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59.8 PREPARATION AND USES OF POLYMERS

  1. Polythene or Polyethylene. This is addition polymer of ethene. Two types of polythenes namely; high density polythene and lo\; density polythene, are being produced these days using different conditions for polymerisation.

nCH2= CH2     -(CH2-CH2)-n

ethane                        polythene

Characteristics and uses. It is used in film wraps and bags for packaging, water pipes, coating of telephones, electric wires and cables.

2. Polypropylene. The monomer units are propylene molecules. It is generally manufactured by passing propylene through n-hexane (inert solvent) containing Ziegler-Natta catalyst (a mixture of triethyl aluminium and titanium chloride).

   CH3                                           CH3

|                           Al(C2H5)3         |

nCH = CH2                  →         -(CH-CH2-)n

Propylene                                              Polypropylene

Characteristics and uses. It is harder, stronger and lighter than polyethene. It is used in: packing of textile material and food, liners of bags, gramophone records, ropes, carpet fibres etc.

3.  Polystyrene or Styron. The monomer units are styrene molecules. It is prepared by free radical polymerisation of styrene in the presence of benzoyl peroxide.

(C6H5CO)2O

nCH = CH2                  →         -(CH-CH2-)n

|                                                              |

C6H5                                                       C6H5

Styrene                                                Polystyrene

Characteristics and uses. It is a white thermoplastic material which is transparent and flats on water. It is used for making toys, combs, model construction kits, ceiling tiles, packing for delicate articles and lining material for refrigerators and TV cabinets.

Polystyrene is solid under the name Styrofoam or Styron.

4. Teflon or Poly Tetrafluoro Ethylene (PTFE). The monomer unit is Tetrafluro-ethylene molecules. The prepared by heating tetrafluroethylene under pressure in the presence of ammonium peroxo-sulphate [(NH4)2S2O8].

(NH4)2S2O6

nCF2 = CF2             →         -(CF-CF2-)n

Heat, pressure

Tetrafluroethylene                              Teflon

Characteristics and uses. It is a very tough material and is resistant towards heat, action of acids or bases. It is a bad conductor of electricity. It is used in:

Coating utensils to make them non-sticking, making seals and gaskets which can withstand high pressures, insulations for high frequency electrical installations.

5. Poly Monochloro Trifluoro Ethylene (PCTFE). The monomer unit are chloro-trifluoro ethylene molecules. It is prepared by the polymerization of monochlorotrifluoro ethylene

nCIFC = CF2             →         -(CIFC-CF2-)n

Chlorotrifluoro ethylene                                PCTFE

The properties of PCTFE are similar to Teflon. However, this is relatively less resistance to heat and chemicals.

6. Poly Vinyl Chloride (PVC). The monomer units are vinyl chloride molecules. It is prepared by heating vinyl chloride in an inert solvent in the presence of dibenzoyl peroxide.

Dibenzoyl peroxide

nCH2 = CH             →         -(CH2-CH-)n

|                                                    |

Cl                                                   Cl

Vinyl chloride                                      PVC

Characteristics and uses. PVC is a hard horny material. However, it can be made to aquire any degree of pliability by the addition of a plasticizer. It is resistant to chemicals as well as heat. It is used for making:

Rain coats, hand bags, toys, hosepipes, gramophone records, electrical insulations and floor covering.

7. Neoprene. This is synthetic rubber which resembles natural rubber in its properties. It is obtained by polymerization of chloroprene (2-chloro-1, 3-butadiene) in the presence of potassium persulphate.

nCH2 = C             →         CH = CH2

|

Cl

Chloroprene

↓ K2S2O8

-(CH2 – C = CH – CH2-)n

|

Cl

Neoprene

Characteristics and uses. Neoprene is superior to natural rubber in its stability to aerial oxidation and also in its resistance to oils and other solvents. It is generally used for making.

Hoses, shoeheels, stoppers and belts.

8. Buna-S. It is a copolymer of 1-3-butadiee and styrene, It is obtained by the polymerization of butadiene and styrene in the ratio of 3:1 in the presence of sodium. It is also known as styrene butadiene rubber (SBR)

nCH2 = CH – CH = CH2 + nC6H5CH5 =CH2

Butadiene                     Styrene

Na, ↓ Heat

-(CH2 – CH = CH – CH2 – CH – CH2 -)n

|

C6H5

Buna-S

In buna-S, Bu stands for butadiene; na for sodium which is polymerizing agent and S stands for styrene.

Characteristics and uses. SBR has slightly less tensile strength than natural rubber. It is used in the manufacture of:

Automobile tyres, rubber soles, belts, hoses, etc.

9. Terelene. It is a polymer obtained by the condensation reaction between ethylene glycol and terephthalic acid.

Fig.59.7

Characteristics and uses. Terelene is resistant to the action of chemical and biological substances and also to abrasion. It has a low moisture absorbing power. As such it is widely used in making wash and wear fabrics. The polyester textile fibers made from the polymer are marketed under the trade name terelene or dacron.

It is used as ablend with cotton and wool in clothing. It is also used in seat belts and sails. The polymer is also used as mylar in the preparation offilms, magnetic recording tapes and for packing frozen food. Dacron (and teflon) tubes are good substitutes for human blood vessels in heart by-pass operations.

10.      Glyptal or Alkyd Resin. Glyptal is a general name of all polymers obtained by condensation of di-basic acids, and polyhydric alcohols. The simplest glyptal is poly (ethylene glycol phthalate) which is obtained by the condensation of ethylene glycol and phthalic acid.

Fig.59.8

Characteristics and uses. These are three dimensional cross-linked polymers. Poly (ethylene glycol phthalate) dissolves in suitable solvents and the solution on evaporation leaves a tough and non-flexible film. Thus, it is used in:

adherant paints, lacquers and building materials like asbestos and cement.

