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SPM CHEMISTRY : Chapter 2 hydrocarbon
SPM CHEMISTRY : Chapter 2 hydrocarbon
SPM CHEMISTRY : Chapter 2 hydrocarbon
SPM CHEMISTRY : Chapter 2 hydrocarbon
SPM CHEMISTRY : Chapter 2 hydrocarbon
SPM CHEMISTRY : Chapter 2 hydrocarbon
SPM CHEMISTRY : Chapter 2 hydrocarbon
SPM CHEMISTRY : Chapter 2 hydrocarbon
SPM CHEMISTRY : Chapter 2 hydrocarbon
SPM CHEMISTRY : Chapter 2 hydrocarbon
SPM CHEMISTRY : Chapter 2 hydrocarbon
SPM CHEMISTRY : Chapter 2 hydrocarbon
SPM CHEMISTRY : Chapter 2 hydrocarbon
SPM CHEMISTRY : Chapter 2 hydrocarbon
SPM CHEMISTRY : Chapter 2 hydrocarbon
SPM CHEMISTRY : Chapter 2 hydrocarbon
SPM CHEMISTRY : Chapter 2 hydrocarbon
SPM CHEMISTRY : Chapter 2 hydrocarbon
SPM CHEMISTRY : Chapter 2 hydrocarbon
SPM CHEMISTRY : Chapter 2 hydrocarbon
SPM CHEMISTRY : Chapter 2 hydrocarbon
SPM CHEMISTRY : Chapter 2 hydrocarbon
SPM CHEMISTRY : Chapter 2 hydrocarbon
SPM CHEMISTRY : Chapter 2 hydrocarbon
SPM CHEMISTRY : Chapter 2 hydrocarbon
SPM CHEMISTRY : Chapter 2 hydrocarbon
SPM CHEMISTRY : Chapter 2 hydrocarbon
SPM CHEMISTRY : Chapter 2 hydrocarbon
SPM CHEMISTRY : Chapter 2 hydrocarbon
SPM CHEMISTRY : Chapter 2 hydrocarbon
SPM CHEMISTRY : Chapter 2 hydrocarbon
SPM CHEMISTRY : Chapter 2 hydrocarbon
SPM CHEMISTRY : Chapter 2 hydrocarbon
SPM CHEMISTRY : Chapter 2 hydrocarbon
SPM CHEMISTRY : Chapter 2 hydrocarbon
SPM CHEMISTRY : Chapter 2 hydrocarbon
SPM CHEMISTRY : Chapter 2 hydrocarbon
SPM CHEMISTRY : Chapter 2 hydrocarbon
SPM CHEMISTRY : Chapter 2 hydrocarbon
SPM CHEMISTRY : Chapter 2 hydrocarbon
SPM CHEMISTRY : Chapter 2 hydrocarbon
SPM CHEMISTRY : Chapter 2 hydrocarbon
SPM CHEMISTRY : Chapter 2 hydrocarbon
SPM CHEMISTRY : Chapter 2 hydrocarbon
SPM CHEMISTRY : Chapter 2 hydrocarbon
SPM CHEMISTRY : Chapter 2 hydrocarbon
SPM CHEMISTRY : Chapter 2 hydrocarbon
SPM CHEMISTRY : Chapter 2 hydrocarbon
SPM CHEMISTRY : Chapter 2 hydrocarbon
SPM CHEMISTRY : Chapter 2 hydrocarbon
SPM CHEMISTRY : Chapter 2 hydrocarbon
SPM CHEMISTRY : Chapter 2 hydrocarbon
SPM CHEMISTRY : Chapter 2 hydrocarbon
SPM CHEMISTRY : Chapter 2 hydrocarbon
SPM CHEMISTRY : Chapter 2 hydrocarbon
SPM CHEMISTRY : Chapter 2 hydrocarbon
SPM CHEMISTRY : Chapter 2 hydrocarbon
SPM CHEMISTRY : Chapter 2 hydrocarbon
SPM CHEMISTRY : Chapter 2 hydrocarbon
SPM CHEMISTRY : Chapter 2 hydrocarbon
SPM CHEMISTRY : Chapter 2 hydrocarbon
SPM CHEMISTRY : Chapter 2 hydrocarbon
SPM CHEMISTRY : Chapter 2 hydrocarbon
SPM CHEMISTRY : Chapter 2 hydrocarbon
SPM CHEMISTRY : Chapter 2 hydrocarbon
SPM CHEMISTRY : Chapter 2 hydrocarbon
SPM CHEMISTRY : Chapter 2 hydrocarbon
SPM CHEMISTRY : Chapter 2 hydrocarbon
SPM CHEMISTRY : Chapter 2 hydrocarbon
SPM CHEMISTRY : Chapter 2 hydrocarbon
SPM CHEMISTRY : Chapter 2 hydrocarbon
SPM CHEMISTRY : Chapter 2 hydrocarbon
SPM CHEMISTRY : Chapter 2 hydrocarbon
SPM CHEMISTRY : Chapter 2 hydrocarbon
SPM CHEMISTRY : Chapter 2 hydrocarbon
SPM CHEMISTRY : Chapter 2 hydrocarbon
SPM CHEMISTRY : Chapter 2 hydrocarbon
SPM CHEMISTRY : Chapter 2 hydrocarbon
SPM CHEMISTRY : Chapter 2 hydrocarbon
SPM CHEMISTRY : Chapter 2 hydrocarbon
SPM CHEMISTRY : Chapter 2 hydrocarbon
SPM CHEMISTRY : Chapter 2 hydrocarbon
SPM CHEMISTRY : Chapter 2 hydrocarbon
SPM CHEMISTRY : Chapter 2 hydrocarbon
SPM CHEMISTRY : Chapter 2 hydrocarbon
SPM CHEMISTRY : Chapter 2 hydrocarbon
SPM CHEMISTRY : Chapter 2 hydrocarbon
SPM CHEMISTRY : Chapter 2 hydrocarbon
SPM CHEMISTRY : Chapter 2 hydrocarbon
SPM CHEMISTRY : Chapter 2 hydrocarbon
SPM CHEMISTRY : Chapter 2 hydrocarbon
SPM CHEMISTRY : Chapter 2 hydrocarbon
SPM CHEMISTRY : Chapter 2 hydrocarbon
SPM CHEMISTRY : Chapter 2 hydrocarbon
SPM CHEMISTRY : Chapter 2 hydrocarbon
SPM CHEMISTRY : Chapter 2 hydrocarbon
SPM CHEMISTRY : Chapter 2 hydrocarbon
SPM CHEMISTRY : Chapter 2 hydrocarbon
SPM CHEMISTRY : Chapter 2 hydrocarbon
SPM CHEMISTRY : Chapter 2 hydrocarbon
SPM CHEMISTRY : Chapter 2 hydrocarbon
SPM CHEMISTRY : Chapter 2 hydrocarbon
SPM CHEMISTRY : Chapter 2 hydrocarbon
SPM CHEMISTRY : Chapter 2 hydrocarbon
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SPM CHEMISTRY : Chapter 2 hydrocarbon

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SPM CHEMISTRY : Chapter 2 Form 5 - Hyrocarbon

SPM CHEMISTRY : Chapter 2 Form 5 - Hyrocarbon

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  • 1. Alkanes 1. General Formula : CnH2n+2 (number of atoms, n = 1,2,3......) 2. They are saturated hydrocarbons; each carbon atom is bonded to four other atoms by single covalent bonds. 3. The members of the family, ending with name ―ane‖. Number of carbon atoms (n) Name Molecular formula CnH2n+2 Molar mass (g mol-1 ) Physical state at room temperatu re 1 Methane C1H2x1+2 = CH4 16 Gas 2 Ethane C2H2x2+2 = C2H6 30 Gas 3 Propane C3H2x3+2 = C3H8 44 Gas 4 Butane C4H2x4+2 = C4H10 58 Gas 5 Pentane C5H2x5+2 = C5H12 72 Liquid 6 Hexane C6H2x6+2 = C6H14 86 Liquid 7 Heptane C7H2x7+2 = C7H16 100 Liquid 8 Octane C8H2x8+2 = C8H18 114 Liquid 9 Nonane C9H2x9+2 = C9H20 128 Liquid 10 Decane C10H2x10+2 = C10H22 142 Liquid Consecutive members different in molar mass is 14 g mol-1 Bright Minds 016-6412016 Thuran Bright Minds
  • 2. 4. Structural formulae of alkanes Name No. of isomers Structural formulae and Name Methane CH4 0 Ethane, C2H6 0 Propane, C3H8 0 Butane, C4H10 2 H H H H │ │ │ │ H ─ C ─ C ─ C ─ C ─ H │ │ │ │ H H H H n-butane H H H │ │ │ H ─ C ─ C ─ C ─ H │ │ │ H H H H │ H ─ C ─ H │ H H H │ │ H ─ C ─ C ─ H │ │ H H Bright Minds 016-6412016 Thuran Bright Minds
  • 3. Pentane, C5H12 3 2 - methyl propane H H H │ │ │ H ─ C ─── C ─── C ─ H │ │ │ H H─C─H H │ H H H H H H │ │ │ │ │ H ─ C ─ C ─ C ─ C ─ C ─ H │ │ │ │ │ H H H H H n-pentane H H H H │ │ │ │ H ─ C ─── C ─── C ─ C ─ H │ │ │ │ H H─C─H H H │ H 2-methyl butane 1 2 3 4 Bright Minds 016-6412016 Thuran Bright Minds
