Alkane

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Alkane

  1. 1. ALKENE<br />
  2. 2.
  3. 3. C<br />C<br />Atom carbon<br />2, 4<br />Atom carbon<br />2, 4<br />
  4. 4. C<br />C<br />Atom carbon<br />2, 4<br />Atom carbon<br />2, 4<br />
  5. 5. C<br />C<br />Atom carbon<br />2, 6<br />Atom carbon<br />2, 6<br />
  6. 6. H<br />Atom hydrogen<br />1<br />C<br />C<br />Atom carbon<br />2, 6<br />Atom carbon<br />2, 6<br />
  7. 7. H<br />Atom hydrogen<br />2<br />C<br />C<br />Atom carbon<br />2, 7<br />Atom carbon<br />2, 6<br />
  8. 8. H<br />H<br />Atom hydrogen<br />2<br />C<br />C<br />Atom carbon<br />2, 7<br />Atom carbon<br />2, 6<br />
  9. 9. H<br />H<br />Atom hydrogen<br />2<br />C<br />C<br />Atom carbon<br />2, 8<br />Atom carbon<br />2, 6<br />
  10. 10. H<br />H<br />H<br />Atom hydrogen<br />2<br />C<br />C<br />Atom carbon<br />2, 8<br />Atom carbon<br />2, 6<br />
  11. 11. H<br />H<br />H<br />Atom hydrogen<br />2<br />C<br />C<br />Atom carbon<br />2, 8<br />Atom carbon<br />2, 7<br />
  12. 12. H<br />H<br />H<br />H<br />Atom hydrogen<br />2<br />C<br />C<br />Atom carbon<br />2, 8<br />Atom carbon<br />2, 7<br />
  13. 13. H<br />H<br />H<br />H<br />Atom hydrogen<br />2<br />C<br />C<br />Atom carbon<br />2, 8<br />Atom carbon<br />2, 8<br />
  14. 14. It is classified as unsaturated hydrocarbons.<br />(An unsaturated hydrocarbon contains at least one double covalent bonds between carbon atoms).<br />Alkenes are hydrocarbons with the general formula :<br />CnH2n where n = 2, 3, ……, ∞<br />Every alkene has a carbon-carbon double covalent bond, C = C in its molecule.<br />
  15. 15. H<br />H<br />H<br />C<br />C<br />H<br />Example : Formation of an ethene molecule<br />(a) Ethene, C2H4<br />H<br />H<br />C<br />C<br />H<br />H<br /> Structural formula for ethane, C2H4<br /><ul><li>The first member of alkenes has two carbon </li></ul>atoms in a molecule because <br /> ……………………. bond is formed between two carbon atoms.<br />double <br />
  16. 16. Naming of Alkenes<br />The name of straight chain alkenes are also made up of two component parts :<br />(i) Stem/root : indicates the number of carbon atoms in the longest continuous carbon chain.<br />The names of stems for the first nine straight alkanes are :<br />eth, prop, but, pent, hex, hept, oct, non anddec<br />(ii) Suffix/ ending : indicates the group of the compound.<br />For alkene, the suffix is ‘ene’ because it belongs to the alkene group.<br />
  17. 17. 4.Naming of Alkenes<br />a) Naming the straight chainalkene :<br />(i) Determine the longest carbon chain containing double bond.<br />give the stem name according to the number of carbon atoms ; <br />eth, prop, but, pent, hex, hept, oct, non anddec<br />(ii) Add the suffix “ene” at the end of the name.<br />(iii) Number the carbon atoms from the end nearer to the double bond and give the double bond the smaller number.<br />
  18. 18. <ul><li>.</li></ul>Activity 6 :-<br />Complete the table below :<br />5.Physical properties of Alkenes are similar to alkanes<br />
  19. 19. Activity 7 :-<br />Complete the following table :<br />
  20. 20. <ul><li>Physical state at room temperature (25 OC) :</li></ul>Ethene, propene and but-1-ene are …………………..<br />Pent-1-ene to non-1-ene are ………………….. and dec-1-ene is …………………..<br /><ul><li>Alkenes have ………………….. melting and boiling points because the ………………….. van deer Waals forces (intermolecular forces) between small molecules need ……………… amount of heat energy to overcome the forces.