      11. Nylon-6,6. It is a polymer of adipic acid , (1, 6-hexanedioic acid) and hexamethylene diamine (1, 6-diarninohexane)

O             O

||              ||

n H2N-{CH2)6-NH2 + nHO C-{CH2)4-COH

Hexamethylene diamine                          Adipic acid

- 525 K ↓ Heat

H             H                 O

|                    |                        ||

-( N-{CH2)6-N-C-{CH2)4-C)- + 2nH2O

||

O

(Nylon-66)

Characteristics and uses. Nylon-66 (read as nylon-six-six) can be cast into a sheet or fibers by spinning devices. Nylon fibers have high tensile strength. They are tough. and resistant to abrasion. They are also somewhat elastic in nature. Nylon finds uses in:

making bristels and brushes, carpets and fabrics in textile industry, elastic hosiery in the form of crinkled nylon.

12.      Nylon 6,10. It is’ a polymer of hexamethylene diarnine (six carbon atoms) and sebacoyl chloride (ten carbon atoms)

O               O

||                     ||

nH2N(CH2)6-NH2 + nCI- C (CH2)8 – C – Cl

heat ↓

H O             O

|    ||                   ||

-(HN-(CH2)6-N-C-(CH2)8- C )n +2nHCI

Nylon 610

13.      Nylon-6 (or Perlon), It is obtained from the monomer caprolactum. Caprolactum is obtained from cyclohexane , according to the reaction sequence given below:

Fig.59.9

Caprolactum on heating with traces of water hydrolyses to 6-amino caproic acid which on continued heating undergoes self-condensation and polymerises to give nylon-6. 

Fig.59.10

Nylon-6 is used for the manufacture of tyre cords, fabrics and ropes.

14.      Phenol-Formaldehyde Resin (Bakelite). These are made by the reaction of phenol and formaldehyde in basic medium. The reaction involves of formation of methylene bridges in ortho, para or ortho as well as para position as shown in the following reactions.

Characteristics and uses. Bakelite is a cross-linked thermosetting polymer. Soft bakelites with low degree of polymerisation are used as bonding glue for laminated wooden planks, in the preparation of-varnishes and lacquers .

High degree of polymerisation leads to formation of hard bakelite which is used for making combs, fountain pen barrels, gramophone records, electrical goods, formica table tops and
many other products. Sulphonated bakelites are used as ion-exchange resins for softening of hard water.

The reaction starts with the initial formation of o-and / or p-hydroxymethylphenol derivatives, which further react with phenol to form compounds having rings joined to each other through – CH2 groups. The initial product could be a linear product – Novolac used in paints.

Fig.59.11

Novolac on heating with formaldehyde undergoes cross linking to form an infusible solid mass called bakelite.

Fig.59.1215.      Melamine Formaldehyde Resin. Melamine and formaldehyde copolymerise to give another polymer.

Characteristics and uses. Melamine polymer is quite hard and is used in making plastic crockery under the trade name melmac. Cups, plates and other articles made from melamine polymer do not break on being dropped.

Fig.59.1316.      Natural Rubber, Rubber is a natural polymer and possesses elastic properties. It is obtained from a rubber tree. When the bark of the tree is cut, a sticky white liquid, latex, oozes out. It is a suspension of rubber particles in water.

Natural rubber is a linear polymer of 2-methyl-l, 3- butadiene (isoprene). It is also called as cis-l,4-poly isoprere. On an average it contains 5000 isoprene units. All the double bonds in natural rubber are Cis. Rubber is a waterproof material.

Fig.59.14

The cis-poly isoprene molecule consists of various chains held by weak van der Waals interactions and has a coiled structure. Thus it can be stretched like a spring and exhibits elastic properties. Gutta-percha (getah means gum and percha means tree) is a naturally occurring isomer of rubber in which all the double bonds are trans. Like rubber, gutta percha is exuded by certain trees. It is harder and more brittle than rubber

SYNTHETIC RUBBER

To meet human needs, scientists have started preparing synthetic rubbers. Besides having similar properties as natural rubbers they are tougher, more flexible and more durable than natural rubber. They are capable of getting stretched to twice its length. However, it returns to its original shape and size as soon as the external stretching force is released. Synthetic rubbers have been made by the polymerisation of dienes other than isoprene. The polymerisation is carried
out in the presence of Zeigler-Natta catalyst. For example, Polymerisation of I, 3-butadiene

Fig.59.15

PREPARATION OF SYNTHETIC RUBBERS

 1. Neoprene or polychloroprene is formed by the free radical polymerisation of chloroprene.

Fig.59.16

It has superior resistance to vegetable and mineral oils. It is used for manufacturing of conveyer belts, gaskets and hoses.

 BIODEGRADABLE POLYMERS

These are polymers that can be broken into small segments by enzyme-catalysed reactions. The required enzymes are produced by microorganism. It is a known fact that the carbon-carbon bonds of chain growth polymers are inert to enzyme-catalysed reactions, and .hence they are non-biodegradable. To make such polymers biodegradable we have to insert certain bonds in the chains so that these can be easily broken by the enzymes. Now when. such polymers are buried as waste, microorganisms present in the ground can degrade the polymer.

One of the best methods of making a polymer biodegradable is by inserting hydrolysable ester group into the polymer.

For example if acetal is added to an alkene undergoing radical polymerisation, ester group will be inserted into the polymer.

Fig.59.17

The weak links in the polymer are susceptible to enzyme catalysed hydrolysis.

Aliphatic polyesters are one of the important class of biodegradable polymers. Some other examples of biodegradable polymers are described below:

i.            PHBV (Poly-hydroxybutrate-co-β-hydroxy valerate). It is a copolymer of 3-hydroxy butyric acid and 3~hydroxypen1anoic acid.

