spm chemistry form 5 chap 2

7/21/2019 SPM Chemistry Form 5 Chap 2

http://slidepdf.com/reader/full/spm-chemistry-form-5-chap-2 1/19

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SPM Chemistry Form 5 – Terminology and Concepts: Carbon Compounds

1. Organic compounds – carbon containing compounds with covalent bonds.2. Inorganic compounds – non-living things and usually do not contain carbon

but few carbon containing inorganic compounds such as CO2, CaCO and

!C".. #ydrocarbons – organic compounds that contain hydrogen and carbonatom only.

$. "on-hydrocarbons – organic compounds that contain other elements%o&ygen, nitrogen, iodine, phosphorus'

(. )aturated hydrocarbons – only single bonded %Carbon-Carbon'hydrocarbons.

*. +nsaturated hydrocarbons – at least one double triple bonded %Carbon-Carbon' hydrocarbons.

. Complete combustion – organic compounds burn completely which formCO2 and #2O.

. /&ample0 C2#(O# %l' O2 %g' – 2CO2 %g' #2O %l'

3. Incomplete combustion – organic compounds burn with limited supply ofO2 which form C %soot', CO, CO2 and #2O.

Homologous Series

#omologous series – organic compounds with similar formulae and properties. Ithave the physical properties that change gradually as the number of carbonatoms in a molecule increases.

CarbonCompounds

4eneral5ormula

5unctional group

6l7ane Cn#2n2 n 8 1, 2,, 9

Carbon-carbon singlebond- C – C -

6l7ene Cn#2n n 8 2, ,$, 9

Carbon-carbon doublebond- C 8 C -

6l7ynes Cn#2n-2 n 8 2, ,$, 9

Carbon-carbon triplebond- C 8 C -

6renes Cn#2n-* n 8 *, ,, 9

- C 8 C -delocalised free tomove around the ring

6lcohol Cn#2n1O# n 8 1, 2,, 9

#ydro&yl group- O#

Carbo&ylic 6cids Cn#2n1COO# n 8 :, 1, 2 Carbo&yl group- COO#

/sters Cn#2n1COOCm#2

m1

n 8 :, 1,2, 9m 8 1, 2,, 9

Carbo&ylate group- COO -

;s <ay !him )im =a7ar ;inda <uition Center



2

Sources of Hydrocarbon:1. Coal – from the lush vegetation that grew in warm shallow coastalswamps or dead plants slowly become roc7. ;ainly contains of hydrocarbon andsome sulphur and nitrogen. It is used to produce0 fertiliser, nylon, e&plosives andplastics.

2. Natural gas – from plants and animals and trapped between the layersof impervious roc7s %on top of petroleum'. ;ainly contains of methane gas and

other gas such as propane and butane. It is used for0 coo7ing, vehicle andgenerate electrical power.

. Petroleum – from plants and animals and trapped between the layers ofimpervious roc7s. It is a comple& mi&ture of al7anes, al7enes, aromatichydrocarbons and sulphur compound. <hese compounds can be separated byusing fractional distillation.

• > (?C – petroleum gas

• (?C – (?C – =etrol %gasoline'

• (?C – 1:?C – "aphtha

•

1:?C – 2:?C – !erosene• 2:?C – 2(:?C – @iesel

• 2(:?C – ::?C – Aubricating oil

• ::?C – (:?C – 5uel oil

• (:?C – BitumenuiD0 #ow many 7nown carbon compounds there are in the world nowE –/stimated to be around 1: million carbon compounds 7nown. #owever,theoretically the number could be way larger. %)ource0 Fi7ipedia'




$

1: dec-

<he longest continuous %straight chain' carbon chain is selected. Identify the number of carbon.

*. Su)' – functional group.

#omologousseries

5unctionalgroup

)u&

6l7ane - C – C - -ane

6l7ene - C 8 C - -ene

6lcohol – O# -ol

Carbo&ylic acid – COO# -oic

/ster – COO – -oate

. /&ample0 $-methylhept-2-ene.. =reG& Hoot )u&

*" Family of Hydrocarbon – #l+ane

1. 4eneral formula0 Cn#2n2

Fhere n 8 1, 2, , 9 %n 8 number of carbon'2. /ach carbon atom in al7anes is bonded to four other atoms by singlecovalent bonds.

6l7anes are saturated hydrocarbon.