  21. 21. As the number of carbon atoms per molecule increases, the molecular size of alkene …………………., the ………………….. the intermolecular forces, more ………………….. energy is needed to ………………….. this forces, the melting and boiling points …………………..</li></ul>gas<br />liquid<br />solid<br />Low <br />weak<br />Low <br />increases<br />Stronger <br />overcome<br />Heat <br />increases<br />
  22. 22. 6.Chemical properties of Alkenes<br />more<br />(a) Alkenes are chemically ………………….. reactive than alkanes because of the existence of double covalent bond between two carbon atoms.<br />Almost all of the chemical reactions of alkene occur at the double bond.<br />(b) The chemical reactions of alkenes are :<br />I : Combustion Reaction<br /><ul><li>Alkene burns completely in the excess oxygen to produce ……………………. and ……………</li></ul>Alkene + O2 -> CO2 + H2O <br />Carbon dioxide<br />water<br />
  23. 23. Activity 8 :-<br />1.Balance the following equations :<br />C2H4 + O2 -> CO2 + H2O<br />C3H6 + O2 -> CO2 + H2O<br />C4H8 + O2 -> CO2 + H2O<br />2.Write the balanced equation for combustion reaction of :<br />Pentene:………………………………………………………<br />Hexene:………………………………………………………<br />Octene:…………………………………………………………<br />
  24. 24. <ul><li>However, alkene burns incompletely (in limited supply of oxygen) to form carbon dioxide, carbon monoxide, carbon (in the form of soot) and water.</li></ul>Example : <br />2C2H4+ 3O2 2C + 2CO + 2H2O<br />or<br />C2H4+ 2O22CO + 2H2O <br />
  25. 25.
  26. 26. Addition reaction<br />II : Addition Reaction<br /><ul><li>As alkenes are unsaturated hydrocarbon, they undergo addition reaction.</li></ul>An addition reaction is a reaction in which other atoms are added to each carbon atom of the ……………….. bond, [C = C ] to form ……………….. covalent bond product [ C - C ].<br />double <br />Single <br /> C = C + XY C C<br />XY<br /> (unsaturated) (saturated )<br />
  27. 27.
  28. 28. Simple molecules like hydrogen, H2 ; hydrogen chloride, HCl ; water, H2O or halogens, [F2, Cl2, Br2, I2] can be added to the double bond. <br /> (i) Addition of Hydrogen (Hydrogenation)<br /><ul><li>Alkenes react with hydrogen at 180 Cin the presence of nickel/platinum as a catalyst to produce alkanes.
  29. 29. Hydrogenation is used to prepare an alkane (saturated compound) from an alkene (unsaturated compound) in industry.</li></ul>Example : <br />Ni / Pt<br />180 C<br />Ethene Ethane<br />+ H2<br />
  30. 30.
  31. 31. (ii) Addition of Halogen (Halogenation)<br /><ul><li>Alkenes react with halogens such as chlorine,Cl2 and bromine, Br2 at room conditions.</li></ul>(nocatalystorultraviolet light needed)<br />Example : <br />+ Br2<br />Ethene (bromine water) <br /><ul><li>When ethene gas is passed through bromine water, brown colour of bromine water is decolourised // colourless solution formed.
  32. 32. This reaction is used to distiguish a saturated hydrocarbon and unsaturated hydrocarbon. </li></ul>1,2-dibromoethane<br />
  33. 33. C2H4 gas<br />Bromine water<br />(nocatalystorultraviolet light needed)<br />
  34. 34. before<br />after<br />alkene<br />Alkane<br />
  35. 35. Which is alkene?<br />
  36. 36.