 

 

 

 

 

 

PHBV is used in orthopaedic devices and controlled drug release. The drug put in PHBV capsule is released after this polymer is degraded by enzymatic action. It can also be degraded by bacterial action.

i.            Poly glycolic acid and. poly lactic acid. These are also biodegradable polymers and are used for post operative stiches. These are bioabsorbable structures.

ii.            Nylon-2-Nylon-6. It is an alternating polyamide copolymer of glycine (H2N-CH2-COOH) and amino caproic acid (H2N-(CH2)5COOH) and is biodegradable.

 

 

 

 

DISADVANTAGES OF POLYMERS

Environmental Pollution by Plastics

Plastic materials are used to make a large number of domestic and industrial materials. Most of the plastics are strong and not easily destroyed by bacteria when disposed of after use. They are non-biodegradable. When disposed of on the surface of the ground, inside the ground or elsewhere, they do not decay and remain there for about one hundred years.

For example, they may collect together in drains and block the drainage, thus creating sewage problems. The drains may have to be dugout to remove the non-biodegradable plastic materials such as polythene.

Plastics can be. burnt at refuse dumps, but the products of burning can be hazardous. Burning of PVC plastics, which contain chlorine, produces pungent smelling hydrogen chloride gas and chlorine gas which are poisonous to humans and plants.

Pollution by plastics may be reduced by reduction in plastic use, more use of biodegradable plastics, incineration and recycling.

SUMMARY

  • Polymer: A substance with giant molecules having high molecular mass.
  • Polymerisation: The process in which large number of small molecules combine to form a giant molecule or a macromolecule. The small molecules are called monomers.
  • Homopolymer: A polymer formed by combination of only one type of monomers.
  • Copolymer: A polymer formed by combination of two or more different types of monomers.
  • Addition Polymers: The polymers formed by combination of large number of monomers without the elimination of any smaller molecules.
  • Cross-linked Polymers: Monomers cross-link to form a network. These are hard and rigid.
  • Condensation Polymers: During formation of such polymers, elimination of smaller molecules such as H2O, NH3, etc., takes place.
  • Polythene: It is a polymer of ethene.
  • Poly vinylchloride: It is formed by the polymerisation of viny1chloride (CH2 = CH -Cl).
  • Phenol-methanal plastics: It is commercially known as Bakelite.
  • Elastomers: In this type of polymers, the polymeric chains are held by weak intermolecular forces. For example, rubber.
  • Fibres: These are thread like polymers having hydrogen bonds as intermolecular forces between different polymeric chains. For examples, cotton, nylon-66.
  • Thermoplastics: These are the polymers that soften on heating and can be. moulded into any shape. Intermolecular forces in them are intermediate between fibres and elastomers.
  • Thermosetting Polymers: These polymers are very hard, infusible and have extensive .cross links. For example, bakelite.
  • Plastic: A polymer which is readily deformable and can be moulded into any shape.
  • Vulcanisation: Heating of natural rubber with sulphur to make it strong.
  • Resilency Property: The property of returning to the original shape after distortion within elastic limit.
  • Isoprene: 2-Methyl-l, 3-butadierre. Monomer of natural rubber.
  • Plasticizer: A substance that when added to a thermoplastic improves its workability.
  • Caprolactum: Starting material for Nylon-6, a synthetic polyamide fibre.
  • Wool: A natural polyamide fibre.
  • Poly Urethane: It is formed by reaction of. di-isocyanate with a polyester having hydroxy groups on ends. These are used as leather substitute.

 

EVALUATE YOURSELF

I. Objective Type Questions

Select the most appropriate choice from, the options given as (a), (b), (c) and (d) after each question:

1.      Polymers are

a)      micromolecules

b)      macromolecules

c)      sub-micromolecules

d)     none of these.

2.      Bakelite is

a)      addition polymer

b)      elastomer

c)      thermoplastic

d)     thermosetting

3.      The S in Buna-S refers to

a)      sodium

b)      sulphur

c)      styrene

d)     just a trade name

4.      The repeating units of PTFE am

a)      Cl2CH-CH3

b)      F2C = CF2

c)      F3C-CF3

d)     FCIC = CF2

5.      The inter-particle forces between linear chains in Nylon-66 are

a)      H-bonds

b)      covalent bonds

c)      ionic bonds

d)     unpredictable.

6.      Nylon-66 is a polyamide of

a)      viny1chloride and formaldehyde

b)      adipic acid and methyl amine

c)      adipic acid and hexamethylene diamine

d)     formaldehyde and malamine.

7.      Which of the following is not a condensation polymer?

a)      Glyptal

b)      Nylon-66

c)      Dacron

d)     PTFE.

8.      Which of the following is a condensation polymer?

a)      Polystyrene

b)      Neoprene

c)      PAN

d)     Poly (ethylene glycol phthalate).

9.      The monomer of PVC is

a)      ethylene

b)      tetrafluoroethylene

c)      chloroethene

d)     none of the above.

10.  Which of the following polymers is, a copolymer?

a)      Polypropylene

b)      Nylon-66

c)      PVC

d)     Teflon

11.  Which of the following polymers is a homopolymer?

a)      Bakelite

b)      Nylon-66

c)      Terylene

d)     Neoprene.

12.  Which of the following types of polymers has the strongest       interparticle forces?

a)      Elastomers

b)      Thermoplastics

c)      Fibers

d)     Thermosetting polymers.

13.  Bakelite is obtained from phenol by reacting with

a)      ethanol

b)      methanal

c)      vinyl chloride

d)     ethylene glycol.

14.  Polymer used. in, bullet proof glass is

a)      PMMA

b)      lexan

c)      nomex

d)     kevlar

15.  Nylon-6 is made from

a)      1, 3-Butadiene

b)      chloroprene

c)      adipic acid

d)     caprolactam.

16.  F2C = CF2 is a monomer of

a)      Teflon

b)      glyptal

c)      nylon-6

d)     buna-5.

17.  Soft drinks and baby feeding bottles are generally made up of

a)      polyester

b)      polyurethane

c)      poly urea

d)     polyamide

e)      polystyrene.