  • 4. Hexane, C6H14 5 H │ H H ─ C ─ H H │ │ │ H ─ C ─── C ─── C ─ H │ │ │ H H─C─H H │ H 2,2-dimetyl propane H H H H H H │ │ │ │ │ │ H ─ C ─ C ─ C ─ C ─ C ─ C ─ H │ │ │ │ │ │ H H H H H H n-hexane H H H H H │ │ │ │ │ H ─ C ─── C ─── C ─ C ─ C ─ H │ │ │ │ │ H H─C─H H H H │ H 2 - methyl pentane Bright Minds 016-6412016 Thuran Bright Minds
  • 5. H │ H H ─ C ─ H H H │ │ │ │ H ─ C ─── C ─── C ─ C ─ H │ │ │ │ H H─C─H H H │ H 2,2 - dimethyl butane 2,3 - dimethyl butane H H H H H │ │ │ │ │ H ─ C ─ C ─── C ─── C ─ C ─ H │ │ │ │ │ H H H─C─H H H │ H 3 - methyl pentane H │ H H H ─C─H H │ │ │ │ H ─ C ─── C ─── C ─── C ─ H │ │ │ │ H H─C─H H H │ H Bright Minds 016-6412016 Thuran Bright Minds
  • 6. Physical Properties Physical properties of alkanes i. cannot conduct electrity ii. less dense than water iii. dissolve in organic solvents, insoluble in water iv. low melting and boiling points Conclusion: - molecule held together by weak intermolecular forces - properties of covalent compound - gradually steady increase as the number of carbon in alkane increases Bright Minds 016-6412016 Thuran Bright Minds
  • 7. 6. Steps to name branched alkanes; i. determined and named the long chains ii. determined and named the branch chain CH3 : methyl C2H5 OR CH2CH3 : ethyl C3H7 OR CH2CH2CH3 : prophyl iii. give number to the carbon atoms in long chain, which started from the nearest branched iv. The number for carbon atom which branched emerged from, must put before/infront the alkyl v. Named the branched first, followed by the named of long chains The word ― di, tri‖ is used if the branched chains is more than one Chemical Properties Pg 38 Reactivity of alkanes 1. Not reactive/unreactive because saturated hydrocarbon 2. Did not decolourized purple solution of acidified potassium manganate(VII) 3. Did not decolourized reddish brown solution of bromin water 4. Neutral. Combustion of alkanes 1. In the presence of sufficient oxygen, alkanes burns to form carbon dioxide and water. – complete combustion Chemical equation: i. CH4 + O2  CO2 + H2O CH4 + 2O2  CO2 + 2H2O Bright Minds 016-6412016 Thuran Bright Minds
  • 8. ii. C2H6 + 7/2 O2  2CO2 + 3H2O iii. C4H10 + 13/2 O2  4CO2 + 5H2O iv. C6H14 + 19/2 O2  6CO2 + 7H2O Answers i. CH4 + 2O2  CO2 + 2H2O ii. C2H6 + 7 O2  2CO2 + 3H2O 2 2 x C2H6 + 2 x 7 O2  2x 2CO2 + 2x 3H2O 2 2C2H6 + 7 O2  4CO2 + 6H2O Bright Minds 016-6412016 Thuran Bright Minds
  • 9. iii. C4H10 + 13/2 O2  4CO2 + 5H2O iv. C6H14 + 19/2 O2  6CO2 + 7H2O 2. If there is insufficient oxygen, carbon monoxide or carbon may be formed – incomplete combustion i. CH4 + 3/2 O2  CO + 2H2O 2CH4 + 3 O2  2CO + 4H2O ii. CH4 + O2  C + 2H2O Bright Minds 016-6412016 Thuran Bright Minds
  • 10. Halogenation 1. The reaction is between alkane dan chlorine. 2. Takes place under sunlight/ultra violet light. 3. Carbon-hydrogen bonds broken and new carbon-halogen bonds are formed. One or more hydrogen atoms in alkanes molecule may be subtituted by halogen. 4. Halogenation is substitution reaction. Chlorination of methane First stage; Second stage; H H │ | H ─ C ─ H +Cl-Cl → H — C — Cl + HCl │ | H H monochloromethane H Cl │ | H ─ C ─ Cl + Cl2 → H — C — Cl + HCl │ | H H dichloromethane Third stage ; Fourth stage; Cl Cl │ | H ─ C ─ Cl + Cl2 → H — C — Cl + HCl │ | H Cl trichloromethane Cl Cl │ | H ─ C ─ Cl + Cl2 → Cl — C — Cl + HCl │ | Cl Cl tetrachloromethane Bright Minds 016-6412016 Thuran Bright Minds
  • 11. Alkenes 1. General formulae : CnH2n [ no alkene corresponding to n = 1 as CH2 is not exist] 2. Alkenes is unsaturated hydrocarbon because the presence of the double bond. 3. Name of each members end with “ene”. No. of carbon atom Name Molecular formulae Molar mass / g mol-1 Physical state at room condition 1 None 2 Ethene C2H4 28 Gas 3 Propene C3H6 42 Gas 4 Butene C4H8 56 Gas ethenes Alkenes containing at least one carbon-carbon double bond Bright Minds 016-6412016 Thuran Bright Minds
  • 12. 5 Pentene C5H10 70 Liquid 6 Liquid 7 Liquid 8 Liquid 9 Liquid 10 Liquid WHEN THE NUMBER OF CARBON IN HYDROCARBON INCREASES/GREATER/HIGHER, THE SIZE OF HC MOLECULE IS BIGGER. THUS, THE INTERMOLECULAR FORCES/Van der Waals FORCES IS STRONGER. THUS, MORE ENERGY IS NEEDED TO OVERCOME THE FORCES. 4. Structure formula for few members of alkenes Name Number of isomer Structure formula and name Ethene C2H4 0 H H │ │ C ═ C │ │ H H Bright Minds 016-6412016 Thuran Bright Minds
  • 13. Propene C3H6 0 H H │ │ C ═ C ─ C ─ H │ │ │ H H H Bright Minds 016-6412016 Thuran Bright Minds
  • 14. Butene, C4H8 3 H H │ │ H ─ C ─ C ═ C ─ C ─ H │ │ │ │ H H H H H H │ │ C ═══ C ─── C ─ H │ │ │ H H─C─H H │ H but -2- ene 2-methyl propene H H H │ │ │ C ═ C ─ C ─ C ─ H │ │ │ │ H H H H but -1- ene Bright Minds 016-6412016 Thuran Bright Minds
  • 15. Pentene, C5H10 5 H H H │ │ │ C ═══ C ─── C ─ C ─ H │ │ │ │ H H─C─H H H │ H 2-methylbut -1- ene H H H │ │ │ H ─ C ─ C ─ C ═ C ─ C ─ H │ │ │ │ │ H H H H H H H H H │ │ │ │ C ═ C ─ C ─ C ─ C ─ H │ │ │ │ │ H H H H H pent -1- ene pent -2- ene H H H H │ │ │ │ C ═ C ─── C ─── C ─ H │ │ │ H H─C─H H │ H 3-methyl but -1- ene Bright Minds 016-6412016 Thuran Bright Minds
  • 16. Hexene, C6H12 12 H H H │ │ │ H─ C ─── C ═══ C ─C ─ H │ │ │ H H─C─H H │ H 2-methyl but -2- ene H H H H H │ │ │ │ │ C ═ C ─ C ─ C ─ C ─ C ─ H │ │ │ │ │ │ H H H H H H H H H H │ │ │ │ H ─ C ─ C ═ C ─ C ─ C ─ C ─ H │ │ │ │ │ │ H H H H H H H H H H │ │ │ │ H ─ C ─ C ─ C ═ C ─ C ─ C ─ H │ │ │ │ │ │ H H H H H H Bright Minds 016-6412016 Thuran Bright Minds
  • 17. H H H H │ │ │ │ C ═══ C ─── C ─ C ─ C ─ H │ │ │ │ │ H H─C─H H H H │ H H H H H │ │ │ │ C ═ C ─── C ─── C ─ C ─ H │ │ │ │ │ H H H─C─H H H │ H H H H H │ │ │ │ C ═ C ─ C ─── C ─── C ─ H │ │ │ │ │ H H H H─C─H H │ H Bright Minds 016-6412016 Thuran Bright Minds
  • 18. H H H H │ │ │ │ H ─ C ─── C ═══ C ─ C ─ C ─ H │ │ │ │ H H─C─H H H │ H H H H │ │ │ H ─ C ─ C ═══ C ─── C ─ C ─ H │ │ │ │ │ H H H─C─H H H │ H H H H │ │ │ H─C ─ C ═ C ─── C ─── C ─ H │ │ │ │ │ H H H H─C─H H │ H Bright Minds 016-6412016 Thuran Bright Minds