"ame of al7ane ;olecular formula ofal7ane

;ethane C#$

/thane C2#*

=ropane C#

Butane C$#1:

=entane C(#12

#e&ane C*#1$

#eptane C#1*

Octane C#1

"onane C3#2:

@ecane C1:#22

Molecular formula is a chemical formula that shows the actual number of

atoms of each type of elementspresent in a molecule of the compound./&ample0 molecular formula of butane is C$#2J$2 8 C$#1:

"ame Condensed structural formula of al7ane

;ethane C#$

/thane C#C#

=ropane C#C#2C#

Butane C#C#2C#2C#

=entane C#C#2C#2C#2C#

#e&ane C#C#2C#2C#2C#2C#

#eptane C#C#2C#2C#2C#2C#2C#

Octane C#C#2C#2C#2C#2C#2C#2C#




(

"onane C#C#2C#2C#2C#2C#2C#2C#2C#

@ecane C#C#2C#2C#2C#2C#2C#2C#2C#2C#

Structural formula is a chemical formula that shows the atoms of elements arebonded%arrangement of atoms' together in a molecule by what types of bond.

. Physical properties of al7anes

"ame ;olecularformula

H;; @ensity%g cm-'

=hysical stateat 2(?C

;ethane C#$ 1* - 4as

/thane C2#* : - 4as

=ropane C# $$ - 4as

Butane C$#1: ( - 4as

=entane C(#12 2 :.* AiKuid

#e&ane C*#1$ * :.** AiKuid#eptane C#1* 1:: :.* AiKuid

Octane C#1 11$ :.: AiKuid

"onane C3#2: 12 :.2 AiKuid

@ecane C1:#22 1$2 :. AiKuid

6l7anes with more than 1 carbon atoms are solid. Solubility in ,ater – all members in al7anes are insoluble in water but

soluble in many organic solvent %benDene and ether'. -ensity of al+ane – the density of water is higher than density of al7ane.

Fhen going down the series, relative molecular mass of al7anesis higher due to the higher force of attraction between molecules and

al7ane molecules are pac7ed closer together. .lectrical conducti/ity – all members in al7anes do not conduct

electricity.6l7anes are covalent compounds and do not contain freely moving ions.

*oiling and melting points – all al7anes in general have low boilingpoints and melting points.6l7anes are held together by wea7 intermolecular forces.

$. Chemical properties of al7anes (eacti/ity of al+anes

6l7anes are less reactive %saturated hydrocarbon'.6l7anes have strong carbon-carbon %C – C' bonds and carbon-hydrogen %C

– #' bonds.6ll are single bonds which reKuire a lot of energy to brea7.




Butene C$# (* :.::2 4as

=entene C(#1: : :.*$: AiKuid

#e&ene C*#12 $ :.*(: AiKuid

#eptene C#1$ 3 :.*3: AiKuid

Octene C#1* 112 :.1*: AiKuid"onene C3#1 12* :.1: AiKuid

@ecene C1:#2: 1$: :.$: AiKuid

Solubility in ,ater – all members in al7enes are insoluble in water butsoluble in many organic solvent %benDene and ether'.

-ensity of al+ene – the density of water is higher than density of al7ene.Fhen going down the series, relative molecular mass of al7enesis higher due to the higher force of attraction between molecules andal7ene molecules are pac7ed closer together.

.lectrical conducti/ity – all members in al7enes do not conductelectricity.

6l7enes are covalent compounds and do not contain freely moving ions. *oiling and melting points – all al7enes in general have low boiling

points and melting points. 6l7enes are held together by wea7 attractiveforces between molecules %intermolecular forces' van der FaalsM force.Fhen going down the series, more energy is reKuired to overcome theattraction. #ence, the boiling and melting points increases.

(. Chemical properties of al7enes (eacti/ity of al+enes

6l7enes are more reactive %unsaturated hydrocarbon'.6l7enes have carbon-carbon %C 8 C' double bonds which is more reactivethan carbon-carbon %C-C' single bonds. 6ll the reaction occur at the doublebonds.

Combustion of al+enesComplete combustion of hydrocarbons %al7enes'C x # y % x y $' O2 – x CO2 y 2 #2OC2#$ O2 – 2CO2 2#2O%6l7enes burn with sootier Names than al7anes. It is becausethe percentage of carbon in al7ene molecules is higher than al7anemolecules and al7enes burn plenty of o&ygen to produce carbon dio&ideand water'Incomplete combustion occurs when insucient supply of o&ygenC2#$ O2 – 2C 2#2OC2#$ 2O2 – 2CO 2#2O

%<he Name in the incomplete combustion of al7enes is more smo7y thanal7anes' Polymerisation reaction of al+enes

=olymers are substances that many monomers are bonded together in arepeating seKuence.=olymerisation is small al7ene molecules %monomers' are oinedtogether to form a long chain %polymer'.nC#2 8 C#2 – -%- C#2 – C#2 -'-n

ethene %monomer'%unsaturated compound' – polyethene polymer%saturated compound'It must be carry out in high temperature and pressure.

