Chemical Reactions

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Chemical Reactions

  1. 1. CHEMICAL REACTIONS 1. Describe chemical change in terms of formulae, equations and valency. 2. Recognise oxidation and reduction in terms of electron transfer. 3. Recognise oxidation and reduction in terms of transfer of oxygen and hydrogen. 4. Explain the mechanism of dissolving and explain the formation of a precipitate. 5. Predict the identity of a precipitate in a precipitation reaction. 6. Describe thermal decomposition of metal hydroxides, carbonates and hydrogen carbonates. 7. Show an understanding of atomic an molecular masses. 8. Calculate percentage composition of compounds. 9. Calculate empirical formulae from data relating to percentage composition. 10.Calculate mass ratios of chemicals involved in chemical reactions. Thursday, 16 September 2010
  2. 2. Thursday, 16 September 2010
  3. 3. Thursday, 16 September 2010
  4. 4. Thursday, 16 September 2010
  5. 5. LANGUAGE Thursday, 16 September 2010
  6. 6. Term Ans Definition GLOSSARY 1 Match the term with its definition > ans’s only in BOB A. Valency B. Ion C. Reactants D. Products E. Oxidation F. Reduction G. Half - equation Thursday, 16 September 2010
  7. 7. Term Definition GLOSSARY 1- HANDOUT A. Ion B. Precipitate C. Species D. Redox 4. a term that describes any oxidation-reduction reaction Thursday, 16 September 2010
  8. 8. Term Ans Definition GLOSSARY 2 Match the term with its definition > ans’s only in BOB Thursday, 16 September 2010
  9. 9. Term Definition GLOSSARY 2- HANDOUT Thursday, 16 September 2010
  10. 10. FORMULAE AND EQUATIONS Thursday, 16 September 2010
  11. 11. FORMULAE Thursday, 16 September 2010
  12. 12. VALENCY Copy Valency is a term that allows us to predict how an atom will bond with other atoms. It is given as a number. Two ways of thinking about valency: 1. For ionic compounds it is the number of electrons that an atom will gain or lose in order for it to gain an octet/duet of electrons. 2. For covalent compounds it is the number of bonds that it will form that will allow it to gain an octet/duet. Examples Oxygen, O has a valency of 2. (it will gain two electrons to form an octet when it forms an ionic compound or share two electrons to form an octet when it forms a covalent compound) • MgO (the Oxygen atom has a 2- charge in this compound) • CO2 (Each O atom has formed 2 bonds with carbon in this compound) Repeat the above illustration for Phosphorus. Use Phosphorus trichloride and Sodium phosphide as the compounds ESA: p61 - 63 Ex 8A Thursday, 16 September 2010
  13. 13. WRITING FORMULAE Copy Examples Use your table of ions to write formluae for the following ionic compounds: Sodium Fluoride _____________ Magnesium Oxide __________ Sodium Oxide _______________ Zinc Chloride _____________ Lead Nitrate ______________ Potassium Sulphate ____________ Calcium Hydrogen Carbonate __________ Aluminium Oxide _______ THE PROCESS FOR WRITING FORMULAE Thursday, 16 September 2010
  14. 14. WRITING FORMULAE Copy Examples Use your table of ions to write formluae for the following ionic compounds: Sodium Fluoride _____________ Magnesium Oxide __________ Sodium Oxide _______________ Zinc Chloride _____________ Lead Nitrate ______________ Potassium Sulphate ____________ Calcium Hydrogen Carbonate __________ Aluminium Oxide _______ Method 1: Working with ratios THE PROCESS FOR WRITING FORMULAE Example Write the formula for Calcium bicarbonate Thursday, 16 September 2010
  15. 15. WRITING FORMULAE Copy Examples Use your table of ions to write formluae for the following ionic compounds: Sodium Fluoride _____________ Magnesium Oxide __________ Sodium Oxide _______________ Zinc Chloride _____________ Lead Nitrate ______________ Potassium Sulphate ____________ Calcium Hydrogen Carbonate __________ Aluminium Oxide _______ Method 1: Working with ratios THE PROCESS FOR WRITING FORMULAE Example 1. Work out the ratio of ions Write the formula that will cause a balance for Calcium of positive & negative bicarbonate charges Thursday, 16 September 2010
  16. 16. WRITING FORMULAE Copy Examples Use your table of ions to write formluae for the following ionic compounds: Sodium Fluoride _____________ Magnesium Oxide __________ Sodium Oxide _______________ Zinc Chloride _____________ Lead Nitrate ______________ Potassium Sulphate ____________ Calcium Hydrogen Carbonate __________ Aluminium Oxide _______ Method 1: Working with ratios THE PROCESS FOR WRITING FORMULAE Example 1. Work out the ratio of ions Write the formula for Calcium that will cause a balance 1 Ca2+ HCO3 - of positive & negative bicarbonate 1 : 2 charges Thursday, 16 September 2010
