Lesson Note on Chemistry SS3 First Term

Chemistry Topics for Secondary School – Edudelight.com

SCHEME OF WORK CHEMISTRY SSS3

Weeks              TOPICS

1. Revision, Saturated Hydrocarbon Alkanes e.g Methane CH₄ – preparation, properties and uses, isomerism, IUPAC, Nomenclature.
2. Unsaturated hydrocarbon – Alkenes e.g ethane (C₂H₂) – Nomenclature, preparation, properties and uses.
3. Unsaturated Hydrocarbons, Alkynes e.gethyne (C₂H₂)-Nomenclature, preparation, properties and uses.

4 – 5. Aromatic hydrocarbon, Benzene-structure, properties and uses, derivatives of Benzene e.g methyl benzene.Alkanols – sources, general molecular formula, nomenclature, classification, types, preparation, properties and uses. Test for alkanols.

6. Alkanoicacids – sources, nomenclature, structure, preparation, properties and uses. Alkanoates, general molecular formular, nomenclature, preparation, properties and Uses.

7. Fat and Oil as higher Esters, sources, properties and Uses. Detergents and Soaps.Structure, their mode and action.

8. Natural and synthetic polymers, polymerization(additional and condensation), plastics – Thermoplastic and Thermosetting polymers, Resins.

9. Carbohydrates – sources, general molecular formular, classification, properties and uses. Test for carbohydrates. Proteins – sources, structure, properties and uses, tests for proteins.

10.Amines and Amides , general molecular structure, preparation, properties and Uses.

11. Revision.

12.Examination

Reference Book

New School Chemistry for Senior Secondary Schools by Osei Yaw Ababio.

Practical Chemistry for Senior Secondary Schools by Godwin Ojokuku

Outline Chemistry for Schools & Colleges by Ojiodu C. C.

Chemistry Pass Questions for S.S.C.E and UTME.

WEEK ONE

Topic: Saturated Hydrocarbons

Content:  Alkanes e.g methane (CH₄)

            –  preparation – properties – Uses

            –    Isomerism

            –  IUPAC Nomenclature

Saturated Hydrocarbons

Saturated hydrocarbons are hydrocarbons consisting of  carbon chains with single bond between them  in which carbon joins with another carbon by single covalent bond e.g Alkanes ( like ethane C₂H₆, propane C₃H₈ )

            H          H                                             HHH

     H –  C          C – H                           H – C  –     C –     C – H

 H        HHHH

Alkanese.g Methane (CH₄)

The alkanes are aliphatic hydrocarbons.  They form homologous series of saturated hydrocarbons with general molecular formular of CnH₂n+2

EVALUATION

1.         What is saturated hydrocarbons?

2.         Name one example of alkanes.

Preparation of  Methane (CH₄).

Methane is prepared in the laboratory by heating ethanoate salt with corresponding alkalis e.g Sodium ethanoate and soda-lime.

Physical Properties

1. Methane is a colourless and odourless gas

2. It is slightly soluble in water.

3.  It is less dense than air

4.  It has no action on litmus paper

Chemical Properties.

1.         Combustion:-  Methane burns in air or oxygen to produce steam, carbon(iv) oxide and a lot of heat CH₄ + 2O₂            2H₂O  +   CO₂.

The general equation of alkanes for combustion is represented as

CxHy(g)   +   ( x + ^y/₄)O₂         ^y/ ₂H₂O(g)   +    xCO₂ (g).

2.         Substitutional reaction:-  With chlorine gas and bromme gas usually in the presence of ultra’-violet light ( as catalyst).

Uses

1.         Methane is used as fuel

2.         It is used for making hydrogen gas

3.         It is used in making carbon black

4.         Used in making carbon (iv) sulphide

5.         It is used in making hydrocyanic acid

6          The derivatives of methane e.gtrichloro-methane can be used as anesthetic in surgical operation.  Tetrachloromethane is an organic solvent.

Evaluation

1.         State  four (4) uses of methane

2.         Identify two (2) chemical properties of methane.

Isomerism.

This is the existence of two or more  organic compounds, (isomers) with the  same molecular formula but different structures.

– Isomers are compounds having the same molecular formula but different structural formula.

– As the number of carbon atoms in a molecule increases, the number of isomers also increases, for example, pentane has the following three isomers.

            H          H          HHH                             H          H          H          H

H          C          C          C          C          C      H             H          C          C          C          C   H

            H          H          H          H          H                      H          HH

Pentame-CH₃(CH₂)₃CH₃                                                 H        C     H

                                                                                                  H

                                                                                                   2 – methyl butane

                        H

               H –  C  – H

             H                        H

    H     C          CC     H

  H                      H             2,2- dimethyl propane.

                  H -C – H

                      H

TYPES OF ISOMERISM

1.  Structural Isomerism

2.   Stereo Isomerism.

The structural isomerism occurs in organic compound with the same molecular formula but different structural arrangement of the carbon atom.

Types of Structural Isomerism

1. Chain isomerism :-This is the kind of isomerism which occurs  due to the differences  in  the way by which the carbon atoms are arranged in the chain.

e.g         H        H          H          H                                  H          H          H         

        H-  C  –    C  –     C  –       C – H                            H-         C   –       C   –         C – H

              H     H           H          H                                  HH

                                                                                                       H – C – H 

                        Butane                                                                        

                                                                                                    H

                                                                                               2- methyl propane

ii. Functional isomerism:- This is the kind of isomerism which due to the difference in     functional group.

e.g            H     H                                                        H          H

          H-   C  –  C – OH                                                            H   C  –  O-     C-  H

                  H     HHH

Ethanol                                                                        Methoxyl methane.

iii.   Positional isomerism:-  This is the kind of isomerism which occurs as a result of the          difference in the way the functional group is positioned.

Example:  

                        H     H                                    H          H

               H       C     CCC   H  H – C –  C =  C –  C – H

                         H     HHHHHHH

                    But-1-ene                                        But-2- ene

2.Stereo Isomerism

Types of stereo isomerism

I.    Geometric Isomerism :-  This is the existence of compound with the same molecular formula but  different spatial structural formula.

e.g  CH₃CH₃

C  =  C                                                                                     CH₃               H

                                                                                                  C = C 

         H            H   Cis but-2-ene                                  H                CH₃    Trans-but-2-ene

II.  Optical Isomerism:-  They have  different configuration and they rotate plane polarized        light e.g.                H                                                          H

                               CH₃ – C – COOH                             HOOC – C – CH₃

                                      OH                                                           OH

IUPAC NOMENCLATURE

In IUPAC nomenclature, every name of organic compound consists of a ROOT, SUFFIX and PREFIX names.

ROOT NAME:

Name of the parent alphatic hydrocarbon with the longest carbon chain in a molecule .

SUFFIX NAME

Name of the principal functional group substituents on the longest carbon chain in a molecule.

PREFIX NAME.

Name of the other substituents on the longest carbon chain which are not functional group e.g 1- chloroethan – 1- ol.

1- chloro = Prefix

ethane = root

-1- ol Suffix

RULES FOR IUPAC NOMENCLATURE.

1.         Select the longest continuous carbon chain as parent hydrocarbon.

2.         Number the longest carbon chain. Starting from the end that gives lowest possible number to the suffix and then the prefix.

3. Indicate  the other substitents by prefixes, preceded by number to show their position on the carbon chain.

4. If the same alky or other substituents group occur more than once as side chain show how many are present by using prefix di,tri, tetra, etc. and indicate by various number the position of each group on the longest carbon chain.

5.         If there are several  different alkyl groups attached to the present chain, name them in order of increasing size or in alphabetical order.

                                   H           H       H

                                    C –           C –          C – H

                                    H                      H                         2 methyl propane

                                         H -C – H

                                             H

                               H    HHHH

                              H     C    CCCC   H                                        2- methyl pentane

                                     H     HHH

                                                            H   C   H

                                                               H

                H   HHH        CH₃C₂H₅  HH

  H –        C –  C –  C-    C  –     C  –      C  –    C –   C  – H

    H    HHH        C₃H₇    H       HH

3,3,-diethyl – 4- methyl 1-5 propyl octane.

6.  If there are halogens together with alkyl groups attached to the parent chain, name the halogen first in alphabetical order and the alkyl group as explained earlier.

                                      H    Cl

                                                                   1- bromo-2- chloro propan-2-ol.

               H      C –   C-  OH

                                  Br   CH₃

Evaluation

Name the following compounds.