  • 19. H │ H H─C─H H │ │ │ C ═══ C ─── C ─── C ─ H │ │ │ │ H H─C─H H H │ H H │ H H─C─H H │ │ │ H─ C ─── C ═══ C ─── C ─ H │ │ │ H H─C─H H │ H H │ H H─C─H H │ │ │ C ═══ C ─── C ─── C ─ H │ │ │ │ H H H─C─H H │ H Bright Minds 016-6412016 Thuran Bright Minds
  • 20. Can you named the molecules? Steps to name branched alkenes; i. determined and named the long chains that has double covalent bond ii. numbered the carbon atom from the nearest end to double covalent bond iii. determined and named the branch chain CH3 : methyl C2H5 or CH2CH3 : ethyl C3H7 or CH2CH2CH3 : prophyl iii. give number to branched chain iv. The number for carbon atom which branched emerged from, must put before/infront the alkyl v. The word “ di, tri” is used if the branched chains is more than one Bright Minds 016-6412016 Thuran Bright Minds
  • 21. Physical Properties Physical properties of alkenes (similar to alkanes) i. cannot conduct electrity ii. less dense than water iii. obeys “ like dissolve like”;  dissolve in organic solvents  insoluble in water iv. low melting and boiling points, gradually steady increase as the number of carbon in alkene increases Bright Minds 016-6412016 Thuran Bright Minds
  • 22. Chemical Properties Reactivity of alkenes 1. Alkenes is more reactive because the presence of double covalent bond, (unsaturated hydrocarbon) 2. Alkenes decolourized purple solution of acidified potassium manganate(VII) 3. Alkenes decolourized reddish brown solution of bromin water 4. Neutral. Combustion of alkenes . Bright Minds 016-6412016 Thuran Bright Minds
  • 23. Addition Reaction (5.2) The carbon-carbon double bond is converted into two single bonds H H H H     C = C + X  Y  X  C  C  Y     H H H H Alkenes Molecule Alkanes (Unsaturated) (Saturated) Bright Minds 016-6412016 Thuran Bright Minds
  • 24. 1. Addition of hydrogen Mixture of alkenes gas/vapour and hydrogen gas, is passed through platinum or nickel at 180 o C. The process is known as catalytic Hydrogenation. Catalyst: platinum or nickel H H H H   Ni/Pt   C = C + H2  H C  C H   180o C   H H H H Ethene Hydrogen Ethane Chemical equation: C2H4 + H2  C2H6 Example use of this process: Manufacture of margarine is through hydrogenation Bright Minds 016-6412016 Thuran Bright Minds
  • 25. 2. Addition of halogens The process is known as halogenation H H H H     C = C + Br  Br  Br  C  C  Br     H H H H Ethenes Bromine 1,2-dibromoethanes (unsaturated) (saturated) Chemical equation: C2H4 + Br2  C2H4Br2 [HW-notes book] Q1: Write a chemical equation reaction between but-1-ene with bromine water. Show the structural formula as well. [HW-exercises book] Q2: Halogenation process is best used to differentiate between alkanes and alkenes. Explain how it can be done? [notes: refer to SAB] Bright Minds 016-6412016 Thuran Bright Minds
  • 26. 3. Addition of hydrogen halides i. Alkenes reacts with hydrogen halide in room condition. Hydrogen halide molecules is added to double bond in alkenes, to produce halogenoalkane. ii. When hydrogen chloride gas is passed through into ethenes, monochloroethanes is produced. H H H H     C = C + H─Cl  H C  C Cl     H H H H Ethenes Hydrogen chloride Monochloroethanes (Unsaturated) (Saturated) Chemical equation: C2H4 + HCl → C2H5Cl Bright Minds 016-6412016 Thuran Bright Minds
  • 27. 4. Addition of acidified potassium manganate(VII) 1. When alkenes is mixed with acidified potassium manganate(VII), its purple colour is decolourised. 2. This is because addition process occurred, a group of hydroxyl (--OH) is added to the molecules of alkenes to form a molecule of –diol (type of alcohol) which is saturated and colourless.     C = C + H2O   C  C      OH OH Alkenes alkanes-diol compound (Unsaturated) (Saturated) [O] [from acidified KMnO4] Bright Minds 016-6412016 Thuran Bright Minds
  • 28. Example; H H H H     C = C + H2O + [O]  H  C  C H     H H OH OH Ethene Ethane-1,2-diol (Unsaturated) (Saturated) Q: Use propene as example. H H H H H     │ H— C —C = C + H2O + [O]  H  C−C  C H │   │   H H H H OH OH Propene, C3H6 Propane-1,2-diol C3H6 + H2O + [O]  C3H8O2 Bright Minds 016-6412016 Thuran Bright Minds
  • 29. 5. Steam (Hydration process) 1. Alkenes react with steam to produce equivalent alcohol at the temperature of 300 o C and in the pressure of 60 atmosphere. 2. Reactions catalyst by concentrated phosphoric acid, H3PO4. 3. This method is one of the industrial preparation to produce alcohol. H H H H     C = C + H─OH  H C  C  H     H H H OH Ethene Steam Ethanol C2H4 + H2O → C2H5OH @ C2H6O Q: Use but-1-ene C4H8 + H2O  C4H9OH / C4H10O 300 o C, 60 atm H3PO4 300 o C, 60 atm H3PO4 Bright Minds 016-6412016 Thuran Bright Minds
  • 30. Polymerization 5.3 Polymer :Large molecules made up from many identical repeating sub-units called monomers, which joined together by covalent bond. Polymerization is a process of repeated linking when a monomers are joined into chains Reaction to form a polymer from alkene monomers is called an addition polymerisation Bright Minds 016-6412016 Thuran Bright Minds
  • 31. Homologous Series Characteristic of Homologous Series Bright Minds 016-6412016 Thuran Bright Minds
  • 32. Bright Minds 016-6412016 Thuran Bright Minds
  • 33. 1 Comparing properties of Alkanes and Alkenes Similarities: Properties Alkanes & Alkenes Solubility in water No Solubility in organic solvent Yes Conductivity No Boiling and melting point Low Molecular formula Each member of homologous differs from the next/successive member by a unit −CH2− Molecular mass Each member of homologous differs from the next/successive member of 14 unit Differences: Properties Alkanes Alkenes Reaction with oxygen, O2 gas It burned with less sooty yellow flame It burned with a more sooty yellow flame Reaction with bromine, Br2 water The reddish-brown colour of bromine water remains unchanged The reddish- brown colour of bromine water decolourised Reaction with acidified potassium manganate(VII), KMnO4 solution The purple colour of acidified potassium manganate(VII) solutions remained unchanged The purple colour of acidified potassium manganate(VII) solutions was decolourised Bright Minds 016-6412016 Thuran Bright Minds