18.  Nylon threads are made of

a)      polyvinyl polymer

b)      polyester polymer

c)      polyamide polymer

d)     polyethylene polymer.

19.  (-NH(CH2)6-NHCO(CH2)4CO-)n is a

a)      homopolymer

b)      copolymer

c)      addition polymer

d)     thermosetting polymer.

20.  Which is not a polymer?

a)      Sucrose

b)      enzyme

c)      Starch

d)     teflon

 

II. Fill in the Blanks

21.  Complete the following sentences by supplying the appropriate words:

i.            On the basis of their origin polymers are classified as …… and …… polymers.

ii.            The three natural fibres are ……

iii.            Natural rubber is a polymer of ……

iv.            Phenol formaldehyde resin is commonly called ……

v.            Nylon-6 is a polymer of ……

vi.            The monomer units of PAN is ……

vii.            The monomer units of PMMA is ……

viii.            In Buna-S, S stands for …….

ix.            Lucite is a polymer of ……

x.            The starting material of PCTFE is ……

 

III. Discussion Questions

22.  Explain the following terms with examples:

a)      Polyester

b)      Polyamide

c)      Natural polymers

d)     Synthetic polymers.

23.  Give the classification of polymers:

a)      On the basis of their mode of synthesis; and

b)      On the basis of nature of forces between the macromolecules.

Give suitable example in each case.

24.  What is a polyamide? How is Nylon-6 synthesised?

25.  How does vulcanised rubber differ from natural rubber?

26.  Define the terms: Thermoplastic polymers, Thermosetting polymers, Fibers and Elastomers.

27.  Give the starting material of each of the following:

a)      PMMA

b)      PCTFE

c)      PAN

d)     PVC

28.  What is the difference between nylon-6 and nylon-66?

29.  Give the structures of monomers of bakelite. How is it formed? To which class, thermosetting or thermoplastic does it belong? Give reasons.

30.  Write the names and structures of the monomer of each of the following. Give one use of each of the polymers.

a)      Terelene

b)      Neoprene

c)      Natural rubber

d)     Lucite.

31.  What do you understand by linear, branched chain and cross-linked polymers?

32.  Given examples of polymers belonging to following categories. Give their structures:

a)      Polyamide

b)      Polyhaloolefins

c)      Polyolefins

d)     Polyesters

e)      Polyacrylates.

33.  Arrange the following polymers in increasing order of their intermolecular forces. Also classify them as addition and condensation polymers. Nylon-6, Neoprene, PVC.

34.  Mention which of the following are addition polymers?

a)      Terylene

b)      Nylon-66

c)      Neoprene

d)     Teflon.

35.  Write the information asked for the following polymers:

a)      Bakelite: materials required for preparation

b)      PVC: monomer unit

c)      Synthetic rubber: monomer unit.

36.  Give one method of synthesis of each of the following:

a)      Buna-S

b)      Teflon

c)      Nylon-66.

37.  What is the difference between homopolymer and co-polymer? Give one example.

38.  Define any two plasticizers.

39.  How are polymers classified into different categories on the basis of intermolecular forces? Give one example of a polymer of each of these categories.

40.  How do double bonds in rubber molecule influence their structure and reactivity?

41.  Differentiate between addition and condensation polymers based on mode of polymerisation. Give one example of each type.

 

Answers

I. Objective Type Questions

1.      (b)

2.      (d)

3.      (c)

4.      (b)

5.      (a)

6.      (c)

7.      (d)

8.      (d)

9.      (c)

10.  (b)

11.  (d)

12.  (d)

13.  (b)

14.  (b)

15.  (d)

16.  (a)

17.  (e)

18.  (c)

19.  (b)

20.  (a)

 

II. Fill in the blanks

21.  (i) natural, synthetic

(ii) wool, cotton and silk

(iii) isoprene

(iv) bakelite

(v) caprolactum

(vi) acrylonitrile

(vii) methylmethacrylate

(viii) sulphar
(ix) methyl methacrylate

(x) chlorotrifluroethylene

APPENDIX 1

IUPAC NOMENCLATURE FOR SOME INORGANIC SUBSTANCES AS ADOPTED BY WAEC

EXAMPLES OF RECOMMENDED NAMES ‘BINARY COMPOUNDS

Common name

Formula

WAEC adopted IUPAC name

nitrous oxide N2O nitrogen(I) oxide or dinitrogen monoxide
nitric oxide NO nitrogen(lI) oxide or nitrogen monoxide
nitrogen dioxide NO2 nitrogen(IV) oxide or nitrogen dioxide .
nitrogen tetraoxide N2O4 dinitrogen tetraoxide*
nitrogen pentoxide N2O5 nitrogen(V) oxide
phosphorus decaoxide P4O10 tetraphosphorus decaoxide**
sodium hydride NaH sodium hydride
triplumbic tetraoxide Pb3O4 trilead tetraoxide***
lead monoxide PbO lead(II) oxide
lead dioxide PbO2 lead(IV) oxide
hydrogen fluoride HF hydrogen fluoride
water H2O water

* dinitrogen tetraoxide is so called to distinguish it from nitrogen(IV) oxide of which it is the dimer,
** Where P2O5 is mentioned it should be referred to as phosphorus(V) oxide.