1a.        H   HH

    H – C  – C  –  C  – H

          H   HH

b.  CH₃CHClCH₂OH

2.  List the rules for IUPAC Nomenclature.

READING ASSIGNMENT

New School Chemistry by O.Y. AbabioPg

WEEKEND ASSIGNMENT

1.  The structure of 1,2,3-trichloro-2-methyl butane is

a)      CH3   H       H       H                   b)                       Cl       Cl        Cl         H

 H-    C  –    C    –   C  –   C – H             H- C    –  C  –     C –       C – H

ClCl        H     HClClCl         H

c)     ClClCl    H                        d)                                   H       HHH

 H –  C-       C-        C  –   C  – H                                               H –  C –      C –        C-      C – H

        H H – C- H    HH                                             HHH

                                                                                                                  H – C- H   

                 H                                                                                           H

2.  Which of these compounds exhibits resonance ?

(a) Ethanol                   (b) Ethane        (c) Benzene      (d) Ethyne.

3. The solubility of alkane in organic solvent is due to presence of its

    (a) polar molecule                (b) non-polar molecule  (c) Low melting points  (d) low freezing            points.

4.  Which of these is alkane member?

    (a) Ethene               (b) Pecane        (c )Propyne        (d) Butanol

5.  The root in the organic compound below is:

                             H     HH

                        H- C –  C –     C –   H

H     H      OH.

 (a) Propane                 (b) Propan-1-ol (c ) Propanol       (d) hydrogen

THEORY

1.         Write briefly on the following:

a.         Cracking

b.         Isomerism

c.         Homologous Series

d.         Stereo Isomerism

e.         Optical Isomerism.

2.         Name the following compound

1. CH₂(OH)CH(OH)CH₂OH
2. C₂H₄CL₂

Chemistry Topics for Secondary School – Edudelight.com

WEEK TWO

Topic: Unsaturated Hydrocarbons – Alkenes

CONTENT

• Nomenclature
• Preparation
• Properties
• Uses.

UNSATURATED HYDROCARBONS

These are hydrocarbons in which carbon atoms join with each other by multiple bonds.  The multiple bond can be double bonds e.g Alkene or triple bonds e.g Alkyne.

1. Ethene2 .Ethyne

                        H – C = C – H                                      H – C = C – H

H   H.  

                                    Alkenes e.gEthene

Nomenclature

The process of naming in alkene is obtained by substitute “ane” in alkane with ‘ene’ e.g Ethane changes to Ethene, propane to prepene

PREPARATION (Lab. Preparation)

1.  Ethene is prepared by heating ethanol with excess concentrated tetraososulphate VI      acid at 170^o C. The acid acts as a dehydrating agent by removing water from the ethanol .   Thus the process is called dehydration.

The reaction occurs in two stages

            C₂H₅OH(aq)  + H₂SO₄ (aq)               C₂H₅HSO₄ + H₂O

C₂H₅HSO₄               C₂H₄+ H₂SO₄.

The overall reaction is represented by the equation .

C₂H₅OH  ^H2^SO4 C₂H₄+ H₂SO₄

-H₂O

2.  Ethene can be prepared through cracking of Alkane   e.g C₃H₈           C₂H₄ + CH_4.

3.  By dehydration

            e.g                               H          H          Cl            H       H

                                        H –  C –   C – H                            C   =   C  + HCL

                                               H      Cl                                H       H

Physical Properties

1.         Ethene is a colourless gas with faint sweetish odour .

2.         It is sparingly  soluble in water

3.         It is slightly less dense than air

4.         It has no action on litmus paper

Evaluation

1.         Write four (4) physical properties of Ethene

2.         How would you prepare a jar of ethane gas in the laboratory?

CHEMCIAL PROPERTIES

1.         Combustion

Ethene undergoes combustion/oxidation in air or in the presence of oxygen and produce carbon(iv)oxide and steam .

            C₂H₄  +  3O₂               2CO₂ + 2H₂O.

2.         Additional reaction

a.         With hydrogen known as hydrogenation

                        H          H                                  H        H

                H-     C= C –   H   +      H₂            H –   C  –      C – H

Ethene                                        H         H          Ethane

b.         With halogen know as halogenation

                        H          H          HH

H  –  C =  C- H  +  Cl₂                   H   C –  C –  H

Ethene                         ClCl      1,2- dichloroethane

c.          With Halides known as hydrogenation

            e.g  H- C = C – H + HBr                                  H          H

                        H    HH    C         C – H

                        ethene                                                H        Br           1-Bromoethane.

d.         With acidified /Alkaline KMnO4 known as hydroxylation.  It decolourses acidified KMnO₄, but turns alkaline KMnO₄ to green and result to ethane -1,2- diol.

                                                                                                     OH     OH

                        H – C = C – H    +    KMnO₄                       H –     C   –    C  – H

                            H     H                                                           HH

                                                                                             Ethane-1,2-diol (glycol)

e.         With Hydrogen peroxide in the presence of osmium trioxde to form ethan -1,2- diol.

OH  OH

                              H –    C  =  C  + H + H₂O₂          H – C –  C  – H

                                         H      HHH

                                 Ethane -1,2- diol.

f.          With conc. H₂SO₄ known as hydration to produce fuming liquid of ethyl hydrogen sulphate.C₂H₄  + H₂SO₄               C₂H₅HSO₄

          When ethyl hydrogen sulphate is hydrolyzed, tetraoxosulphate (vi) acid and ethanol            are produced.C₂H₅SO₄                C₂H₅OH + H₂SO₄

g.         Ethene gas decolourizes bromine water to produce bromoethanol.

                                                                                     H      H

          H – C = C – H   +   HBrO                             H – C –    C –  H

               H   H          (radiation brown)                  Br     OH  

Bromoethanol.

            Similarly:

                                                                                        H     H

                        H-C  = C – H    +    HClO                 H – C –   C – H

                                                (Brown)

                                                                        Cl   OH

Chloroethanol

h.         Polymerization of ethane to produce polythene.

                H      HHHHH

               C   =  CC  –  C  – C  –   C

               H       HHHHH

                                                                polyethene

i.          With ozone known as ozomolysis to from etheneozomides.

            e.g                   H          H                                                      O

            C  =      C     + O₃                                 H₂C         CH₂

                                                              Ozone                            

                                H         H                                                      O   

EtheneEtheneozonide

j.          Ethene can also undergo additional reaction with oxygen in the presence of silver catalyst at about250^oC to form epoxy ethane.

                     H    H                              HH

              H – C =   C –  H   + ½ O2            H – C  –  C  – H

                                                                       O

USES

• Used in the manufacture of plastics.
• Used in making synthetic rubber.
• Used to hasten the ripening of fruits.
• Used in the production of other organic compounds e.g halo-alkane,ethane, ethanol.

Evaluation

1.  Describe the reaction of ethane with the following:

1. Bromine water
   1. Chlorine water
   1. Acidified KMnO₄

2.   State four (4) uses of Ethene.

READING ASSIGNMENT

New School Chemistry by O.Y. AbabioPg 459-492

WEEKEND ASSIGNMENT

1.  The name of the organic compound with the structure below:

                                                                        CH₃            H

C  =  C

                                                                        H               CH₃

1. Cis- but-2-ene
2. Trans –cis-but-2-ene     
3. Trans-1-2- but-2-ene
4. 1,2- dimethyl ethane.

2.  In the reaction given below:

            C₂H₅OH    ^{Conc H}₂^SO₄       C₂ H₄Conc H₂SO₄is  acting as

                                  -H₂O

A.  oxidizing agent                    B reducing agent          C. Dehydrating agent    D. Drying agent.

3.  One of the following is not a chemical property of ethane.

     (a ) Polymerization             (b) Substitutional    (c ) Hydration     (d)  Addition.

4.  Function of the empty bottle during the preparation of ethane gas is

        (a) to remove oxygen    (b) to remove CO₂     ( c) to prevent sucking back of the gas            (d) None of the above.

5.  Additional reaction of hydrogen and ethene is known as

        (a) polymerization              (b) additional    (c) combustion   (d) hydrogenation 

Theory

1. Describe two (2) methods of obtaining ethene industrially.

2a. Write and name the geometric isomers of compound with the molecular formular  C₅H₁₀

  b. With chemical equation only, show how ethane reacts with the following:

            – ozone

            – oxygen

            – alkaline KMnO₄

            –  Conc. H₂SO₄
Chemistry Topics for Secondary School – Edudelight.com

WEEK THREE

Topic: ALKYNES e.gEthyne

Alkynes are the  homologous series of unsaturated hydrocarbon  with a general molecular formua CnH_2n-2.