  17. 17. WRITING FORMULAE Copy Examples Use your table of ions to write formluae for the following ionic compounds: Sodium Fluoride _____________ Magnesium Oxide __________ Sodium Oxide _______________ Zinc Chloride _____________ Lead Nitrate ______________ Potassium Sulphate ____________ Calcium Hydrogen Carbonate __________ Aluminium Oxide _______ Method 1: Working with ratios THE PROCESS FOR WRITING FORMULAE Example 1. Work out the ratio of ions Write the formula for Calcium that will cause a balance 1 Ca2+ HCO3 - of positive & negative bicarbonate 1 : 2 charges 2. Writing it out without the charges Thursday, 16 September 2010
  18. 18. WRITING FORMULAE Copy Examples Use your table of ions to write formluae for the following ionic compounds: Sodium Fluoride _____________ Magnesium Oxide __________ Sodium Oxide _______________ Zinc Chloride _____________ Lead Nitrate ______________ Potassium Sulphate ____________ Calcium Hydrogen Carbonate __________ Aluminium Oxide _______ Method 1: Working with ratios THE PROCESS FOR WRITING FORMULAE Example 1. Work out the ratio of ions Write the formula for Calcium that will cause a balance 1 Ca2+ HCO3 - of positive & negative bicarbonate 1 : 2 charges 2. Writing it out without the charges 2 Ca HCO3 Thursday, 16 September 2010
  19. 19. WRITING FORMULAE Copy Examples Use your table of ions to write formluae for the following ionic compounds: Sodium Fluoride _____________ Magnesium Oxide __________ Sodium Oxide _______________ Zinc Chloride _____________ Lead Nitrate ______________ Potassium Sulphate ____________ Calcium Hydrogen Carbonate __________ Aluminium Oxide _______ Method 1: Working with ratios THE PROCESS FOR WRITING FORMULAE Example 1. Work out the ratio of ions Write the formula for Calcium that will cause a balance 1 Ca2+ HCO3 - of positive & negative bicarbonate 1 : 2 charges 2. Writing it out without the charges 2 Ca HCO3 3. Put the subscripts in place to reflect the ratio Thursday, 16 September 2010
  20. 20. WRITING FORMULAE Copy Examples Use your table of ions to write formluae for the following ionic compounds: Sodium Fluoride _____________ Magnesium Oxide __________ Sodium Oxide _______________ Zinc Chloride _____________ Lead Nitrate ______________ Potassium Sulphate ____________ Calcium Hydrogen Carbonate __________ Aluminium Oxide _______ Method 1: Working with ratios THE PROCESS FOR WRITING FORMULAE Example 1. Work out the ratio of ions Write the formula for Calcium that will cause a balance 1 Ca2+ HCO3 - of positive & negative bicarbonate 1 : 2 charges 2. Writing it out without the charges 2 Ca HCO3 3. Put the subscripts in place to reflect the 3 Ca(HCO3)2 ratio Thursday, 16 September 2010
  21. 21. WRITING FORMULAE Copy Examples Use your table of ions to write formluae for the following ionic compounds: Sodium Fluoride _____________ Magnesium Oxide __________ Sodium Oxide _______________ Zinc Chloride _____________ Lead Nitrate ______________ Potassium Sulphate ____________ Calcium Hydrogen Carbonate __________ Aluminium Oxide _______ Method 1: Working with ratios THE PROCESS FOR WRITING FORMULAE Example 1. Work out the ratio of ions Write the formula for Calcium that will cause a balance 1 Ca2+ HCO3 - of positive & negative bicarbonate 1 : 2 charges 2. Writing it out without the charges 2 Ca HCO3 3. Put the subscripts in place to reflect the 3 Ca(HCO3)2 ratio Thursday, 16 September 2010
  22. 22. WRITING FORMULAE Copy Examples Use your table of ions to write formluae for the following ionic compounds: Sodium Fluoride _____________ Magnesium Oxide __________ Sodium Oxide _______________ Zinc Chloride _____________ Lead Nitrate ______________ Potassium Sulphate ____________ Calcium Hydrogen Carbonate __________ Aluminium Oxide _______ Method 1: Working with ratios THE PROCESS FOR WRITING FORMULAE Example 1. Work out the ratio of ions Write the formula for Calcium that will cause a balance 1 Ca2+ HCO3 - of positive & negative bicarbonate 1 : 2 charges 2. Writing it out without the charges 2 Ca HCO3 3. Put the subscripts in place to reflect the 3 Ca(HCO3)2 ratio Note The “1” is never shown as a subscript Ions that are made up of groups must be bracketed if the subscript is “2” or more. Thursday, 16 September 2010
  23. 23. WRITING FORMULAE Copy Examples Use your table of ions to write formluae for the following ionic compounds: NaF Sodium Fluoride _____________ Magnesium Oxide __________ Sodium Oxide _______________ Zinc Chloride _____________ Lead Nitrate ______________ Potassium Sulphate ____________ Calcium Hydrogen Carbonate __________ Aluminium Oxide _______ Method 1: Working with ratios THE PROCESS FOR WRITING FORMULAE Example 1. Work out the ratio of ions Write the formula for Calcium that will cause a balance 1 Ca2+ HCO3 - of positive & negative bicarbonate 1 : 2 charges 2. Writing it out without the charges 2 Ca HCO3 3. Put the subscripts in place to reflect the 3 Ca(HCO3)2 ratio Note The “1” is never shown as a subscript Ions that are made up of groups must be bracketed if the subscript is “2” or more. Thursday, 16 September 2010
