or more carbon atoms.

Results from:a) branching of the carbon chainExamples : C4H9OH

b) Different locations of the hydroxyl group

Example: C3H7OH


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NAMING ISOMER OF ALCOHOL

Step 1:Find thelongest continuouscarbon chain

containing the hydroxyl group

Step 2:Name the longest chain bysubstituting theending–olfor the–e of the correspondingalkane

Step 3:Numberthe carbon atomsbeginning at the

end nearerto thehydroxyl group– ensure thathydroxyl group will be given the lowest possible

number


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NAMING ISOMER OF ALCOHOL

Step 4:Identifythepositionofhydroxyl groupby

writing the number of carbon atom to which it is

attached in front of the ending –ol

Step 5:Locate the name all attachedalkyl groups

Step 6:Complete name for the alcohol by

combiningthethree component parts together.Write the name as asingle word.


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Which of the following represents a structural formula of an alcohol ?


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Name the structure shown below.


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The molecular formula of an alcohol that

contains three carbon atom is

A C3H6O

B C3H7OH

C C3H8OH

D C3H9O

What is the functional group for alcohol ?

What is the general formula for propanol ?

Draw the structural formulae of 2-methylbutan-

2-ol ?


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Which of the following are isomers of butanol ?

I Butan-3-ol

II2-methylpropan-2-ol

III2-methylpropan-1-ol

IV3-methylbutn-2-ol

A I and IV only

B II and III only

C I, II and III onlyD II, III and IV only


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INDUSTRIAL PRODUCTION OF

ETHANOL

Ethanol , C2H5OH is one of the most important

alcohols.

It is manufactured on a large scale by two main

processes :

From sugars and starch byfermentation

From petroleum fractions byhydration


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MAKING ETHANOL BY

FERMENTATION

The fermentation process is ananaerobic which

means it takes place in the absence of oxygen.

Yeast is added tosugar or starchand left in awarm place for several days in the absence of air.

Yeast releasesenzyme.

Enzymes break down the sugars and starches

into glucose, C6H12O6


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In the fermentation process, the enzyme called

zymase.

Zymase slowly decomposes the glucose C6H12O6 to

form ethanol, C2H5OH and carbon dioxide, CO2.

C6H12O6 → 2CH3CH2OH + 2CO2

Temperature : 18 – 20oC

Catalyst : yeast (zymase)Other condition: absence of oxygen


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Whenthe concentration of ethanolformed

reaches about15%, theyeast diesand the

fermentation stops.

It is impossible to produce pure ethanol by

natural fermentation.

Ethanol is then purified byfractional

distillation


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MAKING ETHANOL BY HYDRATION

Is calledcatalytic hydration

Anaddition reactioncombines ethene, C2H4 with

water to produce ethanol.

CH2=CH2 + H2O → CH3- CH2OH

steam

Temperature : 300OC Pressure :60 atm

Catalyst :phosphoric acid, H3PO4


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What is the process involved in the conversion of

propene to propanol ?


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Diagram shows the

set up of the

apparatus for the

fermentation process. Which of the following is the product obtain

from this process ?

I Ethanol

II Water

III Carbon dioxide

IV Ethanoic acid

A I and II only

B I and III only

C II and IV only

D III and IV only


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LABORATORY PREPARATION OF ETHANOL

Aim: To produce pure ethanol through thefermentation and distillation process

Materials: Glucose solution, yeast, lime water,

pipe water , porcelain pieces

Apparatus: 250cm3 conical flask, test tube,

rubber stopper with delivery tube, beaker,

spatula, round-bottomed flask, wire gauze, tripodstand, Bunsen burner, thermometer, Liebig

condenser, rubber tube, retort stand


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RE

100cm3 of glucose solution is poured into the

conical flask

Add two spatulas of yeast into the glucose

solution

Prepare the apparatus arrangement as shown in

Diagram (a)

Leave the materials and apparatus at roomtemperature for two to three days

Observe the changes that occur at the end of the

activity


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Pour the products of the fermentation into the

distillation flask and heat it[Diagram b)

Collect the clear liquid that is distilled out from

theLiebig condenser

Record thetemperatureon the thermometer

when the clear liquid is distilled out

Observe the clear liquid and physical state of the

distilled product


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OBSERVATION :

A colourless gasis liberated during the

fermentation process.

The gas turnslime water milky

A colourless liquid is obtained during the

fractional distillation


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CONCLUSION :

Ethanol can be obtained by the

fermentation of glucose found in sugars or

carbohydrate


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The diagram shows the experimental set-up to

produce compound X.