Alkynes show a high degree of unsaturation than alkenes, hence,t hey are chemically more reactive than the corresponding alkenes or alkanes.

Examples are :

                                                                        H

            H – C = C – H                          HC  – C =  C- H  

[

            Ethyne.                                   H                 prop-1-yne

ETHYNE

Ethyne is the first member of the alkyne series.  It has a molecular formula, C₂H₂, and a structural formular of HC = CH.

Laboratory Preparation

Ethyne is usually prepared in the laboratory by the action of  cold water on calcium carbide.  The reaction is carried out on a heap of sand to prevent the flask from cracking as a result of the large quantity of heat evolved.

Evaluation

1.         Write and name all possible structure of hexyne

2.         How can you prepare a few jars of ethyne in the laboratory?

Nomenclature:  The naming of alkyne are obtained by substituting “ane” in alkaens with ‘ene’.

Physical Properties

1.         Ethyne is a colourless gas with a characteristic sweet smell when pure.

2.         It is only sparingly soluble in water

3.         It is slightly less dense than air.

4.         It is unstable and may explode on compression to liquid.

Chemical Properties

1. Combustion :-  it undergoes combustion reaction in air to form water and carbon(iv) oxide

            2C₂H₂ + 5O₂2H₂O  +      4CO₂.

NB:  In limited air, it burns with very smoky and luminous flame because of its high carbon content. But in plenty of air and appropriate proportion, it burns with non-luminous very hot flame of about 3000^oC.

2.  Additional Reaction :-Ethyne undergoes addition reaction to produce unsaturated      product with double bonds and then a saturated compound  with single bond.

a. With hydrogen in the presence of nickel as catalyst.

                                                                  H   HHH

                        H- C =  C – H  + H₂          H – C = C – H   + H₂                  H – C    – C  – H

ethene                                    H      H    Ethane

b. Halogenation:  e.g   Cl₂, Br₂,  I₂

ClClClCl

              H- C = C – H + Cl₂            H – C = C – H  +  Cl₂         H – C –   C – H

                                            1,2- dichloroetheneClCl1,1,2,2tetrachloroethane

                                                   Br    BrBrBr          

            C = C – H  +  Br₂        H –   C  =  C – H   +   Br₂           H–C  –  C – H

                                        1,2 – dibromoethane                       Br    Br                                                                                                                                                 1,1,2,2 -tetrabromoethane.

c. Addition of Halides;

     Hydrogen halide reacts with ethyne to produce halo-alkene and further halogenation     produce halo-alkane.

    E.g:                                                                        ClCl                              

H – C = C – H  +HCl       H – C = C – H   +   HCl        H – C –   C – H

H   Cl                                 H    H.

Chloroethene             1,2- dichloro ethane.

d.Addition reaction with water through dilute tetraoxosulphate (vi) acid in the presence of     CuSO₄  as catalyst to form ethanol.

                                                   H      OH                                    H      H

H-C=C-H   + H₂O                H-  C   =   C – H                         H- C –     C – H

                                                                                              H     OH      Ethanol

                                          Ethenol

e. Addition reaction with alkaline KMnO₄ added to ethyne, it first turns to green from      purple and then to colourless.

                                                                                      O       O

                        H – C = C – H  +  4[O]                  HO – C   =  C- OH

KMnO₄                Ethane dioc acid.

3. Polymerization

 In the presence of complex organic –nickel as catalyst to produce benzene.

            3 C₂H₂        C₆H₆

            3 (H – C = C – H )         C₆H₆

4. Substitutional Reaction

a.  Withammomiacal solution of copper (1) chloride to form reddish brown copper (I)                dicarbide

            C₂H₂  +  2CuCl          Cu₂C₂  +  2HCl

            H – C = C – H + 2CuCl         Cu – C = C- Cu + 2HCl

b. With ammomiacal silver trioxonitrate (v) to form white silver dicarbide

            C₂H₂ + 2AgNO₃Ag₂C₂  + 2HNO₃.

            H- C = C – H + 2AgNO₃          Ag – C = C – Ag + 2HNO₃.

N.B:  Alkynes can be  distinguished from alkene by reacting with ammomiacal metals of           copper(I) chloride and silver trioxonitrate (vi).

USES

1. It is used to produce oxyacetylene flame for cutting and welding of metals
2. Used in the manufacture of PVC plastics
3. It is used in miner’s lamp
4. Used in making synthetic fibre
5. It is also used in making artificial rubber

Test for Unsaturation

Unsaturated compound decolorizes bromine water.

Evaluation

1. Give a chemical test to distinguish between alkyne and alkene.
2. Describe a test for unsaturated compounds

READING ASSIGNMENT

New School Chemistry by Y. O Osei  yawAbabio Page

WEEKEND ASSIGNMENT

1.         The concentration of hydrogen ion in a neutral solution is

            (a) 10^-6 moldm^-3(  b) 10^-7moldm^-3      (c)  5 x 10^-7 moldm^-3    (d) 1 x 10^-8mol dm^-3

2.         Hydrogen can be prepared in a large scale using the

            (a) Harber’s process     (b) Down’s process   (c ) Bosh Process   (d) Contact Process.

3.         Which of the following hydrocarbons is alkyne?

            (a ) C₂H₄           (b) C₂H₆            (c) C₂H₂            (d) C₃H₈

4.         The final product of complete reaction between ethyne and hydrogen gas is

            (a) ethane                    (b)methyl ethane         ( c) ethane       ( d) hydroethyne

5.         Ethynepolymerises in the presence of organomickelcomplext as catalyst to form

            (a) polythene               (b) benzene                  ( c) polythene    (d) methyl benzene.

Theory

1.         a. Calculate the H⁺ of a solution whose PH is 5.

            b. State three (3) uses of ethyne

2.         a. With the aid of labeled diagram, describe the laboratory preparation of ethyne.

            b.  Give a chemical test to distinguish between ethane and ethyne.

WEEK FOUR

TOPIC: AROMATIC HYDROCARBONS

CONTENT

Benzene, structure, properties and Uses

Derivative of Benzene

Aromatic Hydrocarbons

These are hydrocarbons that have the same structure as benzene.

Benzene: Benzene is a typical aromatic compound with molecular formula of C₆H₆.  It has the structure of:

Preparation:- 

1.  From coal tar:  The destructive distillation of coal produced coal tar which contain      benzene

2.  From petreoleum; The dehydrogenated of alkane using valladim (v) oxide (v₂O₅) as     catalyst at 500^oC and 20 atmos give benzene

            C₆H₁₄     V₂O₂C₆H₆  +  4H₂

   The process is known as catalysticreforming .

3.  From polymerization of ethyne

            3 ( H – C = C – H )           C₆H₆

Evaluation

1. Describe three (3) ways of preparing benzene.
2. Draw the structure of benzene.

Physical properties

1.         It has a pleasant odour.

2.         It has boiling point of 80^oC.

3.         Benzene can dissolve in water.

4.         It burns with  sooty flame.

Chemical Properties

Benzene can undergo both additional reaction and substitutional reaction.

1. Additional Reaction.

 i.   Hydrogenaton:  Benzene reduces to cyclo-hexane if hydrogen gas is passed through       finely divided mickel at 150^oC.

 ii.   Halogenation:  In the presence of ultra-violet light, benzene reacts with halogen to         produce cyclic compound.

                                    C₆H₆  + 3 Cl₂       UV  

                                     Light

2.  Substitution Reaction.

NB.  Benzene undergoes substitution reaction due to the presence of its single bonds.

i. Halogenation  e.g Cl₂, Br₂, I₂

                                    +  Br₂

            Benzene                                              Bromobenzene

ii. Nitration:  This occurs in the mixture of HNO₃ and H₂SO₄ together with benzene

                                                HNO₃                Nitrobenzene.

iii.  Sulphonation:- Benzene reacts with conc, H₂SO₄ to form benzene sulphonic acid.

iv.  Alkylation:-  It involves reactions of benzene with halo-alkanes in the presence of AlCl₃.

Uses.

1.         It is used as a solvent to dissolve organic.

2.         It is used as fuel in petrol.

3.          It is used in the manufacture of aromatic compound e.g. benzoic acid.

Evaluation

1. State two (2) uses of benzene

2. Identify two (2) chemical properties of benzene with examples.

Derivatives of Benzene

          Methyl benzene                                           Ethyl benzene

            (toluene)                            

1,2- dimethyl benzene                                                  1,4- dimethyl benzene

Phenol                                      Nitrobenzene                                        Chlorobenzene

Napthalene

(C₁₀H₈)

Evaluation

1.         Give another name to the following  compounds

            (a ) Phenol                   (b) Toluene     

2.         State  four (4) derivatives of benzene.

READING ASSIGNMENT

New School Chemistry By .O.Y. Ababio, pg 492-494.