*** This compound behaves as though the formula is 2PbO.PbO2 and so it is sometimes called dilead(II) lead(IV) oxide.

 

Common name

Formula

WAEC adopted IUPAC name

hydrogen sulphide
ammonia
calcium acetylide/carbide
potassium oxide
potassium peroxide
potassium superoxide
phosphorus trichloride.
phosphorus pentachloride
carbon dioxide
carbon monoxide
sulphur dioxide
sulphur trioxide
manganous oxide
manganic oxide
manganese dioxide
trimanganic tetraoxide
ferrous oxide
ferric oxide
aluminium carbide
hydrogen chloride
hydrated hydrogen ion
borohydride ion
ammoniacal cuprous ion
zinc ammonium ion
silver ammonium ion
aluminium hydride ion
ammonium ion
ferrocyanide
ferricyanide
cuprammonium ion
aluminate ion

H2S
NH3
CaC2
K2O
K2O2
KO2
PCl3
PCl5
CO2
CO
SO2
SO3
MnO
Mn2O3
MnO2
Mn3O4
FeO
Fe2O3
Al4C3
HCI
H3O+
BH4-
Cu(NH3)2+
Zn(NH3)42+
Ag(NH3)2+
AlH4
NH4+
Fe(CN)64-
Fe(CN)63-
Cu(NH3)42+
*Al(OH)4-Al(H2O)2(OH)4-

hydrogen sulphide
ammonia
calcium dicarbide
potassium oxide
potassium peroxide
potassium superoxide
phosphorus (III) chloride
phosphorus(V) chloride
carbon (IV) oxide or carbon dioxide
carbon (II) oxide or carbon monoxide
sulphur (IV)oxide or sulphur dioxide
sulphur (VI) oxide or sulphur trioxide .
manganese(II) oxide
manganese(III) oxide
manganese(N) oxide or manganese dioxide
trimanganese tetraoxide
iron(II) oxide
iron(III) oxide
aluminium carbide
hydrogen chloride
oxonium ion or hydronium ion or hydroxonium ion
tetrahydridobonite(III) ion
diamminecopperfl) ion
tetraarnrninezinc(II) ion
diamrninesilver(I) ion
tetrahydridoalurninate(III) ion
ammonium ion
hexacyanoferrate (II) ion
hexacyanoferrate(III) ion
tetraarninecopper (II) ion
tetrahydroxoalurninate(III) ion tetrahydroxodiaquaaluminate (III)

* Where AlO2-is met, it should be called dioxoaluminate(III) ion,

OXOANIONS

Common name

Formula

WAEC adopted IUPAC name

hydrogen carbonate ion
hypochlorite ion
perchlorate ion

HCO32-
ClO-
Cl04-

Hydrogentrioxocarbonate (N) ion
oxochlorate (I) ion
tetraoxochlorate(VII) ion

Common name

Formula

WAEC adopted IUPAC name

permanganate ion
manganate ion
dichromate ion
chromate ion
thiosulphate ion

 

tetrathionateion

persulphate ion
sulphate ion
sulphite ion
nitrate ion
nitrite ion
carbonate ion

MnO4-
MnO42-
Cr2O72-
Cr2O42-
S2O32-

 

S4O62-

S2O82-
SO42-
SO32-
NO3-
NO2-
CO32-`

tetraoxomanganate(VII) ion
tetraoxomanganate (VI) ion
hexaoxo-µ-oxo-dichromatet (VI) ion
tetraoxochromate (VI) ion
thiosulphate ion or trioxosulphur-sulphate(VI) ion or trioxothiosulphate(VI) ion,

tetrathionate or tetraoxodithioperoxo disulphate (VI) ion or tetraoxodisulphur-µ-peroxodisulphate(VI) ion
persulphate or hexaoxo-µ-peroxodisulphatet (VI) ion
tetraoxosulphate(VI) ion
trioxosulphate(IV) ion
trioxonitrate(V) ion
dioxonitrate(III) ion
trioxocarbonate (IV) ion

ACIDS

Common name

Formula

WAEC adopted IUPAC name

nitric acid
nitrous acid
hydrochloric acid
sulphuric acid
sulphurous acid
carbonic acid

HNO3
HNO2
HCL(aq)
H2SO4
H2SO3
H2CO3

trioxonitrate (V) acid
dioxonitrate (III) acid
hydrochloric acid
tetraoxosulphate (VI) acid
tricxosulphate (IV) acid
trioxocarbonate (IV) acid

BASES

Common name

Formula

WAEC adopted IUPAC name

ferric hydroxide
ammonium hydroxide
sodium hydroxide
ferrous hydroxide

Fe(OH)3
NH3(aq)
NaOH
Fe(OH)2

iron(III) hydroxide
aqueous ammonia/ammonia solution
sodium hydroxide
iron(II) hydroxide

SALTS

Common name

Formula

WAEC adopted IUPAC name

sodium sulphate
sodium carbonate
sodium nitrate

Na2SO4
Na2CO3
NaNO3

sodium tetraoxosulphate (VI)
sodium trioxocarbonate (IV)
sodium trioxonitrate (V)

Common name

Formula

WAEC adopted IUPAC name

cupric sulphate
sodium chloride

CuSO4
NaCl

copper (II) tetraoxosulphate(VI)
sodium chloride

Hydrated’ salts

sodium carbonate decahydrate
ferrous sulphate heptahydrate

Na2CO3,10H2O FeSO4·7H2O

sodium trioxocarbonate (IV) decahydrate
iron(II) tetraoxosulphate(VI) heptahydrate

Double salts

potash alum

ferrous ammonium sulphate

KAl(SO4)212H2O

Fe(NH4)2(SO4)6H2O

aluminium potassium bisulphate (tetraoxosuiphate(VI))
dodecahydrate
diammonium iron(II) bisulphate (tetraoxosuiphate(VI))
hexahydrate