What is compound X ? A Ethane C Ethanol

B Ethene D Ethanoic acid


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SUMMARY :

What is the general formula for alcohol ?

What is the functional group for alcohol ?

What is isomer ?

What is the processes to produce ethanol ?


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Physical propertiesof alcohols

Is a liquid

at room

conditions

Verysoluble in

water

Low boiling

point


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Is a liquid at

room

conditions

Physical

propertiesof ethanol

Highly

volatile

colourless

Low boiling

point

Very soluble

in water

Has

sharpsmell


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CHEMICAL PROPERTIES OF

ETHANOL

CombustionOxidationdehydration


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COMBUSTION

Alcohols are very flammable substances.

Complete combustion of ethanol produces carbon

dioxide and water

2H5OH(l) + 2O2(g)→ 2CO2(g) + 3H2O(l)

Ethanol releases lots of heat

This makes ethanol suitable for use as a fuel as a clean fuel because it does not release

pollutants into the atmosphere


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OXIDATION

Oxidation reaction isvery common

Occurs when asubstance combines withoxygen

Oxidizing agentsare needed to carry out the

oxidation reactions


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COMMON OXIDIZING AGENT

Acidified potassium dichromate(VI), K2Cr2O7

solution

Acidified potassium manganate (VII), KMnO4

solution


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Alcohols can be easilyoxidized to carboxylic

acids( a family of organic compounds with –COOH

group)

When acidified potassium dichromate(VI) ,

K2Cr2O7solution is addedto ethanol themixture

is warmed

It turns fromorange to green

Shows it has oxidized the ethanol to form

ethanoic acid, CH3COOH


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-CH2OH group hasgained an extra oxygen

atom

Changed into a–COOH group

Number ofcarbon atoms remains unchanged


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If acidified potassium manganate (VII), KMnO4

solution is used

Changes colour frompurple to colourless


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DEHYDRATION

Remove waterfrom a compound

In the dehydration alcohol, a molecule of water is

eliminated from each alcohol molecule

Alcohol moleculebecomes an alkenemolecule

This reaction can be used to make alkenes from

alcohol


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Elimination of a molecule of water results in the

formation of a carbon-carbon double bond

Noticed that the hydroxyl group, -OH is removedtogether with a hydrogen atom


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The ethene produced can be detected by the

following tests :

Decolourizesreddish-brown bromine water

Decolourizespurple acidified potassium

manganate(VII), KMnO4 solution


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Two methods to carry out the dehydration in

school laboratory :

Ethanol vapour ispassed over a heated

catalystsuch as unglazed procelain chips,

porous pot pumice stone or aluminium oxide, Al2O3

Ethanol is heated underreflux at 170o

Cwithexcess concentratedsulphuric acid


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HOW DO OTHER ALCOHOLS REACT ?

Ethanol is a member of the alcohol

homologous series

All the other members of this series have thesame functional groupwhich is the hydroxyl

group

Hence, other members of the family should beable toexhibit similar chemical properties

as ethanol


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SUMMARY

A l


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As asolvent in

perfumes

CosmeticsToiletries

Properties of alcohol:

Colourless

Volatile

Miscible with water

Good organic solvent

Asathinnerin


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As athinner in

lacquer

varnish

shellac

Ink


Colourless

Volatile

Miscible with waterGood organic solvent


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As acleaner for

Compact disc

Video cassette recorder head


Colourless Volatile

Miscible with water

Good organic solvent

A f l


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As afuel

Clean fuel

biofuelgasohol


Volatile

Highly flammable

High heat content

A t ilith f t f


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As araw materialin the manufacture for

vinegar

fibreexplosive

plastic


Chemically reactive


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As araw materialto make

pharmaceutical products

tinctureantiseptic

Cough syrup

Rubbing alcohol


Volatile

Good solvent

antiseptic


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ALCOHOL – MISUSE AND ABUSE

Human consuming ethanol in the form of

alcoholic drinksfor centuries even though

doctors have reminded users about theharmful

effects of ethanol


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Ethanol acts as adepressant on the central

nervous system

Itslows downphysical and mental activity

Causes person tofeel highand tolose all

shyness

Person isno longer in controlof his actions

Lose both physical and mental control

If driving a car, he can causefatal accidents


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Alcohol is alsoaddictive

Long term excessive consumption will turn a

person into analcoholic

Alcoholism createssocial problemsfor thefamily and society

causechronic liver disease(cirrhosis) ,brain

damageand leading to death


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CARBOXYLIC ACID

Examples of common carboxylic acids :

