Carbon chemistry


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Carbon chemistry

  1. 1. Carbon chemistry 1. draw, describe the properties of and make models of the structure of the three allotropes of carbon (diamond, graphite and C60) 2. define the term allotrope 3. make coke from the destructive distillation of coal 4. describe, draw and label a typical carbon cycle diagram. 5. write a report to identify the positive and negative effects of the greenhouse effect 6. prepare carbon dioxide in the laboratory using various methods and write appropriate equations 7. make hokey pokey by the decomposition of sodium hydrogen carbonate 8. describe the properties of carbon dioxide Organic chemistry 9. name and draw alkanes 10. explain the trends in the melting point and boiling point of alkanes as the number of carbon atoms increase. 11. describe how alkanes are separated by fractional distillation. 12. write word and balanced symbol equations for the complete and incomplete combustion of carbon compounds CARBON CHEMISTRY Monday, 1 November 2010
  2. 2. Organic chemistry - cont’d 13. draw and name propene and ethene. 14. write equations for the polymerisation of propene and ethene. 15. name and draw methanol, ethanol and propanol. 16. describe and write equations for the production of ethanol from the fermentation of sugar. 17. describe how ethanoic acid is produced and write its formula. Monday, 1 November 2010
  3. 3. Describe properties and reactions of carbon and its compounds. Monday, 1 November 2010
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  5. 5. GLOSSARY Monday, 1 November 2010
  6. 6. Term Definition Word list Monday, 1 November 2010
  7. 7. NOTES Monday, 1 November 2010
  8. 8. PROPERTIES of Carbon p191 to 194 Monday, 1 November 2010
  9. 9. INTRODUCTION Monday, 1 November 2010
  10. 10. Uses of Carbon BRAIN STORM Why? Monday, 1 November 2010
  12. 12. ORGANISED STRUCTURES Monday, 1 November 2010
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  14. 14. BRAIN STORM CCl Cl Cl Cl CH C H H C H THREE pairs are shared Monday, 1 November 2010
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  16. 16. DIAMOND & GRAPHITE Allotropes are different physical forms of the same element. Allotropes have the same chemical properties but different physical properties. Structures are based on covalent bonding • A colourless, solid which is very hard. • High density, high melting point. • Very poor electrical conductor but a very good heat conductor In diamond Each carbon atom bonds covalently to four other carbon atoms to form a 3D network: Allotropes of Carbon • A grey, shiny solid which is slippery to the touch and soft. • Low density, high melting point. • Excellent electrical conductor • The stable form of Carbon In graphite Covalent bonding to three other carbon atoms to form a sheet or layer. Same chemical properties: eg. complete & incomplete combustion Monday, 1 November 2010
  17. 17. Graphite • Weak bonds between layers allow layers to slide past each other => good lubricant • Electrons between layers are not held strongly by the carbon atoms in the layers => good electrical conductivity Diamond • Each of the four electrons is involved in a strong covalent bond and is not free to move => poor electrical conductivity. • With a 3D network of strong covalent bonds the diamond structure is very hard. LINKING STRUCTURE TO PROPERTIES Monday, 1 November 2010
  18. 18. C60 Covalent bonding to three other carbon atoms: Hexagonal faces Pentagonal faces Buckminsterfullerine is hollow and shaped like a soccer ball Monday, 1 November 2010
  19. 19. Diamond is the ultimate gemstone, having few weaknesses and many strengths. It is well known that Diamond is the hardest substance found in nature, but few people realize that Diamond is four times harder than the next hardest natural mineral, corundum (sapphire and ruby). But even as hard as it is, it is not impervious. Diamond has four directions of cleavage, meaning that if it receives a sharp blow in one of these directions it will cleave, or split. A skilled diamond setter and/or jeweler will prevent any of these directions from being in a position to be struck while mounted in a jewelry piece. As a gemstone, Diamond's single flaw (perfect cleavage) is far outdistanced by the sum of its positive qualities. It has a broad color range, high refraction, high dispersion