  • 34. 2 ESSAY; HOW TO DIFFERENTIATE THE ALKANE and ALKENE IN THE BOTTLES? Solutions: i. Procedure ii. Observations iii. Inference [8marks] Sample answer Aim: To investigate the liquid in bottle A and B Test tube A Test tube B Dropper Test tube BA Bright Minds 016-6412016 Thuran Bright Minds
  • 35. 3 Procedure; 1. The apparatus shown above is prepared. 2. 2-5 cm3 bromine water is measured with measuring cylinder 5ml and poured into a test tube. 3. A few drops of liquid from bottle A is put/added with dropper into the test tube, and shake. 4. Obsevation is recorded. 5. The experiments is repeated by replace the liquid from bottle A with bottle B. Observation: Test Tube Observation Inference Liquid in bottle A The reddish-brown colour of bromine water remains unchanged Contains alkane Liquid in bottle B The reddish-brown colour of bromine water decolourised Contains alkene Bright Minds 016-6412016 Thuran Bright Minds
  • 36. 1 ALCOHOL The Alcohol Family 1. One of member of homologous series which contain carbon, hydrogen and oxygen. 2. General formula for alcohol is CnH2n+1OH. [n=1,2,3..] 3. Alcohol contains the hydroxyl group, -OH as their functional group. [notes: not hydroxide ion, OH- , alcohol not is alkaly ] 4. Alcohol is neutral compound. 5. Alcohol are named by replacing -e for alkane with –ol. Bright Minds 016-6412016 Thuran Bright Minds
  • 37. 2 6. Structural formula and molecule for few alcohol. n Name Mr Molekul Formula Structural formula 1 Methanol 12+3+ 16+1 = 32 CH3OH @ CH4O H | H— C — OH | H 2 Ethanol very important 12x2 + 5 +16 + 1 = 46 C2H5OH @ C2H6O H H | | H— C — C — OH | | H H 3 Propan-1- ol 60 C3H7OH H H H | | | H — C— C — C — OH | | | H H H 4 Butan-1- ol 74 C4H9OH 5 Pentan-1- ol 88 C5H11OH 6 Hexan-1- ol 102 C6H13OH Bright Minds 016-6412016 Thuran Bright Minds
  • 38. 3 Q: Give names for this alcohol. OH  CH3  CH2  CH  CH2  CH2  CH3 Formula: C6H13OH Name : HEXAN-3-OL Bright Minds 016-6412016 Thuran Bright Minds
  • 39. 4 Naming Alcohol 1. Find the longest continous carbon chain containing –OH. 2. Number the carbon beginning at the end nearer to the – OH, write the number in front of the ending –ol. 3. Locate the alkyl group (branch chain), give number to the carbon and named the alkyl group. Put the number in front of the group.  CH3 : methyl  C2H5 atau CH2CH3 : ethyl  C3H7 atau CH2CH2CH3 : propyl 4. Complete the name for the alcohol (ii) OH  CH3  CH2  C  CH2  CH2  CH3 | CH3 Formula: C7H15OH Name : 3-methyl hexan-3-ol Bright Minds 016-6412016 Thuran Bright Minds
  • 40. 5 (iii) OH  CH3  CH2  CH  CH  CH2  CH3 | CH3 Formula : C7H15OH Name : 4-methyl hexan-3-ol (iii) OH  CH3  CH  CH  CH  CH2  CH2 | | | CH3 CH3 CH3 Formula : C9H19OH Name : 2, 4 – dimethyl heptan-3-ol Bright Minds 016-6412016 Thuran Bright Minds
  • 41. 6 (iv) C2H5 OH   CH3  CH2  CH  CH2  CH  CH2 ─ CH3 Formula : C9H19OH Name : 5-ethyl heptan-3-ol Physical Properties 1. Liquid at room temperature. (pg. 62) [ no gas] 2. Simple alcohol are very soluble in water, infinite solubility. Methanol, ethanol dan propan-1-ol is miscible in all proportions (terlarut campur dengan air dalam semua kadaran). The rest of the alcohol less soluble or insoluble. Isomerism Similar to alkenes, isomerism in alcohol results from the branching of the carbon chain and the different location of the hydroxyl group. You only have to know the isomerism in propanol dan butanol. Q : Draw 2 isomers for propanol and 4 isomers for butanol, and dan named the isomers. Bright Minds 016-6412016 Thuran Bright Minds
  • 42. 7 Propanol Butanol Bright Minds 016-6412016 Thuran Bright Minds
  • 43. 8 Propanol H H H │ │ │ H ─ C ─ C ─ C ─ OH │ │ │ H H H H H H │ │ │ H ─ C ─ C ─ C ─ H │ │ │ H OH H Molecular formula: C3H7OH Name: Propan-1-ol Molecular formula: C3H7OH Name: Propan-2-ol Bright Minds 016-6412016 Thuran Bright Minds
  • 44. 9 Butanol Molecular formula: C4H9OH Name: Butan-1-ol Molecular formula: C4H9OH Name: Butan-2-ol H H H H │ │ │ │ H ─ C ─ C ─ C ─ C ─ OH │ │ │ │ H H H H H H H H │ │ │ │ H ─ C ─ C ─ C ─ C ─ H │ │ │ │ H H OH H H H H │ │ │ H ─ C ─── C ─── C ─ OH │ │ │ H H─C─H H │ H Molecular formula: C4H9OH Name: 2-methylpropan-1-ol H OH H │ │ │ H ─ C ─── C ─── C ─ H │ │ │ H H─C─H H │ H Molecular formula: C4H9OH Name: 2-methylpropan-2-ol Bright Minds 016-6412016 Thuran Bright Minds
  • 45. 10 ETHANOL 1. Preparation of ethanol. i. Laboratory preparation (fermentation) ii. Industrial production (hydration process) Making Ethanol Fermentation 1. Two stages; i. Fermentation ii. Purification - through fractional distillation at 78 o C ( boiling point of ETHANOL) Fermentation of Glucose 1. Yeast is added to sugar or starch. 2. Anaerobic process ( takes place in the absence of oxygen). 3. Yeast releases enzymes. These enzymes break down the sugars/starch into glucose, C6H12O6. 4. Zymase slowly decomposes the glucose to form ethanol and carbon dioxide. Zymase @ C2H5OH @ C2H6O C6H12O6 (aq)  2CH3CH2OH (l) + 2CO2 (g) 30 o C Bright Minds 016-6412016 Thuran Bright Minds
  • 46. 11 When the concentration of ethanol reach 15%, the yeast dies. Q: How to produce pure alcohol? A: Purified the ethanol through fractional distillation. Purification of Ethanol 1. Ethanol produced from the fermentation process is impure, because its mix with the glucose solution. Q : Draw labeled diagram to carry out the purification of ethanol through fractional distillation process. Delivery tube Lime water Beaker Glucose + yeast Conical flask Bright Minds 016-6412016 Thuran Bright Minds