#ddition of hydrogen Hydrogenation"

6ddition reaction is atoms %or a group of atoms' are added to each carbonatom of a carbon-carbon multiple bond to a single bond.




3

water solvent'

Chemical

Properties

#l+anes

%)ubstitution reaction'

#l+enes

%6ddition reaction'

Heactivity +nreactive Heactive

Combustion Burn in air and produce yellow sooty

Name.

Burn in air and produce

yellow and sootier

Name compare to

al7anes.

Heaction with

bromine

solution

"o reaction. @ecolourise brown

bromine solution.

Heaction with

acidiGed

potassium

manganate%LII'

solution

"o reaction. @ecolourise purple

acidiGed potassium

manganate%LII'

solution.

2. $somerism

$somerism – phenomenon that two or more molecules are found to have the same

molecular formula but diRerent structural formulae.

$somerism in al+anes

;olecular formula "umber of isomers )tructure name

C#$ - %no isomer' ;ethane

C2#* - %no isomer' /thane




1:

C# - %no isomer' =ropane

C$#1: 2 Butane2-methylpropane

C(#12 =entane2-methylbutane2,2-

dimethylpropane

$somerism in al+enes

;olecular formula "umber of isomers )tructure name

C2#$ - %no isomer' /thene

C#* - %no isomer' =ropene

C$# But-1-eneBut-2-ene2-methylpropene

C(#1: ( =ent-1-ene=ent-2-ene2-methylbut-1-ene

-methylbut-1-ene

2-methylbut-2-ene

SPM Form 5 – Terminology and Concepts: Carbon Compounds Part 5"Non7Hydrocarbon – #lcohol1. 4eneral formula0 Cn#2n 1O#

Fhere n 8 1, 2, 9 %n 8 number of carbon'2. 6lcohols are non-hydrocarbons which contain carbon, hydrogen and o&ygenatoms. . <he functional group in alcohols is hydro&yl group, – O#.

"ame of alcohol ;olecular formula ofalcohol

;ethanol C#O#/thanol C2#(O#

=ropanol =ropan-1-ol

C#O#

Butanol Butan-1-ol C$#3O#

=entanol 8 =entan-1-ol

C(#11O#

#e&anol 8 #e&an-1-ol C*#1O#

#eptanol 8 #eptan-1-ol

C#1(O#

Octanol Octan-1-ol C#1O#"onanol "onan-1-ol C3#13O#

@ecanol @ecan-1-ol C1:#21O#

$. Physical properties of alcohol


;eltingpoint

Boilingpoint

=hysical stateat 2(?C




12

SPM Form 5 – Terminology and Concepts: Carbon Compounds

Non7Hydrocarbon – Carbo'ylic #cids

1. 4eneral formula0 Cn#2n1COO# Fhere n 8 :, 1, 2, 9 %n 8 number of carbon'

2. Carbo&ylic acids are non-hydrocarbons which contain carbon, hydrogen ando&ygen atoms.

. <he functional group in alcohols is carbo&yl group, – COO#.

"ame of carbo&ylicacids

;olecular formula ofalcohol

;ethanoicacid%5ormic acid'

#COO#

/thanoic acid%6ceticacid'

C#COO#

=ropanoic acid C2#(COO#

Butanoic acid C#CO#

$. Physical properties of carbo&ylic acid


Boiling point%?C'

;ethanoicacid%5ormic

acid'

#COO# 1:1

/thanoicacid%6cetic acid'

C#COO# 11

=ropanoic acid C2#(COO# 1$1

Butanoic acid C#CO# 1*$

Solubility in ,ater – generally in carbo&ylic acid %the less than fourcarbon atoms' are very soluble in water and ionise partially to form wea7 .

-ensity of carbo'ylic acid – density of carbo&ylic acid increases due tothe increases in thenumber of carbon atoms in a molecule.

*oiling points – all carbo&ylic acid in general have relatively high boiling

points than the corresponding al7anes. <his is due to the presence ofcarbo&yl group in carbo&ylic acid. Smell – carbo&ylic acid %> 1: carbon' are colourless and pungent smell.