or fire, very low reactivity to chemicals, rarity, and of course, extreme hardness and durability. Diamond is the April Birthstone. In terms of it's physical properties, diamond is the ultimate mineral in several ways: • Hardness: Diamond is a perfect "10", defining the top of the hardness scale, and by absolute measures four times harder than sapphire (which is #9 on that scale). • Clarity: Diamond is transparent over a larger range of wavelengths (from the ultraviolet into the far infrared) than is any other solid or liquid substance - nothing else even comes close. • Thermal Conductivity: Diamond conducts heat better than anything - five times better than the second best element, Silver! • Melting Point: Diamond has the highest melting point (3820 degrees Kelvin) • Lattice Density: The atoms of Diamond are packed closer together than are the atoms of any other substance • Tensile Strength: Diamond has the highest tensile strength of any material, at 2.8 gigapascals. However, that does not quite translate into the strongest rope or cable, as diamond has cleavage planes which support crack propagation. The strongest ropes can likely be made from another material, carbon nanotubes, as they should not suffer from the effects of cracks and break. Still, if a long, thin, perfect crystal of diamond could be manufactured, it would offer the highest possible pulling strength (in a straight line - don't try to tie it in a knot!) • Compressive Strength: Diamond was once thought to be the material most resistant to compression (the least compressible). It is the material that scientists use to create the greatest pressures when testing matter. However, the rare metal Osmium has recently been shown to be even less compressible (although it is not as hard as diamond). Diamond has a bulk modulus (reciprocal of compressibility) of 443 GigaPascals (GPa). The bulk modulus of the metal osmium has recently been found to be 476 GPa, about 7% greater than diamond. Diamond is a polymorph of the element carbon. Graphite is another polymorph. The two share the same chemistry, carbon, but have very different structures and properties. Diamond is hard, Graphite is soft (the "lead" of a pencil). Diamond is an excellent electrical insulator, Graphite is a good conductor of electricity. Diamond is the ultimate abrasive, Graphite is a very good lubricant. Diamond is transparent, Graphite is opaque. Diamond crystallizes in the Isometric system and graphite crystallizes in the hexagonal system. Somewhat of a surprise is that at surface temperatures and pressures, Graphite is the stable form of carbon. In fact, all diamonds at or near the surface of the Earth are currently undergoing a transformation into Graphite. This reaction, fortunately, is extremely slow. Monday, 1 November 2010
  20. 20. CARBON: PROPERTIES & BONDING Monday, 1 November 2010
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  22. 22. CARBON CYCLE p191 to 194 Monday, 1 November 2010
  23. 23. GLOBAL WARMING Monday, 1 November 2010
  24. 24. CARBON CYCLE 2 basic processes involved in carbon cycling: • Photosynthesis: Carbon dioxide + water + sunlight ----> Glucose + oxygen • Respiration: Glucose + oxygen ----> Carbon dioxide + water Major carbon sinks: • Plants absorb carbon dioxide through photosynthesis • Water (in the sea) - absorb carbon dioxide because carbon dioxide is slightly soluble in water. Molecules Long carbon chains are the basis of all living things - there are 4 possible types of bond that a carbon atom can form in a chain. USES OF CARBON 1. READ the handout provided and make a short summary in your notes of the content provided. 2. Answer the questions (on the whiteboard) as FULL SENTENCES in your exercise books. p196, 197 ESA Monday, 1 November 2010