  24. 24. WRITING FORMULAE Copy Examples Use your table of ions to write formluae for the following ionic compounds: NaF Sodium Fluoride _____________ Magnesium Oxide __________ MgO Sodium Oxide _______________ Zinc Chloride _____________ Lead Nitrate ______________ Potassium Sulphate ____________ Calcium Hydrogen Carbonate __________ Aluminium Oxide _______ Method 1: Working with ratios THE PROCESS FOR WRITING FORMULAE Example 1. Work out the ratio of ions Write the formula for Calcium that will cause a balance 1 Ca2+ HCO3 - of positive & negative bicarbonate 1 : 2 charges 2. Writing it out without the charges 2 Ca HCO3 3. Put the subscripts in place to reflect the 3 Ca(HCO3)2 ratio Note The “1” is never shown as a subscript Ions that are made up of groups must be bracketed if the subscript is “2” or more. Thursday, 16 September 2010
  25. 25. WRITING FORMULAE Copy Examples Use your table of ions to write formluae for the following ionic compounds: NaF Sodium Fluoride _____________ Magnesium Oxide __________ MgO Sodium Oxide Na2O _______________ Zinc Chloride _____________ Lead Nitrate ______________ Potassium Sulphate ____________ Calcium Hydrogen Carbonate __________ Aluminium Oxide _______ Method 1: Working with ratios THE PROCESS FOR WRITING FORMULAE Example 1. Work out the ratio of ions Write the formula for Calcium that will cause a balance 1 Ca2+ HCO3 - of positive & negative bicarbonate 1 : 2 charges 2. Writing it out without the charges 2 Ca HCO3 3. Put the subscripts in place to reflect the 3 Ca(HCO3)2 ratio Note The “1” is never shown as a subscript Ions that are made up of groups must be bracketed if the subscript is “2” or more. Thursday, 16 September 2010
  26. 26. WRITING FORMULAE Copy Examples Use your table of ions to write formluae for the following ionic compounds: NaF Sodium Fluoride _____________ Magnesium Oxide __________ MgO Sodium Oxide Na2O _______________ ZnCl2 Zinc Chloride _____________ Lead Nitrate ______________ Potassium Sulphate ____________ Calcium Hydrogen Carbonate __________ Aluminium Oxide _______ Method 1: Working with ratios THE PROCESS FOR WRITING FORMULAE Example 1. Work out the ratio of ions Write the formula for Calcium that will cause a balance 1 Ca2+ HCO3 - of positive & negative bicarbonate 1 : 2 charges 2. Writing it out without the charges 2 Ca HCO3 3. Put the subscripts in place to reflect the 3 Ca(HCO3)2 ratio Note The “1” is never shown as a subscript Ions that are made up of groups must be bracketed if the subscript is “2” or more. Thursday, 16 September 2010
  27. 27. WRITING FORMULAE Copy Examples Use your table of ions to write formluae for the following ionic compounds: NaF Sodium Fluoride _____________ Magnesium Oxide __________ MgO Sodium Oxide Na2O ZnCl2 _______________ Zinc Chloride _____________ Pb(NO3)2 Lead Nitrate ______________ Potassium Sulphate ____________ Calcium Hydrogen Carbonate __________ Aluminium Oxide _______ Method 1: Working with ratios THE PROCESS FOR WRITING FORMULAE Example 1. Work out the ratio of ions Write the formula for Calcium that will cause a balance 1 Ca2+ HCO3 - of positive & negative bicarbonate 1 : 2 charges 2. Writing it out without the charges 2 Ca HCO3 3. Put the subscripts in place to reflect the 3 Ca(HCO3)2 ratio Note The “1” is never shown as a subscript Ions that are made up of groups must be bracketed if the subscript is “2” or more. Thursday, 16 September 2010
  28. 28. WRITING FORMULAE Copy Examples Use your table of ions to write formluae for the following ionic compounds: NaF Sodium Fluoride _____________ Magnesium Oxide __________ MgO Sodium Oxide Na2O ZnCl2 _______________ Zinc Chloride _____________ Pb(NO3)2 Lead Nitrate ______________ K2SO4 Potassium Sulphate ____________ Calcium Hydrogen Carbonate __________ Aluminium Oxide _______ Method 1: Working with ratios THE PROCESS FOR WRITING FORMULAE Example 1. Work out the ratio of ions Write the formula for Calcium that will cause a balance 1 Ca2+ HCO3 - of positive & negative bicarbonate 1 : 2 charges 2. Writing it out without the charges 2 Ca HCO3 3. Put the subscripts in place to reflect the 3 Ca(HCO3)2 ratio Note The “1” is never shown as a subscript Ions that are made up of groups must be bracketed if the subscript is “2” or more. Thursday, 16 September 2010
  29. 29. WRITING FORMULAE Copy Examples Use your table of ions to write formluae for the following ionic compounds: NaF Sodium Fluoride _____________ Magnesium Oxide __________ MgO Sodium Oxide Na2O ZnCl2 _______________ Zinc Chloride _____________ Pb(NO3)2 Lead Nitrate ______________ K2SO4 Potassium Sulphate ____________ Ca(HCO3)2 Calcium Hydrogen Carbonate __________ Aluminium Oxide _______ Method 1: Working with ratios THE PROCESS FOR WRITING FORMULAE Example 1. Work out the ratio of ions Write the formula for Calcium that will cause a balance 1 Ca2+ HCO3 - of positive & negative bicarbonate 1 : 2 charges 2. Writing it out without the charges 2 Ca HCO3 3. Put the subscripts in place to reflect the 3 Ca(HCO3)2 ratio Note The “1” is never shown as a subscript Ions that are made up of groups must be bracketed if the subscript is “2” or more. Thursday, 16 September 2010