Acetic acid in vinegar

Lactic acid in sour milkCitric acid in citrus fruits

Ascorbic acid is vitamin C

Salicylic acid is used to make aspirin


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Containcarbon, hydrogen and oxygen

Functional group :-COOH , carboxyl group

General formula :CnH2n+1COOH (n= 0,1,2,3…)


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NAMING CARBOXYLIC ACID

Straight-chain carboxylic acids are named by

replacing the –efrom alkane namewith –oic

acid


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Step 1 : determinefunctional group / family

Step 2 : find thelongest continuous carbon

Step 3 :name the longest chain by replacing ending

–e of alkane name with –oic acid

Step 4 :number the carbon atomsin the longest

chain beginning at the carboxyl group

Step 5 : locate and name all attachedalkyl group


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List the names and molecular formulae of firstfour members of carboxylic acid

Draw structural formulae of the first four

members of carboxylic acid and name them usingthe IUPAC nomenclature


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MAKING ETHANOIC ACID

Most common: oxidation of an alcohol

Carried out byrefluxing ethanolwith anoxidizing agent such as acidified potassium

dichromate(VI), K2Cr2O7 solution or potassium

manganate(VII), KMnO4 solution


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The flask is fitted with anuprightcondenser to

prevent the loss of a volatile liquidbyvaporization.

This method of retaining a volatile liquid during

heating is calledrefluxing

PROPERTIES


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PROPERTIES

Colourless liquidsat room temperature

Havesharp or unpleasant odours

Larger carboxylic acidmolecules that have ten

or more carbon atoms arewax-like solids andhave little or no odour

Boiling point higherthan alkane

Increase with increasing number of carbon atoms

per molecule

CHEMICAL PROPERTIES


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Acid properties :

Ethanoic acid is a weakmonoprotic acid

Only hydrogen atom in the carboxyl group –COOH

can ionize in water toproduce hydrogen ions, H+

Weak acid,partial dissociationoccurs to produce

low concentration of hydrogen ions.

The presence of hydrogen ionsturn moist bluelitmus paper red

Reacts slowlywith metals, bases and carbonates


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Reactions with metals

Reactions with bases

Reactions with carbonates

Reactions with alcohols

REACTIONS WITH


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METALS

Dilute ethanoic acid reacts with reactive metals

to produce a salt and hydrogen.

Carboxylic acid + reactive metal →

carboxylate salt + hydrogen

2CH3COOH + Zn → Zn(CH3COO)2 + H2

A colourless solution of zinc ethanoate is formed


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REACTION WITH BASES

Dilute ethanoic acid neutralizes alkalis to give an

organic salt and water

CH3COOH + NaOH → CH3COONa + H2O

Carboxylic acid + base → carboxylate salt +

water


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REACTIONS WITH CARBONATES

Acids reacts with metal carbonate to produce a salt,

carbon dioxide and water

2CH3COOH +CaCO3→Ca(CH3COO)2 +CO2 + H2O

Carboxylic acid +metal carbonate → carboxylate salt +

carbon dioxide + water


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REACTS WITH ALCOHOLS

Carboxylic acid reacts with alcohol to form an

ester and water

Reaction which produces an ester is called

esterification

CH3COOH + C4H9OH → CH3COOC4H9 + H2O

Carboxylic acid + alcohol → ester + water

CHEMICALREACTIONSOFOTHER


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CHEMICAL REACTIONS OF OTHER

CARBOXYLIC ACID

All member have thesame functional groupwhich

is carboxyl group, -COOH

Therefore, other carboxylic acids undergo thesamechemical reactions

Carboxylic acid + reactive metal → carboxylate salt + hydrogen

Carboxylic acid + base → carboxylate salt + water Carboxylic acid +metal carbonate→carboxylate salt +CO2 + H2O



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USES OF CARBOXYLIC ACIDS

Ethanoic acid: most important carboxylic acid

Ethanoic acid most commonly calledacetic acid

Is a major industrial chemical

Use in food as aflavouringand as apreservative

Vinegar is a solution containing 5% ethanoic acid.


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Ethanoic acid is also used with other chemicals to make :

Drugs

Dyes

Paints

Insecticides

plastics


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In the rubber industry,methanoic acid

HCOOH (formic acid ) is used tocoagulalate

latex.

Fatty acidsare long-chain carboxylic acids used

inmaking soaps.

Carboxylic acidsare used in the manufacture

ofpolyesters and polyamideswhich arefibres

used in the textile industry.