  25. 25. QUESTIONS 1. For the element Carbon, name two sources of the element of commercial value and give some indication of the abundance of the source on planet Earth, eg. large, moderate or rare. 2. Supply the missing words to describe the following process (words may be used more than once in the answer - the number of letters in the words is shown by the dashes): Coal heated in the absence of air produces _ _ _ _, gases and oils. _ _ _ _ is a purer form of the element _ _ _ _ _ _ than coal. 3. Complete the following equations. If the equation is in words, then use words to complete the equation. It the equation is in symbols, then use symbols to complete the equation. The number of letters in the words or symbols is shown by the dashes. (a) Carbon dioxide + oxygen ---> ________________________ (two words) (b) Carbon dioxide + water ----> __________ + ___________ (photosynthesis) (c) __ZnO(s) + C(s) ---> __Zn + _____(g) 4. Explain the meaning of the underlined words in the following passage. Carbon can be used as a fuel. It will combine with oxygen exothermically to produce carbon dioxide. Coal is a mineral (naturally occurring substance that is mined) that is mainly carbon. Other minerals of carbon that are fuels are petroleum and natural gas. Monday, 1 November 2010
  26. 26. THE CARBON CYCLE - an experimental view Monday, 1 November 2010
  27. 27. Label the diagram using the word list (below) 1. Plant respiration 2. Animal respiration 3. Photosynthesis 4. Dead organisms and waste products 5. Root respiration 6. Fossils and Fossil fuels 7. Ocean uptake 8. CO2 Cycle CARBON CYCLE Monday, 1 November 2010
  28. 28. ANSWERS Monday, 1 November 2010
  29. 29. CARBON DIOXIDE p191 to 194 Monday, 1 November 2010
  30. 30. PROPERTIES OF CARBON DIOXIDE Physical • Colourless, sweet smelling gas that is non-toxic in low concentrations • More dense than air, will not undergo thermal decomposition and inability to support combustion ---> use in fire extinguishers • Poor solubility in water (that increases with pressure) • Sublimes (does not enter the liquid state) --> dry ice for stage effects Chemical • turns limewater milky but if it continues to be added to limewater then limewater will revert to being colourless • dissolves in water to form an acidic solution (carbonic acid) • Carbon dioxide can be released from a carbonic acid solution that has been under pressure (for example, in a fizzy drink) Preparation Carbonate/acid reactions produce carbon dioxide in the lab. Collection by downward displacement of water. Calcium carbonate Hydrochloric acid Delivery tube Stopper Test tube Water Monday, 1 November 2010
  31. 31. COMPLETE AND INCOMPLETE COMBUSTION Monday, 1 November 2010
  32. 32. REACTIONS INVOLVING CARBON DIOXIDE The limewater test The precipitate that gives limewater the milky appearance Carbonic acid formation CO2(g) + H2O(l) ---> H2CO3(aq) Acid rain dissolving limestone H2CO3(aq) + CaCO3(s) ---> Ca(HCO3)2(aq) a reaction that occurs more readily at higher pressures it is reversed when the pressure is released: H2CO3(aq) ---> CO2(g) + H2O(l) Monday, 1 November 2010
  33. 33. ALKANES Monday, 1 November 2010
  34. 34. INTRODUCTION Definition • Alkanes are part of a family of compounds called hydrocarbons because the only elements in these compounds are Hydrogen and Carbon. • They have the general formula: CnH2n + 2 (which means that for every atom of carbon in an alkane molecule there are twice as many Hydrogen atoms plus two). • Hydrocarbons are useful to us because they can combine with oxygen during combustion to produce energy and because they occur naturally in fossil fuels. • Complete combustion of a hydrocarbon will produce carbon dioxide and water. • Straight chain alkanes contain carbon atoms that are joined to no more than two other carbon atoms Monday, 1 November 2010
  35. 35. Melting and boiling point - butane is solid below its melting point of -139o C and a liquid below its boiling point of 0o C. Therefore at room temperature, butane is a gas. Structural formula - a formula that in addition shows how the atoms are connected. Molecular formula - a formula that gives the number and type of atom in a molecule. “ 4 atoms of carbon are bonded covalently to 8 atoms of hydrogen to make up a molecule of butane” C4H8 means: primary carbon atom secondary carbon atom C - C - C - CC - C - C - C H H H H HH H H H H OR BUTANE Monday, 1 November 2010
  36. 36. trivial naming systematic naming NAMING, DRAWING AND TRENDS IN PHYSICAL PROPERTIES Monday, 1 November 2010
  37. 37. EXERCISES Use your table to graph the melting and boiling points of alkanes against the number of carbon atoms in the molecule. number of carbon atoms Temperature (o C) Monday, 1 November 2010
  38. 38. Questions 1. Draw lines on your graph to show how you would use your graph to find the boiling point (in o C) of the alkane which has 5 carbon atoms? 2. Explain the trend in melting and boiling points that is shown by your graph. 3. Explain the term “straight chain” when used to describe alkanes. 4. Explain what is meant by the terms (i) boiling point (ii) melting point Monday, 1 November 2010