Basic salts

bismuth oxychloride
basic lead carbonate

BiOCl
Pb2CO3(OH)2

bismuth (III) chloride oxide
dilead(II) trioxocarbonate(IV) dihydroxide

APPENDIX 2
NOMENCLATURE OF ORGANIC COMPOUND
The term nomenclature means the system of naming of organic compounds. In the early stages of development of organic chemistry, the organic compounds were named after the source from which they were prepared. For example, the name acetic acid was derived from acetum (Latin: acetum means vinegar). Similarly, the name formic acid was derived from formicus (means red ants) because the compound was obtained by the distillation of red ants. Methyl alcohol was
named wood-spirit as it was obtained from the destructive distillation of wood. These names of organic compounds are called common names or trivial names. The common names were assigned to the organic compounds at the whim and fancy of the discoverer and there was no systematic basis. In many cases, even the same compound was given more than one names. For example, methane was named as marsh gas as well as damp fire.
Towards the end of nineteenth century/the number of organic compounds known was so large that it became difficult to remember their individual names. In order to rationalise the system of nomenclature, a comprehensive system of nomenclature known as Geneva system was developed. There was further improvement in Geneva system was developed. International Union of Chemists (IUC System) .
The IUC system has been further revised by the International Union of Pure and Applied Chemistry in the light of practical difficulties. This revised system of nomenclature has been accepted all over the world and is abbreviated as IUPAC system of nomenclature. The rules discussed here are based on the recommendations made by IUPAC in 1979 and 1993.
NOMENCLATURE OF ALIPHATIC HYDROCARBONS
A. Straight Chain Hydrocarbons
The name of a straight chain aliphatic hydrocarbon, in general, may be divided into two parts; word root and suffix. Word root designates the number of carbon atoms in the chain. For chains containing one to four carbon atoms, the special word roots are used and for chains of five or more carbon atoms Greek number roots are used. IUPAC word roots for a few carbon chains are given in Table 1. The general word root for any carbon chain is alk-.

Table 1. Word Roots for Carbon Chain Length

Chain Length

Word Root

Chain Length

Word Root

C1
C2
C3
C4
C5

Meth-
Eth-
Prop-
But-
Pent-

C6
C7
C8
C9
C10

Hex-
Hept-
Oct-
Non-
Dec-

In order to derive the IUPAC name, a suffix is added to the word root to indicate saturation or unsaturation in the molecule. The-suffixes, thus used are called primary StifiIXes; The primary suffixes as given in Table 2.
Table 2. Primary suffixes

Table 1. Word Roots for Carbon Chain Length

Class of Compound

Primary Suffix

General Name

Saturated
Unsaturated (>C = C<)
Unsaturated (-C = C-)

-ane
-ene
-yne

Alkane
Alkene
Alkyne

Table 3. Names of Alkanes

Molecular Formula

IUPAC Name

  1. CH4
  2. CH3CH3
  3. CH3CH2CH3
  4. CH3CH2CH2CH3
  5. CH3CH2CH2CH2CH3
  6. CH3CH2CH2CH2CH2CH3
  7. CH3CH2CH2CH2CH2CH2CH3
  8. CH3CH2CH2CH2CH2CH2CH2CH3
  9. CH3CH2CH2CH2CH2CH2CH2CH2CH3
  10. CH3CH2CH2CH2CH2CH2CH2CH2CH2CH3

Methane
Ethane
Propane
Butane
Pentane
Hexane
Heptane
Octane
Nonane
Decane

NAMES OF SOME HIGHER MEMBERS OF ALKANE SERIES

C11H24
C12H26
C13H28
C14H30
C15H32

Undecane
Dodecane
Tridecane
Tetradecane
Pentadecane

C16H34
C17H36
C18H38
C19H40
C20H42

Hexadecane
Heptadecane
Octadecane
Nonadecane
Isosane

B. Branched Chain Hydrocarbons
In branched chain compounds all the carbon atoms are not present in straight chain; Some of the carbon atoms in these compounds are present as side chains. These carbon atoms in side chains constitute alkyl groups or alkyl radicals and are expressed as prefixes in the IUPAC name. An alkyl group is obtained from an alkane by removal of a hydrogen. Since general formula of alkanes is CnH2n+2,the general formula for alkyl group is CnH2n+1An alkyl group is generally represented by R-. The alkyl radical is named by replacing suffix ane from the name of the corresponding alkane by yl. The position of the hydrogen atom removed is indicated by giving it the lowest possible number from the chain end. The names and formulae of some common alkyl groups are given in Table 4.
A branched chain hydrocarbons is named using the following general rules:
Rule 1. Longest Chain Rule
Select the longest continuous chain of carbon atoms as the parent chain. If some carbon-carbon multiple bond is present, the parent chain mustcontain the carbon atoms involved in it. The number of carbon atoms in the parent chain determines the word root. The carbon atoms which are not included in the parent chain are considered as alkyl substituents and determine the prefixes.

CH3-CH2-CH2-CH2-CH-CH3
                                 |
                                CH2 – CH2
Prefix:           methyl
Word root:    hept
P.suffix:        ane

          CH3
          |
CH3–CH–C–CH2–CH3
                ||
               CH2
Prefixes:      ethyl; methyl
Word root:   but
p. suffix:      ene

If two equally long chains are possible, the chain with maximum number of side chains is selected as parent chain. For example,
                         
                          CH3
                          |
CH3–CH2–CH–CH–CH3
                  |
                 CH–CH3
                 |
                CH3
                Correct
Prefixes:      ethyl; dimethyl
Word root:   pent
p. suffix:      ane

                          CH3
                          |
CH3–CH2–CH–CH–CH3
                  |
                 CH–CH3
                 |
                CH3
               Wrong

Rule 2. Lowest Number or Lowest Sum Rule
The selected parent chain is numbered using Arabic numerals and the positions of the alkyl groups are indicated by the number of the carbon atom to which the alkyl group is attached. The numbering is done in such a way that the substituted carbon atoms have the lowest possible numbers.

Table 4. Some Common Alkyl Groups

Parent Alkane

Formula (R-H)

Alkyl Group R-

Name

Methane
Ethane
Propane

CH4
CH3CH3
CH3CH2CH3

CH3 – 
CH3CH2 –
CH3CH2CH2–
CH3CHCH3

Methyl
Ethyl
1-Propyl (n-Propyl)
2-Propyl (iso-Propyl)

When series of locants containing the same number of terms are compared term by term, that series is lowest which contains the lowest number on the occasion of first difference. Some examples are given to illustrate the rule.