  • 47. 12 Q: Why the solution/filtrate in rounded conical must heated at 78o C. A: The boiling point of ethanol is 78 o C. Q: Ethanol produced may still contains of some water. What should be done to be sure that ethanol is 100% pure? A: Anhydrous calcium oxide or anhydrous calcium chloride is add/put into the ethanol. ● ○ XXXXXXXXXXXXXXX Thermometer Fractioning collum Liebig condenser Water in Water out Product from fermentation Porcelain chips Retort stand with clamp Distillate (Ethanol) Bunsen burner Rounded conical Water Wire gauge Bright Minds 016-6412016 Thuran Bright Minds
  • 48. 13 Q: What is the function of; - thermometer - porcelain chips - Liebig condenser A: thermometer is used to ensure that temperature is always at 78 o C. B: Porcelain chips is used to avoid the solution jumped/ effervesence (breaking bubbles) C: To cooled the ethanol vapour to become liquid. Q: Named the process in Liebig condenser. A: Condensation Q: What is the properties of ethanol A: Properties; - colourless - volatile - good organic solvent - miscible with water - highly flammable - antiseptic - chemically reactive Bright Minds 016-6412016 Thuran Bright Minds
  • 49. 14 Q: What is the uses of ethanol A: Uses; - As a solvent in perfumes/cosmetics - As a thinner in varnish, ink - As a cleaner for compact disc. - As a fuel for transport - As a raw material for the manufacture of vinegar, - As a raw material to make industrial product such as antiseptic and cough syrup. Industrial production of ethanol Ethene is mix with steam is passed through concentrated phosphoric acid (catalyst) at 300 o C (temperature) and 60 atmosphere (pressure). H3PO4 @ C2H4 concentrsted C2H5OH CH2 = CH2 + H2O —————→ CH3CH2OH 300 o C, 60 atm Bright Minds 016-6412016 Thuran Bright Minds
  • 50. 15 Chemical Properties 1. Combustion i. Alcohol are very flammable sustances. ii. Ethanol burns with non-smoky and blue flame and releases lot of heat. Suitable for use as fuel, described as clean fuel. Q: Write combustion equation for hexanol 2. Oxidation i. Ethanol can be oxidised into ethanoic acid by an oxidising agent. [Ethanoic acid is a family of carboxilic acids] C2H5OH + 3O2  2CO2 + 3H2O Ethanol Oxygen Carbon Water dioxide C6H13OH + 9O2  6CO2 + 7H2O hexanol Oxygen Carbon Water dioxide CH3CH2OH + 2[O]  CH3COOH + H2O Etanol Ethanoic acid Bright Minds 016-6412016 Thuran Bright Minds
  • 51. 16 Q: Show the structural formula for the equation above. Q: Named 2 solutions are commonly used as oxidising agent. (i) Acidified potassium manganate(VII), KMnO4 (purple to colourless / decolourised) (ii) Acidified potassium dichromate(VI), K2Cr2O7 (orange to green) Q: Draw a labeled diagram for the process. H H H O | | | ║ H — C — C — OH + 2[O] → H — C — C — OH + H2O | | | H H H Heat Ethanol + potassium dikromat(VI) + dilute sulfuric acid Cold water Distillate (ethanoic acid) Bright Minds 016-6412016 Thuran Bright Minds
  • 52. 17 Distillate (ethanoic acid) - Colourless - Vinegar smell - Blue litmus paper turns red (acidic properties) 3. Dehydration ALCOHOL → ALKENE 1. Converted ethanol into ethene and a molecule of water. 2. The elimination of water results the formation of a carbon-carbon double bond. 3. Dehydration occur when a. ethanol vapours is passed over a heated catalyst such as. i- Porous pot / porcelain chips ii- Purnice stone / aluminium oxide, Al2O3 /alumina b. Ethanol is heated under reflux at 170 o C with excess concentrated sulphuric acid. CH3CH2OH  CH2 = CH2 + H2O Ethanol Ethene - H2O Bright Minds 016-6412016 Thuran Bright Minds
  • 53. 18 Q : Draw the structural molecule for the process Q : Draw labeled diagram. Heat Glass wool soaked with ethanol Heat Ethene gas Water Porcelain chips Retort stand with clamp Test tube Delivery tube H H H H | | | | H — C — C — H → H — C ═ C — H + H2O | | H OH Bright Minds 016-6412016 Thuran Bright Minds
  • 54. 1 CARBOXILIC ACID General formula CnH2n+1COOH One hydrogen atom is replaced with functional group – COOH H O | ║ H — C — C — OH | H Formula: HCOOH O ║ H — C — OH Formula: CH3COOH CARBOXYL GROUP Bright Minds 016-6412016 Thuran Bright Minds
  • 55. 2 Why families known as carboxylic ‘acid’ Carboxyl group plays a vital role to gives acidic properties to carboxilic acid families. CH3COOH H+ + CH3COO- Ethanoic acid Hydrogen ion Ethanoate ion Bright Minds 016-6412016 Thuran Bright Minds
  • 56. 3 Molecular and Structural Formula n Name Molecular formula Mr Structural formula 0 Methanoic acid C0H2(0)+1COOH = HCOOH 46 O ║ H — C — OH 1 Ethanoic acid C1H2(1)+1COOH = CH3COOH [C2H4O2] 60 H O | ║ H — C — C — OH | H 2 Propanoic acid C2H2(2)+1COOH = C2H5COOH 74 H H O | | ║ H — C — C — C — OH | | H H 3 Butanoic acid Bright Minds 016-6412016 Thuran Bright Minds
  • 57. 4 Naming carboxilic acids Example 1: C C COOHH H H H C Longest continuous chains: propanoic acid HH H Attached alkyl group: 2-methyl Carboxyl carbon: carbon number 1 Name: 2-methylpropanoic acid C4H8O2 / C3H7COOH C C C O O H H H H H Carbon number 123 Bright Minds 016-6412016 Thuran Bright Minds
  • 58. 5 Example 2: CH3 C COOH H C2H5 Longest continuous chains: butanoic acid Carboxyl carbon: carbon number 1 Name: 2-methylbutanoic acid Attached alkyl group: 2-methyl Bright Minds 016-6412016 Thuran Bright Minds
  • 59. 6 Example 3: Example 4: C3H7 C COOH H C2H5 Name: 2-ethyl pentanoic acid C2H5 C COOH H C3H7 Name: 2-ethyl pentanoic acid Bright Minds 016-6412016 Thuran Bright Minds
  • 60. 7 Ethanoic Asid Can be prepared through oxidation of an ethanol. Chemical equation: This is carried out by refluxing ethanol with an oxidising agent such as acidified potassium dichromate(VI) or potassium manganate(VII) solution. H H │ │ H — C — C — OH │ │ H H H O │ ║ H — C — C — OH │ H + 2[O] + H2O K2Cr2O7 solutions + dilute H2SO4 reflux CH3CH2OH + 2[O]  CH3COOH + H2O Etanol ethanoic acid Bright Minds 016-6412016 Thuran Bright Minds