Carbo&ylic acid %1: carbons' are wa&-li7e solids.

(. Preparation of carbo&ylic acid 4'idation of an alcohol

<he o&idation of ethanol is used to prepare ethanoic acid.C2#(O# 2POQ – C#COO# #2OCarried out by reNu&ingS ethanol with an o&idising agentPacidiGed potassium dichromate%LI' solution – orange colour turns to green

acidiGed potassium manganate%LII' solution – purple colour turns tocolourlessQ




1

S refux = upright Liebig condense to prevent the loss o a volatile liquidby vaporisation.

*. Chemical properties of carbo&ylic acid #cid properties

/thanoic acid is a wea7 monoprotic acid that ionises partially in water%produce a low concentration of hydrogen ions'.C#COO# >– C#COO- #

/thanoic acid turns moist blue litmus paper red. (eaction ,ith metals

/thanoic acid reacts with reactive metals %copper and metals below it inthe reactivity series cannot react with ethanoic acid'.%32 Na2 Mg2 #l2 9n2 Fe2 Sn2 Pb, Cu, #g, 6u'2C#COO# Tn – Tn%C#COO'2 #2

In this reaction, a colourless solution %Dinc ethanoate' is formed.2C#COO# ;g – ;g%C#COO'2 #2

In this reaction, a colourless solution %magnesium ethanoate' is formed. (eaction ,ith bases

acid neutralises al7alis %sodium hydro&ide'.C#COO# "aO# – C#COO"a #2OIn this reaction, a salt %sodium ethanoate' and water are formed.

(eaction ,ith carbonates/thanoic acid reacts with metal carbonates %calcium carbonate,magnesium carbonate, Dinc carbonate'.2C#COO# CaCO – Ca%C#COO'2 CO2 #2OIn this reaction, a salt %calcium ethanoate', carbon dio&ide and water areformed.

(eaction ,ith alcohols .steri&cation"/thanoic acid reacts with alcohol %ethanol, propanol, butanol'C#CO-4H H7OC$#3 – C#COOC$#3 #2O %Concentrated #2)O$ is acatalyst'In this reaction, an ester %colourless sweet-smelling liKuid' %butylethanoate' and water are formed.

. %ses of Carbo'ylic #cid Carbo&ylic acid %methanoic acid and ethanoic acid' is used to coagulate

late&. Linegar %dilute $U of ethanoic acid' is used as preservative and

Navouring. /thanoic acid is used to ma7e polyvinvyl acetate which is used to ma7e

plastics and emulsion paints. BenDoic acid is used as food preservative. Butanoic acid is used to produce ester %artiGcial Navouring'.




1$

SPM Form 5 – Terminology and Concepts: Carbon Compounds Part "Non7Hydrocarbon – .sters1. 4eneral formula0 Cn#2n1COOCm#2m1

Fhere n 8 :, 1, 2, 9 and m 8 1, 2, 9 %n and m 8 number of carbon'RCOORV where R and RV represented the same or diRerent al7yl groups.

2. /sters are non-hydrocarbons which contain carbon, hydrogen and o&ygenatoms.

. <he functional group in ester is carbo&ylate group, – COO -.Cn#2n1C44H Cm#2m14H – Cn#2n1C44Cm#2m1 #2O

5irst part0 ta7en from the alcohol %al7yl group' )econd part0 ta7en from the carbo&ylic acid %-oic to -oate'

"ame of ester ;olecular formulaof ester

=repared from

/thyl methanoate #COOC2#( /thanol ;ethanoic acid

;ethyl ethanoate C#COOC# ;ethanol /thanoic acid

=ropyl ethanoate C#COOC# =ropanol /thanoic acid

/thyl propanoate C2#(COOC2#( /thanol =ropanoic acid

$. Physical properties of ester

"ame Odour

-metylbutylacetate

Banana

/thyl butanoate =ineapple

Octyl ethanoate Orange

Isoamyl isovalerate 6pple

)imple esters are colourless liKuid and are found in fruits and Nowers. /sters have sweet pleasant smell. /sters are covalent compounds. /sters are insoluble in water but soluble in organic solvent. /sters are less dense than water. /sters are neutral and cannot conduct electricity. <he higher and more comple& esters have higher boiling points and less

volatile."atural sources0

Legetable oils %palm oil' and liKuids esters can be found in plants derivedfrom glycerol and fatty acids.

5ats are solid esters %mil7 fat' derived from glycerol and fatty acids.