1CH3 – 2CH – 3CH2 – 4CH3
               |
              CH3
       2-Methylbutane
           (Correct)

4CH3 – 3CH – 2CH2 – 1CH3
              |
             CH3
         3-Methylbutane
             (Wrong)

             CH3              CH3
              |                    |
1CH3 – 2C – 3CH2 – 4CH – 5CH3
              |
             CH3
         2,2,4-Trimethylpentane
                  (Correct)

             CH3              CH3
              |                    |
5CH3 – 4C – 3CH2 – 2CH – 1CH3
              |
            CH3
        2,4,4 – Trimethylpentane
                   (Wrong)

1          2       3       4         5       6
CH3 – CH – CH – CH2 – CH – CH3
           |         |                   |
          CH3   CH3             CH3
     2,3,5-Trimethylhexane
              (Correct)

6          5       4       3         2        1
CH3 – CH – CH – CH2 – CH – CH3
            |        |                    |
          CH3   CH3              CH3
       2,4,5-Trimethylhexane
                (Wrong)

CH3             CH3
|                    |
9         8        7       6         5         4         3        2         1
CH2 – CH – CH – CH2 – CH2 – CH2 – CH2 – CH – CH3
           |                                                              |
          CH3                                                        CH3
                    2,7,8-Trimethyldecane

2,7,8-Trimethyldecane is the correct name of the above compound, 3,4,9-Trimethyldecane is wrong name although it has the lowest sum of numbers. The first name is correct because 2 is lower than 3 when we compare the locants in the two names, term by term.
In case of unsaturated hydrocarbons, the carbon atoms involved in the multiple bond should get the lowest possible number. For example,

4CH3 – 3CH – 2CH = 1CH2
              |
             CH3
           3-Methylbut-1-ene
                  (Correct)

1CH3 – 2CH – 3CH = 4CH2
              |
             CH3
        2-Methylbut-3-ene
               (Wrong)

The name of the compound, in general, is written in the following sequence:
(Position of substituents) – (Prefixes) (Word root)
(p. suffix)
The above sequence is illustrated in the following examples

                           CH3
                            |
1CH3 – 2CH2 – 3CH – 4CH2 – 5CH3

Here, prefix is methyl;themethyl group is at carbon number 3 in the parent chain. Word root is pent and primary suffix is ane. Hence, the name is: 3-Methylpentane



                CH3
                 |
4CH3 – 3CH – 2C = 1CH

 

Here, prefix is methyl; word root is but; primary suffix is yne. Methyl group is at the carbon number 3 and the triple bond is carbon number 1. Thus, the name is:
3-Methylbut-1-yne
If the compound contains more than one similar alky groups, their positions are indicated separately the name of the substituent is not repeated but an appropriate numeric, prefix, di, tri, etc., is attached to the name of the substitue the positions of the substituents are separated by commas.

               CH3      CH3
               |          |
1CH3 – 2CH – 3CH – 4CH2 – 5CH3
         2,3-Dimethylpentane

                          CH3
                           |         
5CH3 – 4CH2 – 3C – 2CH – 1CH3
                           |        |    
                          CH3     CH3
         2,3,3-Trimethylpentane

Rule 4. Alphabetical Arrangement of Prefixes
If there are different alkyl substituents present in the compound, their names are written in the alphabetical order. However, the numerical prefixes such as di, tri, etc., are not considered for the alphabetical order. For example,
Naming different alkyl substituents at the equivalent positions. If two different alkyl groups are located at the equivalent positions, then numbering of the chain is done in such a way that the alkyl group which comes first in alphabetic order gets the lower position. For example, if ethyl and methyl groups are present at equivalent positions, then carbon bearing ethyl group should get the lower number as illustrated in the following example:


                           C2H5     CH3
                            |          |
1CH3 – 2CH2 – 3CH – 4CH – 5CH2 – 6CH3
         3-Ethyl-4-methylhexane

In the light of the above rules, let us write the IUPAC names of some aliphatic hydrocarbons.

                          C2H5
                           |         
6CH3 – 5CH2 – 4C – 3CH2 – 2CH – 1CH3
                           |                    |    
                          CH3                        CH3
         4-Ethyl-2,4-dimethylhexane

             CH3
              |         
1CH3 – 2C – 3CH3
               |    
              CH3
2,2-Dimethylpropane

CH3 – 3CH – 4CH3
            |         
CH3 – C – CH2
            2      1
2,3-Dimethylbut-1-ene

NOMENCLATURE OF COMPOUNDS CONTAINING FUNCTIONAL GROUPS
In case some functional group (other than C = C
C = C) is present in molecule, it is indicated by adding secondary suffix after the primary suffix. The terminal ‘e’ of the primary suffix is generally removed before adding secondary suffix. The terminal ‘e’ of the primary suffix is removed if it is followed by a suffix beginning with ‘a’, ‘i’, ‘o’, ‘u’ or ‘y’.
Some functional groups (such as -OR) are indicated by the prefixes. The various classes of organic compounds, their functional groups, the secondary suffixes (or prefixes used to indicate them along with their general IUPAC names, are given in Table 5. It may be mentioned here that the  groups -NO2, -OR, -F, -Cl, -Br and -I are considered substituents and are indicated by the prefixes whereas the groups -CHO,-CO-, -COOH, -COCl, -CONH2, -COOR, -NH2, -CN and -OH, are considered as functional groups and are indicated by suffixes.
Name of an organic compound containing functional group is derived through the following steps:
Step l. Select the longest continuous chain of the carbon atoms as parent chain. The selected chain must include the carbon atoms involved in the functional groups like -COOH, -CHO, -CN etc., or those which carry the functional groups like –OH, -NH2, -Cl, -NO2 etc. The number of carbon atoms in parent chain decides the word root
Step 2. In order to decide the primary suffix, the presence of carbon-carbon multiple bond in chain is observed.
Step 3. The functional group present is identified: enables the selection of appropriate secondary suffix or prefix.
Step 4. The carbon atoms of the parent chain are numbered in such a way so that the carbon atom of the functional group gets the lowest possible number. In case the functional group does not have the carbon atom, then the carbon atom of the parent chain attached to the functional group should get the lowest possible number.
Step 5. The name of the compound is then arrived at by arranging prefixes and suffixes along with their positions as follows:
Prefixes – word root – primary suffix – secondary suffix
Let us now apply various rules to write the names of some organic compounds.