  • 61. 8 Preparation of ethanoic acid through refluxing Condenser is used to prevent the loss of a volatile liquid by vaporisation. This method of retaining a volatile liquid during heating is called refluxing. How to carry out the activity? Tissel tube Water out xxxxxxxxxxxxxx Label the diagram please Water in Liebig condenser Rounded bottom flask Retort stand Absolute ethanol, C2H5OH + Acidified potassium dichromate(VI), K2Cr2O7 solution Heat Wire gauge Bright Minds 016-6412016 Thuran Bright Minds
  • 62. 9 Physical Properties - pH less than 7 - sharp or unpleasant smell - turn moist blue litmus paper to red - colourless liquid Chemical Properties Acid Properties - Only hydrogen atom in the carboxyl group, [-COOH] can ionize in water to produce hydrogen ions, H+ . Ethanoic acid is a weak acid. Why? - it dissociates in water partially, most of the molecules remain unchanged. CH3COOH CH3COO- + H+ CH3COO- Ethanoic acid Hydrogen ion Ethanoate ion Bright Minds 016-6412016 Thuran Bright Minds
  • 63. 10 Reactions with metals - Dilute ethanoic acid reacts with reactive metal (Zn, Mg, Al) to produce a salt and hydrogen gas. 2CH3COOH + Mg  Mg(CH3COO)2 + H2 Ethanoic acid Magnesium ethanoate 2CH3COOH + Zn  Zn(CH3COO)2 + H2 Ethanoic acid Zink ethanoate 6CH3COOH + 2Al  2Al(CH3COO)3 + 3H2 Ethanoic acid Aluminium ethanoate Bright Minds 016-6412016 Thuran Bright Minds
  • 64. 11 Reactions with bases - Dilute ethanoic acid neutralizes alkalis such as sodium hydroxide solution to give an organic salt and water. - Black copper(II) oxide powder dissolves in dilute ethanoic acid. CH3COOH + NaOH  CH3COONa + H2O Ethanoic acid Sodium ethanoate 2CH3COOH + CuO  Cu(CH3COO)2 + H2O Ethanoic acid Copper(II) ethanoate Bright Minds 016-6412016 Thuran Bright Minds
  • 65. 12 Reactions with carbonates - Dilute ethanoic acid reacts with metal carbonates to produce a salt, carbon dioxide and water. 2CH3COOH + CaCO3  Ca(CH3COO)2 + CO2 + H2O Ethanoic acid Calcium ethanoate 2CH3COOH + Na2CO3  2CH3COONa + CO2 + H2O Ethanoic acid Sodium ethanoate Bright Minds 016-6412016 Thuran Bright Minds
  • 66. 13 Reactions with alcohols [Esterification] Esterification: Carboxilic acid reacts with alcohol to produce an ester and water. Concentrated H2SO4 : catalyst [will discuss more in next chapter] Concentrated H2SO4 Carboxilic acid + Alcohol ——— Ester + Water Bright Minds 016-6412016 Thuran Bright Minds
  • 67. 14 Uses of carboxilic acid: i. Ethanoic acid is known as acetic acids use in; - Food flavoring - Food preservatives - To make drugs, dyes, paints insectisides, plastics - To make esters for use as slovents ii. Methanoic acid is used to coagulate latex. iii. Benzoic acids is used as food preservatives iv. Fatty acids used in making soaps v. Carboxilic acids use in the manufactured of polyester and polyamids (fibres) in textile Bright Minds 016-6412016 Thuran Bright Minds
  • 68. 15 Conclusion on chemical reaction; Carboxilic acid + reactive metal  carboxylate salt + hydrogen Carboxilic acid + base  carboxylate salt + water Carboxylate acid + metal carbonate  carboxylate salt + carbon dioxide + Water Carboxilic acid + alcohol  ester + water 1. Learning task 2.9 Summarizing pg 75 [notes book] 2. Effective Practise pg 75 1, 2, 3 [exercise book] Bright Minds 016-6412016 Thuran Bright Minds
  • 69. 16 ESTER General formula CnH2n+1COOCmH2m+1 R : alkyl group in carboxilic acid R’ : alkyl group in alcohol O ║ CnH2n + 1C — OH + CmH2m+1OH (carboxilic acid) (alcohol) O ║ CnH2n + 1C — O — CmH2m+1 + H2O (ESTER) Bright Minds 016-6412016 Thuran Bright Minds
  • 70. 17 Esterification - Carboxilic acid reacts with alcohol to produce ester and water. - The functional group of ester is carboxilate group. - Concetrated sulphuric acid is catalyst. - Carboxilic acid losses ‘OH’ and - Alcohol losses ‘H’ - The bond that ‘break up’ will ‘rejoin’ again CnH2n + 1 — C O O CmH2m+1 Break up and rejoin Carboxilate group, -COO- Derived from carboxilic acid Derived from alcohol Bright Minds 016-6412016 Thuran Bright Minds
  • 71. 18 Naming Ester - Name of ester consists of two parts, the name of alcohol part is given first and followed by the acid part. Example: i. Ethanoic acid + methanol  methyl ethanoate + water Chemical equation: H O | ║ H — C — C — OH | H CH3COOH (Etanoic acid) H | H— C — OH | H CH3OH (Methanol) + H O H | ║ | H — C — C — O — C — H + H2O | | H H CH3COOCH3 (Methyl ethanoat) Water CH3COOH + CH3OH → CH3COOCH3 + H2O Bright Minds 016-6412016 Thuran Bright Minds
  • 72. 19 Example: ii. Ethanoic acid + ethanol  ethyl ethanoate + water Chemical equation: H O | ║ H — C — C — OH | H Ethanoic acid H H | | H— C — C — OH | | H H Ethanol + H O H H | ║ | | H — C — C — O — C — C — H + H2O | | | H H H ethyl etanoat Water CH3COOH + CH3CH2OH → CH3COOCH2CH3 + H2O Bright Minds 016-6412016 Thuran Bright Minds
  • 73. 20 Example: iii. Methanoic acid + Ethanol  ethyl methanoate + water Chemical equation: O ║ H — C — OH Methanoic acid H H | | H— C — C — OH | | H H Ethanol + O H H ║ | | H — C — O — C — C — H + H2O | | H H Ethyl metanoat Air HCOOH + CH3CH2OH → HCOOCH2CH3 + H2O Bright Minds 016-6412016 Thuran Bright Minds
  • 74. 21 Q: Draw structural molecule of i. Methyl metanoate ii. Pentyl propanoate iii. Propyl ethanoate Solutions; i. Methyl metanoate Methyl methanoate H | H— C — OH | H O ║ H — C — OH MethanolMethanoic acid Break up and rejoin From alcoholFrom carboxilic acid O H ║ | H — C — O — C — H + H2O | H methyl metanoate Air Bright Minds 016-6412016 Thuran Bright Minds
  • 75. 22 ii. Pentyl propanoate Try now Bright Minds 016-6412016 Thuran Bright Minds
  • 76. 23 Prophyl ethanoate H H H | | | H— C — C —C — OH | | | H H H H O | ║ H — C —C — OH | H PropanolEthanoic acid Break up and rejoin From alcoholFrom carboxilic acid H O H H H | ║ | | | H — C — C — O — C — C —C — H + H2O | | | | H H H H propyl ethanoate Water Bright Minds 016-6412016 Thuran Bright Minds