  30. 30. WRITING FORMULAE Copy Examples Use your table of ions to write formluae for the following ionic compounds: NaF Sodium Fluoride _____________ Magnesium Oxide __________ MgO Sodium Oxide Na2O ZnCl2 _______________ Zinc Chloride _____________ Pb(NO3)2 Lead Nitrate ______________ K2SO4 Potassium Sulphate ____________ Ca(HCO3)2 Al2O3 Calcium Hydrogen Carbonate __________ Aluminium Oxide _______ Method 1: Working with ratios THE PROCESS FOR WRITING FORMULAE Example 1. Work out the ratio of ions Write the formula for Calcium that will cause a balance 1 Ca2+ HCO3 - of positive & negative bicarbonate 1 : 2 charges 2. Writing it out without the charges 2 Ca HCO3 3. Put the subscripts in place to reflect the 3 Ca(HCO3)2 ratio Note The “1” is never shown as a subscript Ions that are made up of groups must be bracketed if the subscript is “2” or more. Thursday, 16 September 2010
  31. 31. Copy Method 2: The swop and drop method 1. Write the ions down next to each other. 2. Drop each number down (without the charge) and swop it to make the subscript of the other element Example Write the formula for Aluminium Oxide The valencies If you are given the formula then think backwards to determine the valencies. Thursday, 16 September 2010
  32. 32. Copy Method 2: The swop and drop method 1. Write the ions down next to each other. 2. Drop each number down (without the charge) and swop it to make the subscript of the other element Example Write the formula for Aluminium Oxide The valencies 1 Al O 3+ 2- If you are given the formula then think backwards to determine the valencies. Thursday, 16 September 2010
  33. 33. Copy Method 2: The swop and drop method 1. Write the ions down next to each other. 2. Drop each number down (without the charge) and swop it to make the subscript of the other element Example Write the formula for Aluminium Oxide The valencies 1 Al O 3+ 2- If you are given the formula then think backwards to determine the valencies. Thursday, 16 September 2010
  34. 34. Copy Method 2: The swop and drop method 1. Write the ions down next to each other. 2. Drop each number down (without the charge) and swop it to make the subscript of the other element Example Write the formula for Aluminium Oxide The valencies 1 Al O 3+ 2- If you are given the formula then think backwards to determine the valencies. Thursday, 16 September 2010
  35. 35. Copy Method 2: The swop and drop method 1. Write the ions down next to each other. 2. Drop each number down (without the charge) and swop it to make the subscript of the other element Example Write the formula for Aluminium Oxide The valencies 1 Al O 3+ 2- 2 Al2O3 If you are given the formula then think backwards to determine the valencies. Thursday, 16 September 2010
  36. 36. FORMULAE FOR SIMPLE IONS +1 +2 +3 _,, -1 H* Mg2* Al3+ c1- gz- hydrogen magnesium aluminium chloride oxide Li* Ca2* Fe3* oH- COr'- lithium calcium iron(III) hydroxide carbonate Na+ Fe2* No,* Soo'- sodium iron(II) nitrate sulfate K+ Cu2* HCO3- potasslum copper(II) hydrogen carbonate PO43- Zn2* Phosphate zinc Pb2+ lead Thursday, 16 September 2010
  37. 37. UTILIZING BONDING POTENTIAL Valency can be shown using bonding symbols Examples Phosphorus has a valency of 3 and so has the potential to form 3 covalent bonds. Sometimes written: P Thursday, 16 September 2010
  38. 38. EQUATIONS INTERACTIVE Thursday, 16 September 2010
  39. 39. Wri$ng  Chemical  Equa$ons Chemical  reac$ons  are  the  chemists  shorthand  way   of  describing  chemical  reac$ons. Thursday, 16 September 2010
  40. 40. Wri$ng  Chemical  Equa$ons Chemical  reac$ons  are  the  chemists  shorthand  way   of  describing  chemical  reac$ons. The  equa$ons  can  be  either: Thursday, 16 September 2010
  41. 41. Wri$ng  Chemical  Equa$ons Chemical  reac$ons  are  the  chemists  shorthand  way   of  describing  chemical  reac$ons. The  equa$ons  can  be  either:   1.  Word  equa$ons     Thursday, 16 September 2010
  42. 42. Wri$ng  Chemical  Equa$ons Chemical  reac$ons  are  the  chemists  shorthand  way   of  describing  chemical  reac$ons. The  equa$ons  can  be  either:   1.  Word  equa$ons     or     2.  Balanced  symbol  equa$ons Thursday, 16 September 2010
  43. 43. Wri$ng  Chemical  Equa$ons Chemical  reac$ons  are  the  chemists  shorthand  way   of  describing  chemical  reac$ons. The  equa$ons  can  be  either:   1.  Word  equa$ons     or     2.  Balanced  symbol  equa$ons Thursday, 16 September 2010