WEEKEND ASSIGNMENT

1.         Which of the following is the structure of benzene

2.         Benzene can be prepared from the following except

            (a) Coal tar                   (b) petroleum               ( c) Alkanol       (d) Ethyne

3.         Benzene  can undergo additional reaction due to presence of

            (a) double bonds          (b) single bonds           ( c) hydrogen     ( d) carbon.

4.         Benzene undergoes the following reaction except.

            (a) substitution (b) addiction                ( c) Hydrogenation   ( d) polymerization

5.         The technique used in separating a mixture of common salt  and water is

            (a) evaporation (b) sublimation (c) decantation      (d) chromatography.

Theory

1.         a. State two (2) uses of Benzene

            b. identify two (2) physical properties of benzene.

2.         a.  How would you prepare benzene?

            b.  State two (2) chemical properties  of benzene.

Chemistry Topics for Secondary School – Edudelight.com

WEEK FIVE

TOPIC: ALKANOLS

CONTENT

-Source

-General molecular formula

-Nomenclature

– Classification  

-Types, Preparation, Properties and Uses.

Test for Alkanols

SOURCES OF ALKANOLS

–           From destructive distillation wood.

–           From starchy food and sugar

General molecular formular

Alkanol is a homologous series with general molecular formular of C_n H_2n+1OH or ROH.

Or (C_nH_2n+2O).

Nomenclature:

The names of alkanols are obtained by substituting “e” in alkanes with “Ol” in alkanol e.g. methanol

(CH₃OH), ethanol (CH₃CH₂OH).

Classification

The alkanols are classified based on the number of alkyl groups directly linked to the carbon atom

holding the hydroxyl group.

1. Primary alkanols (1⁰):  It has only one alkyl group attached to the carbon atom that carries the

   hydroxyl group e.g.                                     H

                                                                         R –       C     OH

                                                                                    H

                        OR

                        H          H                                              H

                H     C          C   OH          or     H     C   OH

                        H          H                                              H                     

                  Ethanol                                                Methanol

II. Secondary alkanols (2⁰):-  They have 2 alkyl groups directly linked with the carbon atom holding the hydroxyl group e.g.

                        H          H          H                                              H

            H          C          C          C          H          or         R          C          R¹

                        H          OH       H                                              OH

            Propan – 2-ol

III. Tertiary alkanols (3⁰ ):  the alkanols here have 3 alkyl groups attached to the carbon atom holding the hydroxyl group

                                    CH₃                                           R¹

                        CH₃       C          CH₃         or       R          C          OH

                                    OH                                           R¹¹      

                            2 – methylpropan -2 –ol

The R¹, R¹¹ are alkyl groups which may be the same or not.

N.B:      Examine the structure of the alkanol, identify the carbon atom bonded to the –OH, count the number of alkyl groups that are directly attached to the carbon atom.  Then you can say whether it is 1⁰, 2⁰ or 3⁰.

EVALUATION

1.         Name the functional group in the alkanol.

2.         Give an example each by writing the structure and names of the classes of alkanols.

Types of alkanol

The type of alkanols is determined by the number of the hydroxyl group –OH, present in the molecule.

1.         MONOHYDRIC ALKANOLS:  This type has only one –OH, present in its molecule

e.g. C₂H₅OH, C₃H₇OH e.t.c.

2.         DIHYDRIC ALKANOLS:  This type has two of –OH group per molecule e.g.

                        H                                              H

            H          C          OH                   H          C          OH

            H          C          OH                   H          C          H

                        H                                  H          C          OH

                                                                        H

Ethan -1, 2- diol                             Propan 1, 3-diol

• POLYHYDRIC ALKANOLS:  This type has three or more.  OH groups per molecule e.g. glycerol.

                      H                                                                     H

            H          C          OH                                           H          C          OH

            H          C          OH                                           H          C          OH

            H          C          OH                                           H          C          OH

                        H                                                          H          C          OH

                                                                                    H          C          OH

                                                                                    H          C         OH

                                                                                                H

PREPARATION   e.g. ethanol

1.         Laboratory preparation

            –           Hydrolyzing ethyl esters with hot alkali

            –           Reducing ethanol with nascent hydrogen

2.         Commercial preparation

            –           From ethene

Ethene is obtained by the cracking of petroleum. It is then absorbed in 95% H₂SO4 at 80⁰C and

30 atoms to form C₂H₅HSO4

C₂H₄  +  H₂SO₄             C₂H₃HSO₄

The C₂H₃HSO₄ is bedded in water to produce ethanol; C₂H₃HSO4 + H₂O             C₂H₃OH + H₂SO₄.

The ethanol is distilled off leaving the acid behind which can be used again.

-Preparation by fermentation ethanol is prepared industrially from raw materials containing

starch or sugar by the process of fermentation.

-The fermentation is an enzymatic process which involves the decomposition of large organic

molecules to simple molecule by micro-organism.

-The common micro-organism used is YEAST

EVALUATION

1.         Name three (3) types of alkanol and give one example each.

2.         State two methods by which ethanol can be prepared industrially.

PRODUCTION OF ETHANOL FROM STARCHY MATERIALS

(e.g. rice, potatoes, maize etc)

The following steps are involved;

• Crush and pressure cook the starchy materials.
• Extract the starch granules by mixing with water.
• Allow the starch granules to settle and decant
• Treat the starch granules with malt (a partially germinated barley which contains the enzyme, DIASTASE) at 50⁰C for I hour.
• The starch is then converted to MALTOSE. 2(C₆H₁₀O₅)n + nH₂O    nC₁₂H₂₂O₁₁

Then add yeast at room temperature for some time (at least one day).  Yeast contains two enzymes,

namely MALTASE and ZYMASE.  Maltase converts maltose to two glucose units, while zymase converts the glucose to ethanol and carbon (iv) oxide.

C₁₂H₂₂O₁₁  +  H₂O  ^maltase                2C₆H₁₂O₆

C₆ H₁₂ O₆    ^Zymase                    2C₂H₃OH   +   CO₂

                                                  Ethanol

EVALUATION

1.         Describe fully, the production of ethanol from a named starchy material/food.

2.         What type of chemical reaction is involved in fermentation of sugar?

PHYSICAL PROPERTIES

1.         Ethanol is a colourless volatile liquid.

2.         It is soluble in water.

3.         It has boiling point of 78⁰C.

4.         It has no action on litmus paper.

CHEMICAL PROPERTIES

1.         Combustion:  the lower members of alkanols burn with clean flames in plenty air

            2CH₃OH  +  3O₂               2CO_{2            4} +H₂O

2.         Oxidation

            The products of oxidation depend on the structure of the alkanol.

–           Primary alkanols are oxidized to alkanol first and then to alkanoic acid in the presence of oxidizing agent e.g KNnO₄

            CH₃CH₂OH        ^O           CH₃CHO            ^O           CH₃COOH

–           Secondary alkanols oxidize to ketone e.g.                   

            R                                                          R

R          C          OH       [O]                    R      C   = O  +  H₂O

            H                                 

            CH₃                                           CH₃

CH₃       C          OH         [O ]               CH₃       C  = O  +   H₂O

            H

Propon-2-ol                              propanone

–           Tertiary alkanols are not oxidized because there is no carbon-hydrogen bond to be broken for the oxidation to take place.

N.B:      Note the colour change of oxidizing agent if acidified.

–           Purple KMnO₄ changes to colourless.

–           Orange K₂Cr₂O₇ turns green.

3.         Esterification

This is the reversible reaction between alkanol and alkanoic and to produce ester.  The reaction is catalysed by conc H₂SO₄ e.g. CH₃CH₂OH  +  CH₂COOCH₂CH₃  +  H₂O

4.         Dehydration

            Alkanols are dehydrated to alkenes in the presence of conc H₂SO₄

e.g. CH₃CH₂OH    + conc H₂SO₄           CH₃CH₂HSO₄  +  H₂O

CH₃CH₂HSO_{4170 C}           C₂H₄  +  H₂SO₄

5.         Reaction with sodium and potassium

sodium and potassium react vigorously with alkanols to liberate hydrogen gas and form corresponding organic salt of sodium and potassium. 