  • 77. 24 Preparation of ester through reflux How to carry out this process? [Success pg 378] After boiling, Liebig condenser is rearranged To carry out the fractional distillation at 74o C – 78o C to collect ethyl ethanoate. XXXXXXXXXXXXXXX Tissel tube Liebig condenser Ethanol + ethanoic acid + concentrated sulphuric acid Porcelain chip Water bath Water in Water out To prevent bumping and ensure smooth boiling To cold the ethanol and ethanoic acid Uniform heating Bright Minds 016-6412016 Thuran Bright Minds
  • 78. 25 Physical properties of ethyl ethanoate - colourless - fragrant smell - insoluble in water - lese dense in water Natural Sources - Most simple esters are found in fruits and flowers. ex: benzyl ethanoate in Jasmine ethyl butanoate in pineapple - Palm oil are liquid ester. - The higher and complex ester does not produce pleasant smells Bright Minds 016-6412016 Thuran Bright Minds
  • 79. 26 Uses of ester - to make perfume, cosmetics - to make artificial food flavoring [Text Book: Table 2.8 pg 81] - used as organic solvents eg. ethyl ethanoate used in sunburn lotion, polish removers, glues. - to make synthetic polymers/fabrics - to make aspirin (pain reliever) Bright Minds 016-6412016 Thuran Bright Minds
  • 80. 1 FATS Fats and oils are chemically similar, but differ in physical states. Bright Minds 016-6412016 Thuran Bright Minds
  • 81. 2 Fats : - found in animals - solid in room temperature - butter and tallow (types of fat) Oil : - fats from plants - liquid in room temperature - palm oil, coconut oil, sunflower oil - Fats and oil are mixtures of different esters. - Fats are formed from 3 molecules of long- chain carboxylic acids called fatty acids with 1 molecules of alcohol called glycerol. Bright Minds 016-6412016 Thuran Bright Minds
  • 82. 3 H │ H ― C ― OH │ H ― C ― OH │ H ― C ― OH │ H Fatty acids - R1 , R2 , R3 contains 12 to 18 carbon atoms per molecule - R1 , R2 , R3 are three alkyl groups which may be the same or different - group: carboxilic acid O ║ OH ― C ― R1 O ║ OH ― C ― R2 O ║ OH ― C ― R3 Glycerol - propane-1,2,3-triol - group: alcohol Bright Minds 016-6412016 Thuran Bright Minds
  • 83. 4 Formation of a fat molecule H │ H ― C ― OH │ H ― C ― OH │ H ― C ― OH │ H O ║ OH ― C ― R1 O ║ OH ― C ― R2 O ║ OH ― C ― R3 H O │ ║ H ― C ― O ― C ― R1 │ │ O │ ║ H ― C ― O ― C ― R2 │ │ O │ ║ H ― C ― O ― C ― R3 │ H + 3H2O + Break up and rejoin Break up and rejoin Break up and rejoin Bright Minds 016-6412016 Thuran Bright Minds
  • 84. 5 Importance of fats and oils - energy - nutrients - thermal insulation - protection to internal organ [Text book: Figure 2.34 pg. 86] Saturated and unsaturated fats - Fat or oil molecules is affected by parent fatty acids. - Fatty acids can be differentiated in two ways; i. the length of the carbon chains (12 to 18 carbon atoms) ii. saturated or unsaturated Saturated fatty acid - All carbon atoms joined together by carbon-carbon single covalent bond. - example: Lauric acid (12 carbon atoms) Palmitic acid (16 carbon atoms) Stearic acid (18 carbon atoms) Bright Minds 016-6412016 Thuran Bright Minds
  • 85. 6 Unsaturated fatty acid - The carbon chain has one or more carbon-carbon double covalent bond. Example: i. Oleic acid: monounsaturated fatty acid (one carbon-carbon double bond)- [no of C = 18, DB = 9&10] ii. Linoleic acid: polyunsaturated fatty acid (two carbon-carbon double bond) [no. of C = 18, DB = 9&10, 12&13] iii. Linolenic acid: polyunsaturated fatty acid (three carbon-carbon dauble bond) [no. of C = 18, DB = 9&10, 12&13, 15&16] Bright Minds 016-6412016 Thuran Bright Minds
  • 86. 7 Saturated Fats - Fats contain esters of glycerol and saturated fatty acids. - Example: i. Tristearin ( glycerol + stearic acid) ii. Tripalmitin (glycerol + palmitic acid) Tristearin H O │ ║ H ― C ― O ― C ― (CH2)16 — CH3 │ │ O │ ║ H ― C ― O ― C ― (CH2)16 — CH3 │ │ O │ ║ H ― C ― O ― C ― (CH2)16 — CH3 │ H Bright Minds 016-6412016 Thuran Bright Minds
  • 87. 8 Tripalmitin - Animal fats have large proportions of saturated fats. - They have high melting point and solids at room temperature. H O │ ║ H ― C ― O ― C ― (CH2)14 — CH3 │ │ O │ ║ H ― C ― O ― C ― (CH2)14 — CH3 │ │ O │ ║ H ― C ― O ― C ― (CH2)14 — CH3 │ H Bright Minds 016-6412016 Thuran Bright Minds
  • 88. 9 Unsaturated Fats - Fats contain esters of glycerol and unsaturated fatty acids. Example: i. Triolein (glycerol + oleic acid) - Plant or vegetable oils contain a large proportions of unsaturated fats. - They have lower melting points and are liquids at room tempoerature. H O │ ║ H ― C ― O ― C ― (CH2)7 — CH ═ CH — (CH2)7 — CH3 │ │ O │ ║ H ― C ― O ― C ― (CH2)7 — CH ═ CH — (CH2)7 — CH3 │ │ O │ ║ H ― C ― O ― C ― (CH2)7 — CH ═ CH — (CH2)7 — CH3 │ H Bright Minds 016-6412016 Thuran Bright Minds
  • 89. 10 Converted unsaturated fats to saturated fats - Unsaturated fats can be converted into saturated fats by process called catalytic hydrogenation. The hydrogenation process is carried out by bubbling hydrogen gas through hot, liquid oil in the presence of fine particles of nickel catalyst. Bright Minds 016-6412016 Thuran Bright Minds
  • 90. 11 Effect of fats on health - Saturated fats (animal oil) will raise the level of cholesterol. - Cholesterol causes fatty deposites or the wall of veins or arteries. - Blood circulation is restricted and will raise the blood presure - Arteriosclerosis, can result in heart attack. - Unsaturated fats (plant oil) do not contain cholesterol. Do not cause cardiovascular problems. Uses of palm oil - Has many advantages. - A cheaper, better and healthier oil. Bright Minds 016-6412016 Thuran Bright Minds
  • 91. 1 Natural Rubber Natural rubber is a natural polymer. Natural rubber is obtained from the latex secreted by rubber tree. Latex is a colloid. It consists of rubber particles dispersed in water. Natural rubber is poly(isopropene). Its monomer is 2-metyhlbuta-1,3-diene or isopropene. Each isopropene molecule contains two pairs of double bonds. Bright Minds 016-6412016 Thuran Bright Minds