  44. 44. Wri$ng  Chemical  Equa$ons Chemical  reac$ons  are  the  chemists  shorthand  way   of  describing  chemical  reac$ons. The  equa$ons  can  be  either:   1.  Word  equa$ons     or     2.  Balanced  symbol  equa$ons For  both  types  all  reactants  (star$ng  substances)  and   products  of  the  reac$on  (end  substances)  must  be   correctly    iden$fied.   Thursday, 16 September 2010
  45. 45. Symbol  Equa$ons Each  reactant  and  product  is  represented  by  a   formula  that  represents  the  smallest  par$cle  that  can   take  part  in  the  reac$on. Thursday, 16 September 2010
  46. 46. Symbol  Equa$ons Each  reactant  and  product  is  represented  by  a   formula  that  represents  the  smallest  par$cle  that  can   take  part  in  the  reac$on. The  formula  of  any  solid  element  is  simply  the   symbol  (i.e.  for  one  atom) Thursday, 16 September 2010
  47. 47. Symbol  Equa$ons Each  reactant  and  product  is  represented  by  a   formula  that  represents  the  smallest  par$cle  that  can   take  part  in  the  reac$on. The  formula  of  any  solid  element  is  simply  the   symbol  (i.e.  for  one  atom) Thursday, 16 September 2010
  48. 48. Symbol  Equa$ons Each  reactant  and  product  is  represented  by  a   formula  that  represents  the  smallest  par$cle  that  can   take  part  in  the  reac$on. The  formula  of  any  solid  element  is  simply  the   symbol  (i.e.  for  one  atom)   e.g.  Magnesium  Metal      use  Mg Thursday, 16 September 2010
  49. 49. Thursday, 16 September 2010
  50. 50. Balancing  Equa$ons Equa$ons  must  be  “balanced”.  This  is  based  on  the   fact  that  during  a  reac$on  no  atoms  are  destroyed,   nor  are  any  new  atoms  created. Therefore  the  numbers  of  each  type  of  atom  in  the   reactants  must  equal  the  number  of  each  type  of   atom  in  the  products.   Thursday, 16 September 2010
  51. 51. Rules: Thursday, 16 September 2010
  52. 52. Rules: 1. Name  all  of  the  reactants  and  products Thursday, 16 September 2010
  53. 53. Rules: 1. Name  all  of  the  reactants  and  products 2. Write  the  correct  formula  for  each  substance   involved. Thursday, 16 September 2010
  54. 54. Rules: 1. Name  all  of  the  reactants  and  products 2. Write  the  correct  formula  for  each  substance   involved. 3.  Balance  so  the  number  of  each  type  of  atoms   remains  the  same  during  the  reac$on.  Formula  can   not  be  changed,  so  balancing  must  be  done  by   changing  the  number  of  par$cles  involved. Thursday, 16 September 2010
  55. 55. EQUATION 1 Potassium        +          Chlorine  (g)                  Potassium  chloride                    K                          +              Cl2                                                                KCl            2  K                          +              Cl2                                                          2  KCl i.e.  2  atoms  of  potassium  react  with  1  molecule  of   chlorine  to  produce  2  units  of  potassium  chloride.   Why  “units”? Thursday, 16 September 2010
  56. 56. EQUATION 1 Potassium        +          Chlorine  (g)                  Potassium  chloride                    K                          +              Cl2                                                                KCl            2  K                          +              Cl2                                                          2  KCl i.e.  2  atoms  of  potassium  react  with  1  molecule  of   chlorine  to  produce  2  units  of  potassium  chloride.   Why  “units”? Thursday, 16 September 2010
  57. 57. EQUATION 1 Potassium        +          Chlorine  (g)                  Potassium  chloride                    K                          +              Cl2                                                                KCl Thursday, 16 September 2010
  58. 58. EQUATION 1 Potassium        +          Chlorine  (g)                  Potassium  chloride                    K                          +              Cl2                                                                KCl Thursday, 16 September 2010
  59. 59. EQUATION 1 Potassium        +          Chlorine  (g)                  Potassium  chloride                    K                          +              Cl2                                                                KCl            2  K                          +              Cl2                                                          2  KCl Thursday, 16 September 2010
  60. 60. EQUATION 1 Potassium        +          Chlorine  (g)                  Potassium  chloride                    K                          +              Cl2                                                                KCl            2  K                          +              Cl2                                                          2  KCl Thursday, 16 September 2010