E.g.2C₂H₃OH  +  Na              2C₂H₃ONa  +  H₂

            N.B:   If sodium ethoxide reacts with water, it hydrolyses to ethanol and alkaline solution of NaOH.

6.         Reactions with the chlorides of phophorus:  Ethanol reacts vigorously with PCl₅ in the cold

to produce time of HCl and chloroethanevapour  C₂H₅OH + PCl₅         C₂H₃Cl  +  POCl₃  + HCl

            -PCl₃ gives a similar reaction, but less vigorous C₂H₅OH  +  PCL₃           3C₂H₅Cl   +  H₃PO₃.

USES OF ETHANOL

1.         It is used as organic solvent

2.         It is the main constituent of methylated spirit used to clean wounds and to dissolve paint.

3.         It is used as petrol addictive for use as fuel in vehicles.

4.         Used to manufacture other chemicals such as ethanol and ethanoic acid.

5.         It is used as ingredient in making alcoholic drinks e.g. beers, wines and spirits.

6.         It is used as anti-freeze in automobile radiator because of its low freezing point (-117⁰C).

TEST FOR ALKANOLS

–           It librates hydrogen gas on reacting with sodium methal.

–           It changes to alkanoic acid (primary alkanol) on exposure to air or reacting with oxidizing agent.

EVALUATION

1.         State five (5) chemical properties of ethanol.

2a.       Identify two (2) physical properties of ethanol

  b.       State two (2) uses of alkannol.

READING ASSIGNMENT

–           New School Chemistry By O.Y. Osei Yaw Ababio pages 496-501

WEEKEND ASSIGNMENT

1.         The functional groups of the alkanol is

            A.  CnH_{2n + 1} OH     B.  carboxylic group    C.  hydroxyl group    D.  CnH_{2n+ 2}

2.         Primary alkanols are oxidized to carbonylic acid, secondary alkanols are oxidized to alkanones while tertiary alkanols are    A.  oxidized to alkanols    B.  oxidized to alkanones    C.  not oxidized    D.  oxidized to alkene

3.         The soluble of alkanols in water is due to

            A.  the covalent nature    B.  hydrogen bonding    C.  their low melting point 

D.  their low melting point

4.         When acidified KMnO4 is used as oxidizing agent for alkanol, the colour change observed is

            A.  yellow to red     B.  purple to colourless    C.  orange to green    D.  white to black

5.         Which of the following enzymes converts glucose to ethanol?

            A.  maltose       B.  zymase        C.  diastase       D.  amylase

THEORY

1(a)      Write the structural formula of two named secondary alkanols.

  (b)     Explain the structural difference between primary and tertiary alkanols.

2(a)      What is fermentation?

  (b)     Describe the preparation of ethanol from table sugar.

WEEK SIX

TOPIC: ALKANOIC ACIDS

CONTENT      

Sources

 Nomenclature

 Structure

 Preparation

Properties and Uses

ALKANOATES

 General molecular formula, nomenclature,  preparation,  properties and uses.

SOURCES:

The alkanoic acid or carboxylic acids are also called fatty acids because some of them are found in natural fats and oils.  They contain the functional group called carboxy group.

NOMENCLATURE:

The IUPAC name of each homologue is obtained by changing the “-e” endind of the corresponding alkane to “-oic” acid e.g. mathanoic, ethanoic etc.

STRUCTURE:

Alkanoic acid has a general molecular fomular of CnH₂n + 1COOH where n > 0. or RCOOH.  Thus it has the following structure.

                                    O

                           RC  

                                       OH

E.g.Ethanoic acid CH₃COOH

                                    H         

                                                   O

                        H          C       C

                                    H            OH

PREPARATION   e.g.Ethanoic acid

Ethanoic acid can be prepared by the complete oxidation of ethanol by acidified sodium heptaoxo dichromate (VI) solution.  The oxidation reaction is a two stages of reaction

I.          Ethanol oxidized to ethanol;    CH₃CH₂OH             O₃         CH₃CHO

II.         Ethanol oxidized to ethanoic acid;  CH₃CHO        O₃          CH₃COOH

            Or

            CH₃CH₂OH  +    [O]           CH₃CHO  +    [O]               CH₃COOH

PHYSICAL PROPERTIES

1.         It is colourless liquid with a sharp and pungent smell.

2.         It has sour taste.

3.         It is soluble in water.

4.         It freezes into ice-like at temperature below 17⁰C therefore called gluciaethanoic acid (anhydrous ethanoic acid).

5.         It has boiling point of 118⁰C

6.         It turns blue litmus papers to red.

CHEMICAL PROPERTIES

1.         It libratescarbon(IV) oxide from either trioxocarbonate (IV) or hydrogen trioxocarbonate (IV) salts.  2CH₃COOH  + Na₂CO₃           2CH₃CONa  +  H₂O + CO₂.

2.         It librates hydrogen gas when it reacts with highly electropositive metals e.g.

Mg &Ca;              2CH₃COOH + Ca             (CH₃COO)₂Ca + H₂.

3.         As an acid, it neutralizes boxes or alkalis to form salts known as ethanoate and water only

CH₃COOH + NaOH             CH₃COONa + H₂O.

4.         It reacts with alkanols to form ester e.g. CH₃COOH + CH₃CH₂OH     CH₃COOCH₂CH₃ + H₂O

5.         Reduction:

            It can be reduced to ethanol in the presence of lithiumtetrahydridoaluminate III as

reducing agent (LiAlH₄)

            CH₃COOH  + 4H          CH₃CH₂OH + H₂O

6.         It reacts with chlorme successively to form chloroethanoic acid e.g.

            CH₃COOH       +  Cl₂               CH₂C_lCOOH   +    HCl

            CH₂ClCOOH   +   Cl₂               CHCl₂ COOH  +HCl

            CHCl₂ COOH  +   Cl₂               CCl₃COOH     +    HCl

EVALUATION

1. (a) State four (4) chemical properties of ethanoic acid.

(b) Give two (2) physical properties of ethanoic acid.

2. How would you prepare ethanoic acid in the laboratory.

CLASSIFICATION OF ALKANOIC ACID

Alkanoic acids are classified based on the number of carbonxylic groups present per molecules.

1. Monocarboxylic Acids:  these have one carboxylic group per molecule e.g.

methanoic acid (HCOOH)

       O

                        H          C         

                                           OH

            Ethanoic acid CH₃ COOH

                                    H

                                                       O

                        H          C          C

                                    H                 OH

2.         Dicarboxylic Acids:  these have two carboxyl groups per molecules e.g. ethan -1, 2-dioe acid

 (oxalic acid)

            COOH               O          O

                        or                  C     C

            COOH             HO                  OH       

3.         Tricarboxylic acids:  these have 3 carboxylic acid per molecule e.g. 2-hydroxy propan 1,2, 3-

tricaboxylic acid.

                                H

                        H          C          COOH

                        HO       C          COOH

                        H          C          COOH

                                    H

N.B:      Two important aromatic caborxylicacid are

            (1)        Benzoic acid

            (2)        2-hydroxy benzoic acid

USES OF ETHANOIC ACID

1.         It is used in making compounds like cellulose ethanoate, dyes etc.

2.         It is used as organic solvent.

3.         It is used in the food industries for preserving and flavoring food.

4.         Used for coagulating rubber latex.

EVALUATION

1. Give three (3) classes of alkanoic acid.

2. State four (4) uses of ethanoic acid.

READING ASSIGNMENT

New School Chemistry by O.Y. pages.504-506

ALKANOATES

General molecular formula.

The alkanoates are called esters.  They have general molecular formula of RCOOR’.

It has structural formula of

                                     O

R     C

                                       OR

e.gethylethanoate CH₃COOCH₂CH₃

NOMENCLATURE

Naming of alkanoates are obtained by substituting “e” ending in alkane with “oates” in

alkanoates.

Preparation e.g. ethyl ethanoate .

Ethyl ethanoate is prepared by the esterification between ethanol and glaciusethanoic acid at 150⁰C  in the presence of concentrated tetraoxosulphate (VI) acid

C₂H₅OH + CH₃COOH                 CH₃COOC₂H₅ + H₂O

PHYSICAL PROPERTIES

1. Ethyl ethanoate is a colourles volatile liquid with a pleasant smell.

2. It is slightly soluble in water.

3..It has boiling point of 75⁰C.

CHEMICAL PROPERTIES

1.  Hydrolysis.

Ethyl ethanoate can be hydrolysed by water to produce ethanoic acid and ethanol.

CH₃COOC₂H₅  + H₂O                    CH₃COOH + C₂H₅OH.