Benzoic acidis apreservative in foods


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ESTER

S


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S

Organic compound that are widely found in nature

Most are found in fruits.

Containhydrogen,carbon andoxygen

General formula isCnH2n+1COOHCmH2m+1

n= 0,1,2,3,… m= 1,2,3,…

Fuctional group: -COO(carboxylate group)


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NAMING ESTERS

Name of alkyl

group from alcohol

Name of

carboxylate group

from carboxylateacid


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FORMATION OF ESTERS

Esterification


Catalyst : concentrated H2SO4

Example :Propanoic acid + ethanol → ethyl propanoate + water

PHYSICAL PROPERTIES OF

ESTERS


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ESTERS

Sweet pleasant smell

Colourless liquids

Boiling points much lower than carboxylic acids

of similar molecular masses

Volatile

Slightly soluble in water but readily dissolve in

organic solvents


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NATURAL SOURCES OF ESTERS

Found in fruits and flowers

IUPACPROVIDESINFORMATION


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IUPAC PROVIDES INFORMATION

ABOUT :

Whichhomologous seriesit belongs to

Itsfunctional group

Thetotal number of carbonatoms

present

Itsmolecular andstructural formulae

USES OF ESTERS IN EVERYDAY


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LIFE

Preparation ofcosmetics and perfumes

Asfood additivesto enhance the flavour and

smell of food


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Solvents for :

Sunburn lotions

Nail polish removers

Glues

Production of soaps and

detergents

Production of polyester

(synthetic fabrics)

Simple esters Larger esters

ARTIFICIALFRUITFLAVOURINGS


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ARTIFICIAL FRUIT FLAVOURINGS

Ester Formula Flavour

n-pentyl ethanoate CH3COOC5H11 Bananas

Ethyl butanoate C3H7COOC2H5 Pineapples

Octyl ethanoate CH3COOC8H17 Oranges

Isoamyl isovalerate C4H9COOC5H11 Apples

Methyl salicylate C6H4(OH)(COOCH3) Oil of wintergreen


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USES OF ESTER IN EVERYDAY LIFE


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DESCENDING THE

HOMOLOGOUS SERIES

First member

Second member

Third member As the number of carbon atoms per molecule increases : Melting point increases

Boiling point increases

Density increases

Viscosity increases

Volatility decreases


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FATS


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WHAT ARE FATS AND OILS ?

Chemically very similar but differ in their physical

states.

Fats found in animals– solid at room temperatureExamples : butter and tallow

Fats from plants are normally liquids – calledoil

Examples : palm oil, sunflower oil and coconut oil


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Fat formed from :

carboxylic acid (fatty acids)

alcohol (glycerol @ propane-1,2,3-triol)

WHY ARE FATS AND OILSIMPORTANTTOOURBODYPROCESS


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IMPORTANT TO OUR BODY PROCESS

?

Provide us :

Energy

NutrientsThermal insulation

Protection to internal organs-kidney is protected

by a layer of fat

PROTECTIONANDSTRUCTURAL


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PROTECTION AND STRUCTURAL

ROLE

Surround and protectvital internal organsin

our body

Form theprotective membraneof each cell


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SOURCES OF ENERGY

Store energy asbody fat

Release energy during cell respiration


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THERMAL INSULATION

Fats under the skin act as a thermal insulator

which helps tokeep our body warm


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SOURCE OF NUTRIENTS

Help to carryfat-soluble vitaminslike

vitamins A, D, E and K, which essential for good

health

SATURATED AND UNSATURATED


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FATS

Affect by the parent fatty acids

Saturated fatty acid has all carbon atoms joined

together bycarbon carbon single bonds.

Example : palmitic acid


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UNSATURATED FATS

Unsaturated fatty acid that has carbon-carbondouble bonds

Monounsaturated :

has one carbon-carbon double bond

Example : oleic acid

Polyunsaturated :Has more than one carbon-carbon double bond

Example : linoleic acid (2), linolenic acid (3)


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Saturated fats :Contain esters of glycerol and saturated fatty

acids

Unsaturated fats :

Contain esters of glycerol and unsaturated fatty

acids

CONVERTING UNSATURATED FATS


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TO SATURATED FATS

Catalytichydrogenation

Bubbling hydrogen gas through hot liquid oil

Catalyst:nickelTemperature:200oC

Pressure:4 atm


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EFFECT FATS ON HEALTH

High in energy – result in obesity- heart diseaseand diabetes

Saturated fats- raise the level of cholesterol-

causes fatty deposits-raise blood pressure

Hardening of the arteries occurs-arteriosclerosis

and cause heart attack

INDUSTRIAL EXTRACTION OF PALM


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OIL

Two type of oil

-pulp palm oil

-kernelor seed palm kernel oil


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ADVANTAGES OF USING PALM OIL