1(

Fa&es %beewa&' are solid ester derived from long-chain fatty acids andlong-chain alcohols.

(. %ses of .sters =reparation of cosmetics and perfumes %esters are volatile and have sweet

smell'. )ynthetic esters used as food additives %artiGcial Navour'. "atural esters serves as storage reserve of energy in living things. In plant, wa& %esters' helps to prevent dehydration and attac7 of

microorganisms. /sters used as solvents for glue and varnishes. /sters used to ma7e plastics softer. /sters used to produce polyester %threads and synthetics fabrics' /sters used to produce soap and detergents.

SPM Form 5 – Terminology and Concepts: Carbon Compounds Part ; "

Non7Hydrocarbon – Fats

1. 5atrs are non-hydrocarbons which contain carbon, hydrogen and o&ygenatoms.2. 5ats %lipids triglycerides' are belonging to the group in ester.. "atural esters are formed from glycerol and fatty acids.

"ame of fat ;olecular formula of ester <ypes of fatty acids

Aauric acidS C#%C#2'1:COO# )aturated

=almitic acidS C#%C#2'1$COO# )aturated

)tearic acidS C#%C#2'1*COO# )aturated

Oleic o&ide SSC#%C#2'C#8C#%C#2'COO# +nsaturated

AinoleicacidSSS

C#%C#2'$C#8C#C#2C#8C#%C#2'COO#

+nsaturated

AinolenicacidSSS

C#C#2C#8C#C#2C#8C#C#2C#8C#%C#2'COO#

+nsaturated

* Saturated: ! single bonds** "nsaturated #$onounsaturated%: = double bonds

*** "nsaturated #polyunsaturated%: = double bonds$. 6nimal fats have higher percentage of saturated fatty acids than unsaturatedfatty acids.(. =lant oils have higher percentage of unsaturated fatty acids than saturatedfatty acids.

*. Physical properties of fats

)aturated +nsaturated

<ypes of fatty acids C-C single bonds C8C double bonds

Bonding single double

;elting point higher lower

)ources animals plants




1*

Cholesterol high low

)tate at roomtemperature

solid liKuid

5ats %animal' in general are solids at room temperature and acted as0 thermal insulator protective cushion to protect the vital organ provide energy and stored in body carry Litamin 6, @, /, ! %insoluble in water' /&ample0 butter, Gsh oil %liKuid in room temperature' 5ats %plant' are called oils. Oils are liKuids at room temperature. /&ample0 olive oil, peanut oil, palm oil and bran oil

. Chemical properties of fats +nsaturated fats can be converted into saturated fats

by hydrogenation %additional reaction' in 2::?C and $ atm in the presenceof nic7el catalyst.

/&ample0 production of margarine from sunNower oil of palm oil.

. .6ect of fats5atty food produce high energy but high consumption of fatty food will results0

obesity raise the level of cholesterol deposition will cause bloc7 the Now of blood which lead to stro7e and heart

attac7.

3. Palm oil It is e&tracted from fresh oil palm fruits. =alm oil – e&tracted from the pulp of the fruits.

)teps in e&traction of palm oil01. sterilising %oil palm fruit'2. stripping. digestion %crushing the hus7 and fruit and separate the oil by heating'$. sKueeDed out the oil(. e&traction %separate the oil from water'*. puriGcation the oil %palm oil is treated with phosphoric acid and then

steam is passed through to separate the acid'. vacuum

=alm 7ernel oil – e&tracted from the 7ernel or seed.)teps in e&traction of palm oil0

1. sterilising %oil palm fruit'2. stripping. crushing the hus7 and fruit$. e&tracting 7ernel oil(. puriGcation %purify the oil from 7ernel'

4oodness in palm oil0 higher proportion of unsaturated fats. easy to digest and absorb. rich in vitamin 6 %carotenoid' rich in vitamin / %tocophenols and tocotrienols' resist o&idation in high temperature.