N.B:If an alkali is used instead of water, it will produce the salt of the acid e.g.

     CH₃COOC₂H₅ + NaOH                 CH₃COONa + C₂H₅OH

2. REACTION WITH AMMONIA

Ethyl ethanoate reacts with ammonia to produce ethanol and thenamide

CH₃COOC₂H₃ + NH₃              C₂H₅OH + CH₃COOH₂

3. REDUCTION

Ethyl ethanoate can be reduced by hydrogen from lithium tetrahydridoalluminute (III) as reducing agent        CH₃COOC₂H₅ + 4[H]             2C₂H₅OH

USES OF ALKANOATES/ESTERS

– They are used as food flavours.

– Used in perfumes and cosmetics

– Used as solvent for cellulose nitrate .

– Used for quick-drying substances like paints, nail varnishes etc.

EVALUATION

1.Write the general structure of the ester.

2.Write a balanced equation for the reaction between propanol and butanoic acid.

    (a) Name the products formed.

    (b) What type of reaction is involved.

READING ASSIGNMENT

New School Chemistry by Osei Yaw Ababio page.504-509

WEEKEND ASSIGNMENT

1.         The name of (CH₃)₂ CHCOOH is

            A.   Propane acid    B. 2-methylhutanoic acid  C.          Dimethyl butanoic acid

            D.         Propanoic acid

2.         Citric acid appears in unripe orange while enthanwie acid appears in

            A. Unripe pawpaw   B. Carrot    C.  Vineger     D.  Rice

3.         Esters are employed in the following except.

            A.  Making perfumes   B.  Making cement    C. Nail varnishes    D.  Making yeast

4.         An alkanoic acid reacts reversibly with an alkanol to produce.

A.  a salt    B.  an ester    C.  a sugar    D.  an alkene

5.         Ethan-1, 2-dioe acid is

            A.  a mineral acid    B.  dicarboxylic acid    C.  citric acid    D.  a soap

THEORY

1a.       Give the formula of ethanoic acid and indicate its functional group.

• Ethanoic acid reacts with both sodium hydroxide and ethanol, suing equations to comparethe reactions and classify the products.

2a.       Ethylethanoate reacts with both water and alkali; using equation to compare the reaction.

  b.     What happens when ethanoic acid is heated strongly with soda-line.

Chemistry Topics for Secondary School – Edudelight.com

WEEK SEVEN

TOPIC: Fats and Oils As Higher Esters.

CONTENT

Sources, properties and uses detergents and soaps

Structure, their mode and action.

Fats and oils belong to a general group of compounds known as lipids.

SOURCES:

Fats are solids that usually come from animals e.g. Tallow (mutton fat).  Oils are liquids that come from plants e.g. vegetable oil, coconut oil etc.  Both fat and oil are esters of the trihydricalkanol(propane -1, 2, 3- triol).

PHYSICAL PROPERTIES:

1. Fats have higher melting points due to the presence of higher proportion of esters of saturated fatty acid.

2. Oils have lower melting points because of the presence of esters of unsaturated fatty acid.

CHEMICAL PROPERTIES:

1.  Hydrogenation of oils.

   This is carried out in the presence of nickel as catalyst at 180⁰C to yield margarine.

2. Saponification:

    Hydrolysis of fats and oils with canotic alkali yields propane -1, 2, 3- triol and fatty acid          of sodium or potassium.

USES OF FATS AND OILS

1.   Fats are consumed as food.

2.  Oils are used to make margarine.

3.  Tallow (a fat) is used for making soaps.

4.  Ground nut oil and cotton seed oil are used for cooking.

5.  Coconut oil and palm oil are used for making soap and for cooking.

EVALUATION

1. Identify two (2) uses of fats and oils.

2. Write two (2) chemical properties and two (2) physical properties of fats and oils.

DETERGENTS:

Detergents are any substance which have ability to clean an object e.g. soaps, soap powders, washing liquids and water.

TYPES OF DETERGENT

1.SOAPY DETERGENTS: This is soap of sodium salt of fatty acid.

PREPARATION

Animal fat or vegetable bits are steam-heated with sodium or potassium hydroxide in a large container.  A concentrated Nuel solution is added to decrease the soluble of the soap – so that it comes out as hard

cake on cooling known as salting out

STRUCTURE:-

CH₃(CH₂)₁₆ COOCH₂

CH₃(CH)₂)₁₆ COOCH     +       3NaOH

                                      (Sodium Hydroxide)

CH₃(CH₂)₁₆ COOCH

                                                                                     Propane 1,2,3-triyltrioctadecanoate       

NATURE OF SOAP

Each molecule of soap has long hydrocarbon chain (alkyl) which is attached to ionic head of either COO^– Na⁺ or COO^–K⁺.  The alkyl tail hydrophobic) dissolves oil or organic solvent while the ionic soluble in water (hydrophilic).

ACTION OF SOAP (CLEANSING ACTION)

When soap solution is applied to a grease-coated piece of fabric, the soap molecule moves to thegrease spot.  The hydrophobic tails dissolve in grease while the hydrophilic dissolves in the water. 

The grease spot is lifted up and more soap particles dissolve the grease.

2.  SOAPLESS DETERGENTS

Soapless detergents are the more favouredall purpose cleansing agents nowadays. They are available as liquids or solids. The example of soapless detergent is alkyl benzenesulphates (ABS).  These are sodium salt of an     acid e.g. sulphonic acid.

STRUCTURE:

The molecule of detergent has hydrophobic tail and hydrophilic head.

The hydrophobic tail is a long chain hydrocarbon or benzene ring with long alkyl group.

The hydrophilic unlike soap can be positively or negative change or neutral.  The high solubility of soapless detergent in water is due to the presence of –SO₃^– Na⁺ in the molecules.

The soapless detergents are called synthetic detergents.  The raw materials are petrochemicals from refining crude oil.

                                                Hydrophilic

                                    R    –                SO₃^– Na⁺

                                    hydrophobic

                                    tail

  R is a long hydrophobic chain.

ACTION OF SOAPLESS DETERGENT

• They do not form scum or react with hydrogen ions.

EVALUATION

1.  Draw the structure of soapless detergent.

2. State one advantage of soapless detergent over soapy detergent.  

READING ASSIGNMENT

New School Chemistry by Osei Yaw Ababio pages.509-514     

WEEKEND ASSIGNMENT

1.         The structure of soap according to suponification process is

A.  CH₃(CH₂)₁₆COONa   B.  CH₃CH₂COOCa    C.  CH₃CH₂CH₂COONa

                        D.  C₂H₅COONa

2          . The example of soapless detergent is

            A.  alkyl     B.  ethylethanoate    C.  alkanol   D.  alkylbenzenesulphonates

3.         Hydrophobic tail of soap dissolves in grease while hydrophilic dissolves in

            A.  benzene      B.  water    C.  propanol    D.  kerosene

4.         Fats and oils belong to a general group of compounds known as ………..

            A.  glycerol       B.  soap                 C.  margarine          D.  lipids

5.         Hydrolysis of fat and oil to yield alkanol and soap is called …………

            A.  esterification     B.  hydrogenation     C.  hydrolysis     D.  saponification

THEORY

1.  Explain the structure of soapless detergent and its mode of action.

2.  Explain the following;

     (a)  saponification             (b) hydrogenation

WEEK EIGHT

TOPIC: NATURAL AND SYNTHETIC POLYMERS.                         

Polymerisation (addition and condensation) plastics.   

Thermosplastic and thermosetting polymers, resins.   

Polymer is the final product, macromolecule of high molecular mars.  It consists of a repeating units and its general molecular formula may be represented as [repeating units]_n where n is a very large whole number.

N.B:-    All polymers are macromolecules, but not all macromolecule but it is not polymeric.

NATURAL POLYMERS:

These are organic compounds which can be found in living thing e.g. carbohydrates like starch and cellulose and all proteins fats and oils are not large enough to be grouped as giant molecule or polymer.

SYNTHETIC POLYMERS

These are called plastics e.g. nylon polythene etc.

EVALUATION

1.  State a difference between natural polymers and synthetic polymer with example each.

2.  What is another name for synthetic polymer?

POLYMERIZATION

This is the process whereby two or more monomers link/join together to form a compound of

high molecular mass.

TYPES OF POLYMERIZATION

1. Addition polymerization:-  these occur when two or more of the same monomers join together    to form the polymer without elimination of any small molecules.         

CHARACTERISTICS OF MONOMER

–           It must be simple.