  37. 37. iii)Addition of Hydrogen Halide [ HX HCl, HBr, HI ]<br /><ul><li>Alkenes react with hydrogen halide such as hydrogen chloride, HCl or hydrogen bromide, HBr at room temperature to form haloalkane.</li></ul>Example : <br /> C2H4 + HCl -> C2H5Cl <br />Ethene Hydrogen chloride Chloroethane<br /> C3H6 + HBr -> <br />PropeneHydrogen bromide ………………….<br />
  38. 38. Activity 9 :-<br />Complete the equation and draw the structural formulae for all the reactants and products in the equation below :<br />1 (a) C3H6 + H2 -> C3H8<br /> (b) C4H8 + H2 -> ……….<br /> (c) ………. + H2 -> C6H14<br />2 (a) C3H6 + Br2 -> C3H6Br2<br />(b) C4H8 + Cl2 -> ……….<br /> (c) ………. + I2 -> C6H12I2<br />
  39. 39. iv)Addition of Oxidizing agent : (Oxidation reaction)<br /><ul><li>Acidified Potassium manganate(VII), KMnO4 solution
  40. 40. AcidifiedPotassium dichroromate(VI), K2Cr2O7 solution
  41. 41. In this reaction, two hydroxyl, -OH groups are added to the carbon-carbon …………………… in an alkene molecule.
  42. 42. An alkene…………………… the ………………… colour of acidified potassium manganate(VII)solution //the orangesolution of acidified Potassium dicrhoromate(VI), K2Cr2O7turns to ……………………</li></ul>This reaction is used to distiguish a …………………… hydrocarbon and …………………… hydrocarbon<br />double bond<br />Decolorized <br />purple<br />green<br />saturated<br />unsaturated<br />
  43. 43. Example :<br />KMnO4(aq)<br />[Purple]<br />Alkene<br />Colourless<br />KMnO4<br />C2H6 gas<br />C2H4 + H2O + [O] -> C2H4(OH)2<br />Ethene Ethan-1,2-diol<br />colourless<br />
  44. 44. Activity10 :-<br />Propan-1,2-diol<br />Ethan-1,2-diol<br />☺Complete the following equation :<br />(a) C3H6 + H2O + [O] -> C3H6(OH)2<br />H H<br />(b) H C = C H + H2O + [O] -><br />H<br />H<br />H<br />H<br />C<br />C<br />OH<br />OH<br />
  45. 45. KMnO4<br />
  46. 46. v)Addition of Water (Hydration)<br /><ul><li>Alkenes react with water (in the form ofsteam) at high temperature and pressure in the presence of phosphoric acid as a catalyst to produce alchohols.</li></ul>H3PO4<br />300 C / 60 atm<br />Alkene + H2O Alcohol<br />Example :<br />C2H4 + H2O C2H5OH <br />Etheneethanol<br />H3PO4<br />300 C / 60 atm<br />
  47. 47. alkene<br />alcohol<br />
  48. 48.
  49. 49. Activity 11 :-<br />☺Complete the following equation <br />H3PO4<br />300 C / 60 atm<br />C3H6 + H2O <br />H3PO4<br />300 C / 60 atm<br />+H20<br />
  50. 50. <ul><li>Addition of steam to alkene is one way to manufacture alcohol in industry </li></ul>H3PO4<br />300 C / 60 atm<br />CnH2n + H2O(g) CnH2n+1OH <br />Alcohol <br />Alkene<br />Example :<br />C4H8 + H2O <br />H3PO4<br />300 C / 60 atm<br />Butene<br />
  51. 51. vi)Addition Polymerisation reaction<br /><ul><li>In this reaction, small alkene molecules undergo addition reaction at a high pressure of 1000 atm and temperature of 200 C. Thousands of alkene molecule join together to form long chain giant molecules called …………………………
  52. 52. The smallrepeating units of molecules that join together to form polymer are called …………………………</li></ul>polymer<br />monomer<br />n<br />Ethene<br />Polythene<br />
  53. 53.
  54. 54.
  55. 55.
  56. 56.
  57. 57. Activity 12 :-<br />☺Polymerisation of propene, C3H6<br />n<br />propene<br />
  58. 58. ☺Polymerisation of butane, C4H8<br />n<br />
  59. 59. COMPARING PROPERTIES OF ALKANE WITH ALKENE (Using hexane and hexene in the laboratory) <br />

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