  61. 61. EQUATION 1 Potassium        +          Chlorine  (g)                  Potassium  chloride                    K                          +              Cl2                                                                KCl            2  K                          +              Cl2                                                          2  KCl i.e.  2  atoms  of  potassium  react  with  1  molecule  of   chlorine  to  produce  2  units  of  potassium  chloride.   Thursday, 16 September 2010
  62. 62. EQUATION 1 Potassium        +          Chlorine  (g)                  Potassium  chloride                    K                          +              Cl2                                                                KCl            2  K                          +              Cl2                                                          2  KCl i.e.  2  atoms  of  potassium  react  with  1  molecule  of   chlorine  to  produce  2  units  of  potassium  chloride.   Why  “units”? Thursday, 16 September 2010
  63. 63. EQUATION 2            Sodium              +      Oxygen  (g)                                          Sodium  oxide              Na                          +              O2                                                                Na2O        4  Na                          +            O2                                                              2  Na2O               Thursday, 16 September 2010
  64. 64. EQUATION 2            Sodium              +      Oxygen  (g)                                          Sodium  oxide              Na                          +              O2                                                                Na2O        4  Na                          +            O2                                                              2  Na2O               Thursday, 16 September 2010
  65. 65. EQUATION 2            Sodium              +      Oxygen  (g)                                          Sodium  oxide              Na                          +              O2                                                                Na2O Thursday, 16 September 2010
  66. 66. EQUATION 2            Sodium              +      Oxygen  (g)                                          Sodium  oxide              Na                          +              O2                                                                Na2O Thursday, 16 September 2010
  67. 67. EQUATION 2            Sodium              +      Oxygen  (g)                                          Sodium  oxide              Na                          +              O2                                                                Na2O        4  Na                          +            O2                                                              2  Na2O               Thursday, 16 September 2010
  68. 68. EQUATION 3 Sodium              +      sulfuric                                  sodium      +      water   hydroxide                acid                                              sulfate    NaOH                +    H2SO4                                      Na2SO4      +      H2O  2  NaOH            +    H2SO4                                      Na2SO4      +    2  H2O Thursday, 16 September 2010
  69. 69. EQUATION 3 Sodium              +      sulfuric                                  sodium      +      water   hydroxide                acid                                              sulfate    NaOH                +    H2SO4                                      Na2SO4      +      H2O  2  NaOH            +    H2SO4                                      Na2SO4      +    2  H2O Thursday, 16 September 2010
  70. 70. EQUATION 3 Sodium              +      sulfuric                                  sodium      +      water   hydroxide                acid                                              sulfate    NaOH                +    H2SO4                                      Na2SO4      +      H2O Thursday, 16 September 2010
  71. 71. EQUATION 3 Sodium              +      sulfuric                                  sodium      +      water   hydroxide                acid                                              sulfate    NaOH                +    H2SO4                                      Na2SO4      +      H2O Thursday, 16 September 2010
  72. 72. EQUATION 3 Sodium              +      sulfuric                                  sodium      +      water   hydroxide                acid                                              sulfate    NaOH                +    H2SO4                                      Na2SO4      +      H2O  2  NaOH            +    H2SO4                                      Na2SO4      +    2  H2O Thursday, 16 September 2010
  73. 73. ACID/CARBONATE REACTION EQUATION 4 Calcium        +    hydrochloric                          calcium      +      carbon      +      water carbonate          acid                            chloride              dioxide     CaCO3        +      HCl                                                CaCl2          +    CO2          +        H2O      CaCO3      +    2  HCl                                          CaCl2          +        CO2          +      H2O   Thursday, 16 September 2010