  • 92. 2 The isopropene molecules undergo addition polymerization to produce a long-chain molecule called poly(isopropene) Each rubber particles is made up of many long-chain rubber molecules, enclosed by a protein-like membrane which is negatively charged. Negatively-charge protein membrane Long chain rubber molecules Rubber particle ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ Latex Bright Minds 016-6412016 Thuran Bright Minds
  • 93. 3 Polymerization of Isopropene H CH3 H H │ │ │ │ C ═ C ― C ═ C │ │ H H + H CH3 H H │ │ │ │ C ═ C ― C ═ C │ │ H H H CH3 H H │ │ │ │ C ═ C ― C ═ C │ │ H H + H CH3 H H │ │ │ │ ― C − C ═ C − C ― │ │ H H H CH3 H H │ │ │ │ ― C − C ═ C − C ― │ │ H H Isoprene H CH3 H H │ │ │ │ ― C − C ═ C − C ― │ │ H H Repeated unit in polymer polymerization Isoprene Isoprene Bright Minds 016-6412016 Thuran Bright Minds
  • 94. 4 Coagulation process of latex Rubber particle has negatively-charged protein membrane. The repulsion between the negatively-charged particles prevents the rubber particles from coming close to each other. Latex could not coagulate. Rubber particle ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ Bright Minds 016-6412016 Thuran Bright Minds
  • 95. 5 Q: So what causes the latex to coagulate? When an acid is added, the hydrogen ions, H+ neutralize the negative charges on the protein membrane. Q: Can you named the acid that usually used to coagulated the latex in rubber industry? A: Ethanoic acid also known as acetic acid. [notes: all acid solutions can make latex coagulate] ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ + + + ++ + + + + + + + + + + + + + + + + Bright Minds 016-6412016 Thuran Bright Minds
  • 96. 6 Q: What do you think will happen next? The rubber particles now come close together. This enable them to collide with one another resulting in the breakage of the protein membrane. The rubber molecules/polymer combine with one another and entangle. Thus, causing the latex to coagulate. EASY lah Bright Minds 016-6412016 Thuran Bright Minds
  • 97. 7 Q: The coagulation of latex will also occur if latex is exposed to air. Why? A: Bacteria from air can enter latex. The growth and spread of bacteria produce lactic acid that causes the process above. Q: Named the substance can be used to preserve latex in liquid state? Explain. A: Ammonia, NH3. NH3 solutions contains hydroxide ions, OH- that neutralised the acid/hydrogen ions, H+ produced by the bacteria. The rubber particles remain negatively charged and the coagulation is prevented. [notes: all alkaly solutions also can be used] Properties of natural rubber - Soft - Elasticity decreases over time. - Easily oxidized by air. - Sensitive to heat. When heated, it becomes sticky. When cooled, it becomes hard and brittle. Bright Minds 016-6412016 Thuran Bright Minds
  • 98. 8 Vulcanization of rubber Properties of rubber can be improved through vulcanization. Vulcanization is a process whereby rubber is reacted with sulphur to improved its properties. Q: How the vulcanization process is carry out in industry? A: 1st method: Latex is heated with sulphur, or 2nd method: Rubber products are exposed to disulphur dichloride, S2Cl2. Bright Minds 016-6412016 Thuran Bright Minds
  • 99. 9 Q: Compare and contrast the properties of vulcanised and unvulcanised rubber. Similarities Vulcanised and unvulcanised rubber is elastic, and heat and electrical insulator Differences [notes: draw a table] Properties Vulcanised rubber Unvulcanised rubber Elasticity More elastic Less elastic Hardness Harder Softer Tensile strength Stronger Weaker Resistance to heat Can withstand higher temperature Cannot withstand temperature Resistance to oxidation Less easily oxidized Easily oxidized Effect of organic solvent Does not become soft and sticky easily Become soft and sticky easily Bright Minds 016-6412016 Thuran Bright Minds
  • 100. 10 Q: Why? S S C C S S C C S S C C S S C C S S C C S S C C Rubber molecules Cross-linkage of sulphur atoms vulcanisation S S C C S S C C S S C C S S C C S S C C S S C C C═C C═C C═C C═C C═C C═CC═C C═C C═C C═C Natural rubber Vulcanised rubber Bright Minds 016-6412016 Thuran Bright Minds
  • 101. 11 A: Improved properties of vulcanised rubber is due to the presence of cross-linkage of sulphur atoms between the rubber molecules. Q: How the cross-linkage of sulphur atom improve elasticity and strength of the vulcanized rubber: A: When vulcanised rubber is streched and released, the cross linkage pull the chains back to their original arrangement. Q: Why vulcanized rubber more resistant to heat and organic solvent? A: The presence of sulphur cross-linkage increases the size of rubber molecules. Q: Why vulcanized rubber more resistant to oxidation? A: Vulcanized rubber has much lesser carbon-carbon double bond. Bright Minds 016-6412016 Thuran Bright Minds
  • 102. 12 Uses of natural rubber Bright Minds 016-6412016 Thuran Bright Minds
  • 103. 13 SPM Question (2006) Diagram 2 shows the stretching phases of a vulcanised rubber and an unvulcanized rubber strands. Stretching phases Length of vulcanized rubber Length of unvulcanized rubber Before During After Diagram 2 Plan an experiment to compare one characteristic shown in Diagram 2 for both types of rubber. Your planning should include the following aspects: (a) Aim of the experiment (b) All the variables (c) Statement of the hypothesis (d) List of substances and apparatus (e) Procedure of the experiment 50 mm45 mm 60 mm59 mm 45 mm45 mm Bright Minds 016-6412016 Thuran Bright Minds
  • 104. 14 (f ) Tabulation of data [17 marks] Vulcanized rubber 45 59 14 45 unvulcanized rubber 45 60 15 50 Bright Minds 016-6412016 Thuran Bright Minds

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