–           Unsaturated

–           There should be double bonds between the carbon atom.

e.g.n[CH₂CH₂ ]             ……..CH₂CH₂[CH₂CH₂]_nCH₂CH₂……

2.  CONDENSATION POLYMERIZATION:-  This is process whereby two or more smaller

    molecule (monomers) join together to form a giant molecule (polymer) with elimination of     trace/small molecule such as waters ammonia, hydrogen chloride.

TYPES OF CONDENSATION POLYMERIZATION

I.          COPOLYMER :-  This is formed from two condensing monomers of different types.

II.         HOMOPOLYMER :-  It is formed from monomers of the same type.

CONDITIONS NECESSARY FOR POLYMERIZATION

–           High temperature

–           High pressure

–           Presence of catalyst (initiator) e.g. oxygen, hydrogen peroxide.

EVALUATION

1. State two conditions necessary for polymerization of ethane to from polythene.
2. Mention one difference between additional polymerization and condensation polymensation.

PLASTICS

Plastics are synthetic which can be heated or pressured to form any shape.

THERMOPLASTIC

Thermoplastics are type of synthetic materials which can be heated and remoulded to any shape e.g. nylon, polythene, polypropene, Perspex etc.

THERMOSETS

Thermosets, on the other hands cannot be softened or melted by heat and remoulded once they are formed e.g. uera-methanal, bakelite.

   Thermoplastics and thermosets

Thermoplastics	Thermosets
Polythene	Bakelite
Polypropene	Urea-methanal
Polystyrene
Nylon
Terylene
Perspex

RESINS

This is obtained from the rubber tree.  The fluid obtained from the tree can be heated and changed to elastic solid known as rubber.  The rubber consists of 2-methyl but-1, 3- diene monomers known as isoprene.

                        CH₃

       nCH₂ =     C         CH    =    CH₂

     2 – methylbuta -1, 3-diene.

VULCANIZATION:

This is the process of heating natural rubber with sulphur to give rubber a greater tensile, strength, durability and elasticity over a wide range of temperature.

SYNTHETIC RUBBER:

Examples of synthetic rubbers are poly 2-chlorobuta -1,3diene, styrenebutadiene rubber (SBR), poly bute -1, 3- diene and poly 2-methyl propene.

EVALUATION

1. What is  resin?
2. State two (2) differences between thermoplastic and thermoset.

READING ASSIGNMENT

New School Chemistry by O.Y. Ababio pages 523-531

WEEKEND ASSIGNMENT

1. The following are examples of small molecules based during polymerization process.

     A.  acid                   B.  HCl          C.H₂O                   D.  NH₃

2. Polymerisation of ethane produces ……………

    A.  Perspex            B.  isoprene                C.  polythene         D.  ammonia

3. Bakelite is a good example of …………..

    A.  natural rubber     B.  thermoset     C.  thermoplastic   D.  additional polymerization

4. Starch and cellulose are good examples of …………

    A.  polythene           B.  natural polymer      C.         synthetic polymer    D.  food

5.  Joining together of smaller molecules to form a giant molecule is called ………..

     process.      A.  hydrogenation   B.  saponification   C.  esterification  D.  polymerization   

THEORY

1            (a)      What are the conditions necessary for polymerization.

              (b)     List two types of polymerization.

2            (a)      Write an equation for the preparation of polythene from ethane.

  (b)     What are the monomer present in the following:

                        –           polythene

                        –           polyvinyl/chloride

                        –           polytetrafluoro ethane

                        –           polypropene

WEEK NINE

CARBOHYDRATES:

Carbohydrates are naturally occurring organic compounds containing carbon, hydrogen and oxygenwith oxygen in the ratio 1:2 as in water.  The general molelcular formula of carbohydrates is C_x(H₂O)_y  or  C_xH_2yO_y.  Carbohydrates are generally polydroxyl aldehydes, ketones or any compound that on hydrolysis yields any of the polyhydroxides.  They are synthesized in green plants by photosynthesis.

CLASSIFICATION OF CARBOHYDRATES

                                                Carbohydrate

                         Simple sugar                             Complex sugar

                                                                                     (polysaccharides)

            Monosaacharide           Disacharides                   e.g. starch cellulose

            e.g. glucose                  e.g sucrose

EVALUATION

1.         Define carbohydrates.

2.         State one example each of simple sugar and complex sugar.

MONOSAACHARIDES

Monosaacharides are simple sugar with three to six carbon atoms per molecule.  The most common and important of these are the ones with six carbon atoms per molecule called the HEXOSES. They have the same molecular formula C₆H₁₂O₆ but different spatial arrangement.  Examples include glucose, fructose, galatose and mannose.

GLUCOSE (C₆H₁₂O₆)

Glucose, commonly known as grape sugar or dextrose, is present in grapes, in honey and the sap of plants.

 Glucose is synthesized by green plants during photosynthesis.

PREPARATION:-  Glucose can be prepared in the laboratory by the acid hydrolysis of starch. 

The starch is heated with dilute hydrochloric acid or tetraoxosulphate VI acid.  The acid functioning as hydrolyzing agent in the reaction.

                                    (C₆H₁₀O₆)n      nH₂O                nC₆H₁₂O₆

                                        Starch          Dil H­₂SO₄             glucose

Physical properties

1.         It is a white crystalline solid.

2.         It is soluble in water.

3.         It has sweet taste.

Chemical properties

1.         It dehydrates to black residue of carbon when with conc.  H₂SO₄       

            C₆H₁₂O₆                        6C + 6H₂O

2.         It is a strong reducing agent.  This is due to the presence of the –CHO group in the             molecule.

3.         It is readily fermented to ethanol and carbon VI oxide by the enzyme (ZYMASE) in yeast.

TEST:  Add a few drops of Fehling’s solution to 5cm³ of glucose solution in a test tube.  A brick-            red precipitate is obtained on boiling.

GLUCOSE STRUCTURAL FORMULA:

                                                H                     

                                                C          =          O          the functional groups in the

                                    H          C          H                      molecule are:

                                    HO       C          O                      -CHO and OH

                                    H          C          OH                   But -CHO determines the

                                    H          C          OH                   chemical properties

                                    OH       C          H

                                                H

FRUCTOSE (C₆H₁₂O₆)

An isomer of glucose is fructose.   Fructose is a non-reducing sugar (it contains the >CO group)

                                    FRUCTOSE STRUCTURAL FORMULA

                                                H

                                    H          C          OH       The functional groups in   the molecule are:

                                             C    =                    -C=O and –OH

                                                                             Chemical properties

                                    HO       C          H         

                                    H          C          OH

                                    H          C          OH

                                    H          C          OH

EVALUATION

1.         State two (2) physical properties of starch.

2.         Give difference between glucose and starch.

DISACCHARIDES:-

Disaccharides are simple sugar containing two molecules of monosaccharide per molecules.  Their general molecular formula is C₁₂H₂₂O₁₁.  Some important disaccharides and the component monosaccharide are;

            DISACCHARIDE                    COMPONENT MONOSACCHARIDES

            Sucrose (cane sugar)               Glucose + fructose

            Lactose (milk sugar)                 Glucose + galactose

            Maltose (malt sugar)                Glucose + glucose

SUCROSE:-

This is the common granulated sugar used at home to sweeten food.  It occurs naturally in plant and fruits e.g. pineapple, carrots sorghum, sap and sugar cane.

Preparation:  Sucrose is prepared industrially by;

1. Extraction of juice from sugar cane,
2. Concentration of the juice by evaporation,
3. Crystallization of the solid sugar from the concentrated juice and
4. Filtration of sugar crystals from the molasses.

PHYSICAL PROPERTIES:

1.         It is a white crystalline solid.

2.         It is dissolves readily in water.

3.         It has sweet taste.

CHEMICAL PROPERTIES:

1.         It chars by dehydration to a black residue of carbon on addition of Conc.  H₂SO₄.

                        C₁₂H₂₂O₁₁                      12C  +  6H₂O

2.         It undergoes hydrolysis to equal quantity of glucose and fructose when boiled with dil.

            H₂SO₄ or HCL (aq)

3.         It undergoes inversion under the influence of invertase in yeast

                        Sucrose                        invertase          Glucose + Fructose

4.         It is non-reducing sugar.

TEST:

Glucose gives a red precipitate with freshly prepared Seliwanoff’s reagent.

USES

1.         For sweetening foods and beverages.

2.         For ethanol production by fermentation.

POLYSACCHARIDES

Polysaccharides are a group of complex carbohydrates composed of very long chains of monosaccharide linked together by condensation polymerization.