  74. 74. ACID/CARBONATE REACTION EQUATION 4 Calcium        +    hydrochloric                          calcium      +      carbon      +      water carbonate          acid                            chloride              dioxide     CaCO3        +      HCl                                                CaCl2          +    CO2          +        H2O      CaCO3      +    2  HCl                                          CaCl2          +        CO2          +      H2O   Thursday, 16 September 2010
  75. 75. ACID/CARBONATE REACTION EQUATION 4 Calcium        +    hydrochloric                          calcium      +      carbon      +      water carbonate          acid                            chloride              dioxide     CaCO3        +      HCl                                                CaCl2          +    CO2          +        H2O   Thursday, 16 September 2010
  76. 76. ACID/CARBONATE REACTION EQUATION 4 Calcium        +    hydrochloric                          calcium      +      carbon      +      water carbonate          acid                            chloride              dioxide     CaCO3        +      HCl                                                CaCl2          +    CO2          +        H2O     Thursday, 16 September 2010
  77. 77. ACID/CARBONATE REACTION EQUATION 4 Calcium        +    hydrochloric                          calcium      +      carbon      +      water carbonate          acid                            chloride              dioxide     CaCO3        +      HCl                                                CaCl2          +    CO2          +        H2O      CaCO3      +    2  HCl                                          CaCl2          +        CO2          +      H2O   Thursday, 16 September 2010
  78. 78. EQUATION 5 sodium        +            sulfuric                          sodium      +      carbon      +      water bicarbonate          acid                            sulfate                    dioxide      NaHCO3    +    H2SO4                                  Na2SO4    +    CO2      +      H2O     2  NaHCO3    +    H2SO4                                Na2SO4  +  2  CO2  +    2  H2O     Thursday, 16 September 2010
  79. 79. EQUATION 5 sodium        +            sulfuric                          sodium      +      carbon      +      water bicarbonate          acid                            sulfate                    dioxide      NaHCO3    +    H2SO4                                  Na2SO4    +    CO2      +      H2O     2  NaHCO3    +    H2SO4                                Na2SO4  +  2  CO2  +    2  H2O     Thursday, 16 September 2010
  80. 80. EQUATION 5 sodium        +            sulfuric                          sodium      +      carbon      +      water bicarbonate          acid                            sulfate                    dioxide      NaHCO3    +    H2SO4                                  Na2SO4    +    CO2      +      H2O   Thursday, 16 September 2010
  81. 81. EQUATION 5 sodium        +            sulfuric                          sodium      +      carbon      +      water bicarbonate          acid                            sulfate                    dioxide      NaHCO3    +    H2SO4                                  Na2SO4    +    CO2      +      H2O     Thursday, 16 September 2010
  82. 82. EQUATION 5 sodium        +            sulfuric                          sodium      +      carbon      +      water bicarbonate          acid                            sulfate                    dioxide      NaHCO3    +    H2SO4                                  Na2SO4    +    CO2      +      H2O     2  NaHCO3    +    H2SO4                                Na2SO4  +  2  CO2  +    2  H2O   Thursday, 16 September 2010
  83. 83. EQUATION 6 Ferric  oxide      +      carbon                                      iron  +  carbon  monoxide        Fe2O3                    +                  C       Fe            +                          CO          Fe2O3                  +            3  C                  2  Fe            +                  3  CO     Thursday, 16 September 2010
  84. 84. EQUATION 6 Ferric  oxide      +      carbon                                      iron  +  carbon  monoxide        Fe2O3                    +                  C       Fe            +                          CO          Fe2O3                  +            3  C                  2  Fe            +                  3  CO     Thursday, 16 September 2010
  85. 85. EQUATION 6 Ferric  oxide      +      carbon                                      iron  +  carbon  monoxide        Fe2O3                    +                  C       Fe            +                          CO Thursday, 16 September 2010