1

SPM Form 5 – Terminology and Concepts: Carbon Compounds Part < –Final"Polymers1. =olymer – many small units %monomers' oining together to formed largemolecule.2. =olymer can be classiGed into two groups0

synthetic polymers man-made polymers %polytheneW =LC – polyvinylchlorideW artiGcial sil7W and polypropene'

natural polymers %natural rubberW starchW celluloseW and proteins'. "atural polymer0 Carbohydrates polysaccharides" %starch, glycogen andcellulose'

4eneral formula0 C&%#2O'y with the ratio of #0O 8 201 Carbohydrates have cyclic structure. ;onomer0 glucose %C*#12#*' Heaction to form polymer0 condensation reaction %- #2O'

$. "atural polymer0 Protein polypeptide" =rotein consists of carbon, hydrogen, o&ygen and nitrogen %some have

sulphur, phosphorus and other elements' ;onomer0 amino acids 6mino acids have two functional group which are carbo&yl group %-COO#'

and amino group %-"#2' Heaction to form polymer0 condensation reaction %- #2O'

(. "atural polymer0 Natural rubber /&tracted from the late& of rubber tree %&evea brasiliensis' which the tree

originates from BraDil. 6 molecule of rubber contains (::: isoprene units. ;onomer0 isoprene, C(# or 2-methylbuta-1,-diene. Heaction to form polymer0 additional polymerisation %one of the double

bond in isoprene becomes single bond'*. Structure of rubber molecule




1

Aate& is colloid %(U rubber particles and *(U water'. Hubber particle contains rubber molecules which are wrapped by a layer

of negatively-charged protein membrane. )ame charge of rubbermolecules repels each other. <his prevent rubber from coagulate.

. Coagulation process of late'

<he process for the coagulation of late& is summarised as01. 6cid %#' can neutralise the negatively-charged protein membrane./&ample of acid0 formic acid, methanoic acid, suphuric acid andhydrochloric acid.

2. <he rubber molecules will collide after the protein membrane is bro7en.. Hubber molecules %polymers' are set free$. Hubber molecules combine with one another %coagulation'.

. Natural coagulation process of late'5or the natural coagulation of late&0

1. Aate& is e&posed to air without adding acid %duration – overnight'.2. Coagulation process occurs in slower pace due to the bacteria

%microorganism' action which produce acid'

3. Pre/ent coagulation process of late' <he following are late& coagulation prevention method0

1. 6l7aline Basic solution is added to the late&. /&ample0 ammonia %"#'.2. =ositively-charged hydrogen ion # produced by bacteria can be

neutralised by negatively-charged hydro&ide ion O# - from ammoniasolution.

1:. Properties of natural rubber elastic cannot withstand heat %become stic7y and soft – above (:?CW decompose

– above 2::?CW hard and brittle – cooled' easily o&idised %present of C8C' insoluble in water %due to the long hydrocarbon chains' soluble in organic solvent %propanone, benDene, petrol etc.'

11. 1ulcanisation of rubberLulcanisation – process of hardening rubber and increases rubber elasticity byheating it withsulphur or sulphur compounds.Methods:

heating natural rubber with sulphur at 1$:?C using Dinc o&ide as catalystor

dipping natural rubber in a solution of disulphur dichloride %)2Cl2'

in methylbenDene.12. Properties of /ulcanisation of rubber

<he sulphur atoms are added to double bonds in the natural rubbermolecules to formdisulphide lin7ages %-C-)-)-C-' sulphur cross-lin7s between the long polymer chains. <herefore, vulcanised rubberis more elastics and stronger.

<his increases the molecular siDe and the intermolecular forces ofattraction between rubber molecules. <herefore, vulcanised rubber is moreresistant to heat %does not become soft and stic7y when hot'.

<his also reduces the number of carbon-carbon double bonds in rubbermolecules. <herefore, vulcanised rubber is more resistant to o&ygen,

oDone, sunlight and other chemicals.1. Comparison bet,een the properties of /ulcanised rubber andun/ulcanised rubber




13

=roperties Lulcanised rubber +nvulcanised rubber

@oublebonds

@ecreases %formation ofsulphur cross-lin7s'

;ore number of doublebonds

;elting point #igh %presence ofsulphur'

Aow

/lasticity ;ore elastic %sulphurcross-lin7s prevents thepolymer chain or rubberfrom slipping past.

Aess elastics

)trength andhardness

)trong and hard%depends on degree ofvulcanisation'

Fea7 and soft %polymerchain of rubber willbrea7 when rubber isover stretched.

Hesistant toheat

Hesistant to heat =oor resistant to heat

O&idation Hesistant to o&idation%reduction of number ofdouble bonds per rubbermolecule'

/asily o&idised byo&ygen, +L light%presence of manydouble bonds perrubber molecules'

1$. ( = - of rubber HHI; – Hubber Hesearch Institute of ;alaysia ;HB – ;alaysian Hubber Board Hubber <echnology Centre Larious local higher institutions of learning

spm chemistry form 5 chap 2

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