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IN FOOD PRODUCTION

Cheaper oil : less expensive than other vegetable

oils

Better oil : can withstand heat and resistoxidation (antioxidant) when cooked at high

temperature

OIL :


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Easy digested and absorbed

Does not cause a rise inblood cholesterol level

Does not containcholesterol

Containsomega-6 fatty acid (linoleic acid)Reduce the incidence of coronary heart disease

Contains the highest amounts of natural antioxidants

(vitamin A and E)

To prevent aging, cancer, arteriosclerosis

PALM OIL INDUSTRY IN MALAYSIA


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Malaysia is the world’s largest producer and

exporter of palm oil contributing 58% of the

world’s production

Importance of research :

Develop new products and uses for palm oil

Research institutes :

PORIM – Palm Oil Research Institute of

Malyasia


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RESEARCH PROJECTS

Conversion of palm oil intobiofuels

Conversion of palm oil biomass intopulp and

paper

Production ofbiodegradable thermoplastics


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NATURAL

RUBBER


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NATURAL POLYMER

Polymer that exists naturally and is not made byman from chemical reactions

Natural polymer Monomer

Natural rubber Isoprene

Starch Glucose

Cellulose Glucose

protein Amino acid


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Cotton and woodare made up of cellulose

Wool and silkare protein that found in nature


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COAGULATION PROCESS OF

LATEX


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LATEX

Latex needs to be turned into a solid to be usedin daily purposes

This process is known ascoagulation

Latex is a colloid (aqueous solution)

It consists ofrubber particlesdispersed in

water


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Coagulation of latex will occur when it is exposed

to air

This is because thebacteria from the airenter

the latex.

Bacteria producelactic acidthat causes

coagulation

Due to the slow bacterial action, coagulationtakes longer time.

ALKALI IS ADDED TO LATEX TO

PREVENTCOAGULATION


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PREVENT COAGULATION

Latex can bepreserved in the liquidstate if

ammonia solution is added

Ammonia solution contains hydroxide ions. OH-

thatneutralize the acidproduced by the

bacteria.

Rubber particles remain negatively charged

Coagulation is prevented

PROPERTIESOFNATURALRUBBER


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PROPERTIES OF NATURAL RUBBER

White solidat room temperature

Elasticity decreasesover time

Easily oxidized by air

SoftSensitive to heat :

When heated, it becomes soft and sticky

When cooled , it becomes hard and brittle


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COMPARE AND CONTRAST THE PROPERTIES

OF VULCANIZED AND UNVULCANIZED


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RUBBER

Similarities :

Elastic

Heat and electrical insulator

DIFFERENCES


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Vulcanized

rubber

Differences Unvulcanized

rubber

More elastic Elasticity Less elastic

Harder Hardness Softer

Stonger Tensile strength Weaker

Can withstand

higher temperature

Resistance to heat Cannot withstand

higher temperature

Less easily oxidized Resistance to

oxidation

Easily oxidized

Does not become soft

and sticky easily

Effect of organic

solvent

Becomes soft and

sticky easily


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Vulcanization improve properties of natural

rubber due to the :

presence ofcross-linkage of

sulphur atoms between the

rubber molecules


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When vulcanized rubber is stretched and

released, thecross-linkage pull the chains

backto their original arrangement

This improves the elasticity and strength of the

rubber

The presence of sulphur cross-linkage increases

thesize of rubber molecules, making more

resistant to heat and organic solvents


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Vulcanized rubber has much lesser carbon-carbon double bond

- Higher resistance to oxidation

USESOFNATURALRUBBER


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USES OF NATURAL RUBBER

Making tyres

Footwear

Rubber threads

Rubber foamConveyor belts

Rubberized bitumen roads

Buildings in earthquake areas built onrubber

blocksorrubberbearings helpabsorb


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blocks or rubber bearings– help absorb

vibration

Itsimpermeability to gas and liquid – used in

gloves, tubes and hoses

Rubbercombine with other materials such assynthetic rubber and plastics– tougher while

maintaining their elasticity

*aircraft tyresmust be made fromnatural

rubber- can take tremendous stress, strength

and heat produced during landing and taking off


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Documents

Alcohols 1