SOLVED EXAMPLES

Example 1. Give IUPAC name of the following compound:
Solution. 1. The longest chain containing functional group is of six carbon atoms. Therefore, the word root is hex.
CH3 – CH2 – CH – CH2 – CH – CH3
           |                              |
          CH2OH                  CH2-CH3

2. There is no multiple bond in it. Hence, the primary suffix is ane.
3. The functional group is -OH. Hence, secondary suffix is-ol.
4. The chain is numbered as shown. The functional group -OH is on carbon 1. Moreover, there is a methyl group on carbon 4 and ethyl group on carbon 2.
5. The IUPAC name is, therefore, 2-Ethyl-4-methylhexan-1-ol.

Example 2. Give the IUPAC name of the following compound:
CH3-CH2-CH-CH = CH-CH2-CHO
                 |
                CH3

Solution.   7       6     5     4     3      2      1
                 CH3-CH2-CH-CH=CH-CH2-CHO
                                  |
                                 CH3

1. The longest chain containing functional group is of seven carbon atoms. Therefore, word root is hept.
2. As C = C double bond is present in the molecule. Thus, the primary suffix is ene.
3. The secondary suffix is al because of presence of -CHO group.
4. The chain is numbered as shown so that carbon atom of -CHO group gets number 1. The methyl group is present on carbon 5 while position of double bond is 3. Thus, IUPAC name is
5- Methylhept-3-en-1-al,

MORE EXAMPLES OF COMPOUNDS CONTAINING ONE FUNCTIONAL GROUP
                                   O
                                   ||
4CH2 – 3CH = 2CH – 1C – OH
          But-en-1-oic acid

                         OCH3
                         |
4CH3 – 3CH = 2C – 1CH3
   2-Methooxybut-2-ene

              CH3  O
               |      ||
3CH2 = 2C – 1C –OC2H5
Ethyl 2-methylprop-2-enoate

 

              CH3  CH3
               |      |
4CH3 – 3CH – 2CH –1CH2NH2
2,3-Dimethylbutan-1-amine

            O
             ||
1CH3 – 2C – 3CH –4CH – NH2
                     |          |
                   C2H5     CH3
3-Ethyl-4-methylpentan-2-one

                                   O
                                   ||
4CH3 – 3CH – 2CH2 –1C – Br
              |
             CH3
3-Methylbutanoyl bromide

3CH2 – 2CH – 1CH2 –OH
              |
             C6H5
2-Phenypropan-1-ol

              CH3
              |
1CH3 – 2C – 3CH –4CH2 – 5CH2 – 6CH2
              |       |         |
             CH3   CH3     I
    4-Iodo-2,2,3-trimethylhexane

                                             CH3
                                              |
6CH3 – 5CH2 – 4CH –3CH – 2C – 1CH3
                         |         |          |
                        Cl       CH3    OH
    4-Chloro-2, 3-dimethylhexan-2-ol

APPENDIX 3
SOME USEFUL CONVERSION FACTORS
Common Units of Mass and Weight
1 pound = 453.59 grams
1 pound = 453.59 grams = 0.45359 kilogram,
1 kilogram = 1000 grams = 2.205 pounds
1 gram = 10 decigrams = 100 centigrams
= 1000 milligrams
1 gram = 6.022 × 1023 atomic mass units or u,
1 atomic mass unit = 1.6606 × 10-24 gram
1 metric tonne = 1000 kilograms = 2205 pounds
Common Units of Volume
1 quart = 0.9463 litre, 1 litre = 1.056 quarts
1 litre = 1 cubic decimetre = 1000 cubic centimetres
= 0.001 cubic metre
1 millilitre = 1 cubic centimetre = 0.001 litre
= 1.056 x 10-3 quart
1 cubic foot = 28.316litres = 29.902 quarts
= 7.475 gallons

Common Units of Energy
1 joule = 1 × 107 ergs
1 thermo chemical calorie* = 4.184 joules
= 4.184 × 107 ergs = 4.129 × 10-2 litre-atmospheres
= 2.612 × 1019 electron volts
1 ergs = 1 × 10-7 joule = 2.3901 × 10-8 calorie
1 electron volt = 1.6022 × 10-19 joule
= 1.6022 × 10-12 erg = 96.487 kl/mol
1 litre atmosphere = 24.217 calories
= 101.32 joules = 1.0132 × 109 ergs
1 British thermal unit = 1055.06 joules
= 1.05506 × 1010 ergs = 252.2 calories
Common Units of Length
1 inch = 2.54 centimetres (exactly)
1 mile = 5280 feet = 1.609 kilometers
1 yard = 36 inches = 0.9144 metre
1 metre = 100 centimetres = 39.37 inches
= 3.281 feet = 1.094 yards
1 kilometer = 1000 metres = 1094 yards = 0.6215 mile
* The amount of heat required to raise the temperature of one gram of
water from 14.5°C to 15.5°C

1 Angstrom = 1.0 × 10-8 centimetres = 0.10 nanometer
= 1.0 × 10-10 metre = 3.937 × 10-9 inch

Common Units of Force- and Pressure
1 atmosphere = 760 millimeters of mercury
= 1.013 × 105 Pascals
= 14.70 pounds per square inch
1 bar = 105 Pascals
1 torr = 1 millimeter of mercury
1 pascal = 1 kg/ms2= 1 N/m2
Temperature
SI Base Unit: Kelvin (K)
0K = – 273. 15°C
? K = °C + 273.15°
? °F = 1.8(°C) + 32°
Note: All other units are per particle and must be multiplied by 6.022 ° × 1023 to be strictly comparable.