            Monosaccharide            ^condensation           polysaccharides  +   n/₂  water

                                                ^Hydrolysis

Some important examples of polysaccharides are starch, glycogen, and cellulose.  The general molecular formula of polysaccharides is (C₆H₁₀O₅)n

EVALUATION

1.         Name three disaccharides and the component monosaccharide.

2.         Describe what would be observed on addition of Conc. H₂SO₄ to sucrose.

PROTEIN

Proteins are made up of polypetides chains.  Polypeptide chains are products of condensation polymerization of amino acid molecules.  The condensation polymerization of amino acid is the interaction between amino groups, -NH₂, and Carboxyl groups, -COOH, to form the polypeptide chain.

A polypeptide chain:

                        H          O                      H          O                     H         

                                                                                                            O

⁺H₃ N    C          C          [N         C          C]  +_nN C         

                                                                                                               O

                        R                        H        R                      H          R 

Amino end                                dipeptide                      Carboxyl end

OCCURRENCE

Proteins are found in living cells where they perform different functions.  Examples are hemoglobin,  collagen and insulin, ribonucleic.  The structure have cross linkage between chains which are called disulphide bridges or disulphide cross linkages.

Properties

1.         They are denatured easily at a temperature above 40⁰C by variation in PH and by certain organic solvents and chemical reagents.

2.         Proteins are hydrolyzed to give amino acids by boiling with dilute acids (e.g. HCI) and alkalis or  using enzymes.

Uses

1.         They are used for building up of tissues and repairing of worn-out tissues in the body.

2.         They are necessary for growth especially in infants.

Tests

1.         Million’s test – A white ppt. is form when a few drops of Million’s reagent are added to some

egg-white in a test-tube.  The white ppt. turns brick red on heating (indicating the presence of proteins).

2.         Biuret test:  when few drops of dilute NaOH solution is added to some egg white solution in

a test tube, and 1% CUSO₄ solution is added drop by drop and the test solution is shaken

vigorously after each drop.  A violet colour is seen indicating a positive test for proteins.

3.         Proteins form an intense yellow colour with a few drops of conc.  HNO₃ acid.

EVALUATION

1.         Explain a chemical test for proteins.

2.         What is the product of hydrolysis of proteins?

AMINO-ACIDS

Amino acids are the basic structural units of proteins.

The functional groups in amino acids are amino group (-NH₂) and a carboxyl group (-COOH)

General structure

NH₂          α carbon

  H        C         COOH

                                                R

EVALUATION

1.         Give the functional group of protein.

2.         Draw the structural formula of a polypeptide.

α carbons are carbons in amino acids to which the functional groups are attached.

Examples – glycine, phenylalnine, alanine etc.  Amino acids are mainly in form of dipolar ions in neutral solution (zwitterions).

EVALUATION

1.         Name the functional groups present in amino acids molecule.

2.         What are proteins?

3.         State two properties of protein.

WEEKEND ASSIGNMENT

1.         One of the following is not a monosaccharide

            A.  glucose       B.  maltose       C.  fructose    D. maltose

2.         The product obtained when sucrose is treated with dil. HCI are

            A.  glucose and galatose    B.  fructose and galatose    C.  glucose and fructose  D. glucose

3.         Which of the following is a reducing sugar?

            A.  fructose       B.  glucose       C.  sucrose           D. ribose

4.         Which one of these substances is not a polysaccaharides?

            A.  lactose        B.  starch          C.  cellulose         D. mannose

5.         Few drops of conc HNO₃ is added to a solution and an intense yellow colour is obtained,

then the solution contained.

            A.  proteins      B.  carbohydrates         C.  fat     D. oil

THEORY

1.         Explain a laboratory test for proteins.

2a.       What are carbohydrates?

• Name the component monosaccaharide of

(i)         sucrose          (ii)     maltose.

READING ASSIGNMENT

New School Chemistry by Y.O Ababio page 520 – 531.

WEEK TEN

TOPIC:AMINES AND AMIDES

CONTENTS:   General molecular formular/structure, preparation, properties and uses.

AMINES:

It has a functional group of NH₂.

GENERAL MOLECULAR FORMULAR/STRUCTURE:

It has a general molecular formula of RNH₂ or structure of              R – N – H

                                                                                                                 H

PREPARATION:

They are derivatives of ammonia where one or more hydrogen atoms have been replaced by alkyl or aryl groups e.g. RNH_z, R₂NH.

CLASSIFICATION:

Amines can be classified according to alkyl group.

1.         Primary amine with one alkyl group e.g. RNH₂ or   

R                      or                     CH₃

            H          N          H                      H          N          H

2.      Secondary amine with 2 alkyl groups e.g. R₂NH or

R                      CH₃

                                    R          N    or     CH₃     N        H

                                                H

3.        Tertiary amine with 3 alkyl groups e.g. R₃N  or

                                       R                                             CH₃

                             R¹     N        R¹¹    or             CH₃        N     CH₃     

                                                            Trimethyl amine

PHYSICAL PROPERTIES

1. They can dissolve in water.

2. They are gases and liquid.

3. They have fishy odour.

CHEMICAL PROPERTIES

1. As bases they neutralize acids.

2. They dissociate/ionize in water e.g. CH₃NH₂ + H₂O  CH₃NH₃⁺+  OH^–

USES

1. Used in making nylon

2. They can also be used in making polyamide.

EVALUATION

1. State two (2)  physical properties and two (2) chemical properties of amine.

2. Give the classes of amine according to the number of their alkyl groups.

AMIDES

                                      O

It has functional group of –C    which is known as carbonamide group.

                                     NH₂

STRUCTURE:

                             O                H        O

            CH₃     C        or     H   C     C

                          NH₂                H    N    H

                                                       H

PREPARATION

–           Amide e.g. ethanmide can be derived from ethanoic acid in the presence of ammonia.

                  O               OOO

CH₃       C       +    NH₃  C     +   H₂O    CH3 – C      + NH₃        CH₃  C          +H₂O

OH                                   NH₂

              OH                    NH₂

– Amide is commonly prepared by reacting esters with concentrated aqueous ammonia.                                             E.gCH₃COOC₂H₅  + NH₃                        Ethanamide CH₃CONH₂ + C₂H₅OH

-They can also be prepared by removing a molecule of water from ammonium salt of carboxylic x acids.

            e.g. CH₃COONH₄               CH₃CONH₂ + H₂O

PHYSICAL PROPERTIES:

1. Only methanamide is a liquid while others are solid.

2. They have high melting point and high boiling point.

CHEMICAL PROPERTIES:

1. Amide can be hydrolysed in the presence of alkali and mineral acid e.g.

CH₃CONH₂  +  H₂O         CH₃COOH + NH₃

2. In the presence of sodium hydroxide and bromine, amides produce amines with elimination of one     carbonyl group.

e.g.CH₃CONH₂  +  Br₂ + 4NaOH           CH₃NH₂ + 2NaBr + Na₂CO₃ + 2H₂O

USES:

1. Used in the preparation of amines.

2. Used in making synthetic resins and plastics.

3. It can also be used in making fertilizer.

CARBAMIDE/UREA

This is an amide of hydrogen trioxo carbonate (IV) acid.  It is produced by compressing CO₂ and NH₃ at high pressure at 200⁰C.

H₂CO₃               CO(NH₂)₂

                        OH                               NH_z

        O     C                              O      C

                OH                           NH_z

                                    Carbonamide/urea

N.B.:     Urea is produced in our body and excreted in the urine.

EVALUATION

1. Write the structural formula of amide.

2. Give one different between amine and amide.

READING ASSIGNMENT

New School Chemistry by O.Y. Ababio pages 520-521

WEEKEND ASSIGNMENT

1.Tertiary amine is represented as follow

      A.  R₂NH₂   B.  (CH₃)₂NH       C.R₂NH₃    D.  R₂N

2.Which of the following has fishy odour

A.  alkanoic acid    B.  alkanol   C.  amide     D.  amine

3.Amide can be regarded as derivatives of …………

A.  alkanol   B.  policarboxylic acid   C.  monocarboxylic acid  D.  carbonxamide group

4.During the hydrolysis of amides, one of the following is produced.

A.  monocarboxylic acids   B.  water    C.  H₂SO₄    D.NaOH

5. Carbamide is an example of

            A.  amine    B.  alkane  C.  alkyl    D.  amide    

THEORY

1(a).     State two (2) physical properties of amide.

  (b).    How would you prepare ethanamide from an ester.

2(a).     State two (2) chemical properties of amide.

  (b).    How would you identify an example of amine in the laboratory.