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  44. 44. COMPLETE & INCOMPLETE COMBUSTION Complete combustion occurs when an alkane combines with oxygen in plentiful supply, to produce carbon dioxide, water and heat according to the following general equation: Incomplete combustion occurs when an alkane combines with oxygen in limited supply, to produce carbon monoxide, water and heat according to the following general equation: alkane + oxygen ---> carbon dioxide + waterGeneral equation: Example: alkane + oxygen ---> carbon monoxide + waterGeneral equation: Example: Butane + oxygen ---> carbon dioxide + water butane + oxygen ---> carbon monoxide + water ______ + ________ ---> _____ + _______ ______ + ________ ---> _____ + _______ Monday, 1 November 2010
  45. 45. EXERCISES Monday, 1 November 2010
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  47. 47. EXERCISES ON ALKANES Monday, 1 November 2010
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  49. 49. FRACTIONAL DISTILLATION Monday, 1 November 2010
  50. 50. EXERCISES 1. Read the sheet provided (p210, ESA Study Guide) 2. Take notes in your book (ensuring that you have a written explanation in your notes that allows you to understand the process) 3. You may use the sheet to help you with the “Fractional distillation matchup” exercise that follows Monday, 1 November 2010
  51. 51. FRACTIONALDISTILLATIONMATCHUP Monday, 1 November 2010
  52. 52. fractions decreasing in density and boiling pt fractionating column crude oil C1 to C4 gases (20o C) C5 to C9 naptha (70o C) C5 to C10 gasoline (120o C) C10 to C16 paraffin oil (170o C) C14 to C20 diesel oils (270o C) C20 to C50 lubricating oil C20 to C70 fuel oil (600o C) liquefied petroleum gas chemicals petrol for vehicles jet fuel, paraffin for heating and lighting diesel fuels lubricating oil, waxes & polishes fuels for ships, factories and central heating bitumen for roads and roofing Monday, 1 November 2010
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  54. 54. ALKENES Monday, 1 November 2010
  55. 55. Definition • Alkenes are also hydrocarbons which form a series of compounds. They are different to alkanes in that there carbon atoms that are double bonded to each other. They are similar that they are both insoluble in water. They have the general formula: CnH2n (which means that for every atom of carbon in an alkane molecule there are twice as many Hydrogen atoms). • Alkenes also undergo combustion reactions. Complete and incomplete combustion occur in a similar way to alkanes. • Complete combustion of a hydrocarbon will produce carbon dioxide and water. ALKENES: STRUCTURE & PROPERTIES 1. Use the molymods to make ethene and propene (drawn below). 2. What do you notice about how close the double bonded carbons are to each other? 3. Count the numbers of carbon and hydrogen atoms in each molecule and using the term “n” to indicate the number of atoms in the molecule, write the general equation for alkenes in your book. C C CEthene Propene C C Monday, 1 November 2010
  56. 56. THE DOUBLE BOND AND POLYMERISATION • The double bond in alkenes is physically stronger than single bonds. • It is however a point of reactivity because there is a greater concentration of electrons between the two carbon atoms than if the carbon atoms were single bonded. • The double bond in an ethene can be broken to make electrons available for bonding with other ethene molecules: C C +C C C C C C C C Two single electrons that can be shared as part of a bond C C a monomer a dimer ethene Many of these units bonded together makes a polymer Monday, 1 November 2010
  57. 57. THE DOUBLE BOND AND REACTIVITY • When the double bond in alkenes is broken, the carbon atoms become available for bonding with other atoms such as bromine and chlorine. All bonds are now single bonds and the compound is said to be saturated. C C C C dibromoethaneBr2 Br Br • A hydrocarbon that contains double bonds is unsaturated. Another example C C a monomerbutene CH2CH3 C C CH2CH3 Many of these units bonded together makes a polymer Monday, 1 November 2010
  58. 58. EXERCISES 1. Write 3 equations for the combustion of each of ethene and butene: (i) where carbon dioxide is a product (complete combustion) (ii) where carbon monoxide is a product (incomplete combustion) (iii) where carbon is a product (incomplete combustion) Monday, 1 November 2010
  59. 59. ALCHOLS Monday, 1 November 2010
  60. 60. METHANOL & ETHANOL Distillation • Methanol & ethanol are the first two alcohols in a series of carbon compounds. • Each molecule is that of an alkane with an -OH group in place of one of the hydrogen atoms Solubility Alcohols are soluble. Alkanes and alkenes are not because the -OH group is polar and can attract polar water molecules: C - C O HC O H H H H H H H H H Methanol Ethanol H H O - + + C O H H H H + - Monday, 1 November 2010
  61. 61. SYNTHETIC ALCOHOL PRODUCTION CH4(g) + H2O(g) ---> CO(g) + H2(g) 1. Use the equations (below) to complete a flow diagram of the process. In your flow diagram, USE CHEMICAL NAMES instead of formulae. 2. The equations (above) are unbalanced. BALANCE THEM. CO(g) + 2H2(g) ---> CH3OH(g) Step 1 Step 2 800 - 850o C Nickel catalyst 800 - 850o C High Pressure Monday, 1 November 2010
  62. 62. ALCOHOL PRODUCTION by fermentation 2(C6H10O5)n(aq) + nH2O(l) ---> nC12H22O11(aq) Use the equations (above) to complete a flow diagram of the process. In your flow diagram, USE CHEMICAL NAMES instead of formulae. Step 1 Step 3 Step 2 enzyme amylase C12H22O11(aq) + H2O(l) ---> 2C6H12O6(aq) 2(C6H12O6)(aq) ---> 2C2H5OH(aq) + 2CO2(g) enzyme amylase starch maltose glucose enzyme zymase maltose glucose glucose Monday, 1 November 2010
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  64. 64. EXERCISES1. READ p89 Y11 Pathfinder Science 2. Comparing physical properties (methanol, ethanol, methane and ethane) Monday, 1 November 2010
  65. 65. ETHANOIC ACID Monday, 1 November 2010
  66. 66. ETHANOIC ACID • Also called acetic acid. • Formed by the oxidation of ethanol. • Ethanol in beer and wine will be oxidised to ethanoic acid under certain conditions. UV light causes this oxidation to occur more rapidly which explains the use of coloured bottles and cardboard enclosures (beer). Structures: C - C O HH H H H H Ethanol C - C O HH H H Ethanoic acid O O2 Physical properties: • Sour taste • Colourless solid • soluble Monday, 1 November 2010
  67. 67. PRACTICALS Monday, 1 November 2010
  68. 68. CARBON DIOXIDE p191 to 194 Monday, 1 November 2010
  69. 69. SUBLIMATION for Screen effects Monday, 1 November 2010
  70. 70. 250 mL beaker candles (of different lengths placed into film cannisters) baking soda Vinegar EXTINGUISHING FLAMES Observation Conclusion Monday, 1 November 2010
  71. 71. Calcium carbonate Hydrochloric acid Delivery tube Stopper Test tube Water LAB PREPARATION AND REACTION WITH LIMEWATER Observation Conclusion Relevant chemical equations: Monday, 1 November 2010
  72. 72. Gas jar Deflagrating spoon Burning Charcoal Water with a few drops of UI added INVESTIGATING THE SOLUBILITY AND THE ACIDIC PROPERTIES 1 2 Observation Conclusion Swirly thoroughly Monday, 1 November 2010
  73. 73. Vinegar Baking soda Baking soda & vinegar -> Allow it to stop fizzing -> pour into 2nd gas jar and seal with a lid 1 2 3 INVESTIGATING DENSITY Observation Conclusion limewater test for CO2 glass lid Invert a clean gas jar over the 1st and leave for 2 minutes Monday, 1 November 2010
  74. 74. CARBON DIOXIDE by thermal decomposition Monday, 1 November 2010
  75. 75. 2 Observation Conclusion CARBON DIOXIDE FROM DECOMPOSITION REACTIONS Limewater Pour the gas into limewater and swirl test-tube Bunsen burner (blue flame) (a) Sodium Hydrogen Carbonate (b) Calcium Carbonate 1 Use the decomposition of two different compounds to produce CO2 and test for the gas with limewater: Monday, 1 November 2010
  76. 76. DESTRUCTIVE DISTILLATION OF COAL Monday, 1 November 2010
  77. 77. p7 ABA Monday, 1 November 2010
  78. 78. MAKING ALKANES USING MOLYMODS Monday, 1 November 2010
  80. 80. ALKANE & ALCOHOLS Monday, 1 November 2010
  81. 81. _____________ _____________ _____________ _____________ Solution (Ethanol and water) Word List distillate vapour condenser boils thermometer liquid round bottom flask water cooled We were able to separate the ethanol from the water because the ethanol _____________ at a lower temperature than the ________. The ethanol _________ passes into the ____________ where it is ___________ to become a __________ . DISTILLATION Monday, 1 November 2010
  82. 82. EXAM QUESTIONS 2003, 2004, 2005, 2009 Monday, 1 November 2010
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