  86. 86. EQUATION 6 Ferric  oxide      +      carbon                                      iron  +  carbon  monoxide        Fe2O3                    +                  C       Fe            +                          CO          Fe2O3                  +            3  C                  2  Fe            +                  3  CO Thursday, 16 September 2010
  87. 87. EQUATION 7 Magnesium      +      steam                              magnesium  +    hydrogen                                                                                                                  hydroxide                            gas                Mg                    +            H2O        Mg(OH)2              +            H2                Mg                    +      2  H2O        Mg(OH)2              +            H2   Thursday, 16 September 2010
  88. 88. EQUATION 7 Magnesium      +      steam                              magnesium  +    hydrogen                                                                                                                  hydroxide                            gas                Mg                    +            H2O        Mg(OH)2              +            H2                Mg                    +      2  H2O        Mg(OH)2              +            H2   Thursday, 16 September 2010
  89. 89. EQUATION 7 Magnesium      +      steam                              magnesium  +    hydrogen                                                                                                                  hydroxide                            gas                Mg                    +            H2O        Mg(OH)2              +            H2 Thursday, 16 September 2010
  90. 90. EQUATION 7 Magnesium      +      steam                              magnesium  +    hydrogen                                                                                                                  hydroxide                            gas                Mg                    +            H2O        Mg(OH)2              +            H2 Thursday, 16 September 2010
  91. 91. EQUATION 7 Magnesium      +      steam                              magnesium  +    hydrogen                                                                                                                  hydroxide                            gas                Mg                    +            H2O        Mg(OH)2              +            H2                Mg                    +      2  H2O        Mg(OH)2              +            H2 Thursday, 16 September 2010
  92. 92. EQUATION 8 zinc      +      sulfuric         zinc              +          hydrogen                                  acid                                                  sulfate                              gas Thursday, 16 September 2010
  93. 93. EQUATION 8 zinc      +      sulfuric         zinc              +          hydrogen                                  acid                                                  sulfate                              gas      Zn      +        H2SO4       ZnSO4        +                  H2 Thursday, 16 September 2010
  94. 94. EQUATION 8 zinc      +      sulfuric         zinc              +          hydrogen                                  acid                                                  sulfate                              gas      Zn      +        H2SO4       ZnSO4        +                  H2                 (balanced,   no  modifica2on  needed) Thursday, 16 September 2010
  95. 95. EQUATION 9 Aluminium      +      oxygen     aluminium  oxide                Al                      +      O2                                                              Al2O3              4  Al                    +        3  O2                                                      2  Al2O3   Thursday, 16 September 2010
  96. 96. EQUATION 9 Aluminium      +      oxygen     aluminium  oxide                Al                      +      O2                                                              Al2O3              4  Al                    +        3  O2                                                      2  Al2O3   Thursday, 16 September 2010
  97. 97. EQUATION 9 Aluminium      +      oxygen     aluminium  oxide                Al                      +      O2                                                              Al2O3 Thursday, 16 September 2010
  98. 98. EQUATION 9 Aluminium      +      oxygen     aluminium  oxide                Al                      +      O2                                                              Al2O3     Thursday, 16 September 2010
  99. 99. EQUATION 9 Aluminium      +      oxygen     aluminium  oxide                Al                      +      O2                                                              Al2O3              4  Al                    +        3  O2                                                      2  Al2O3   Thursday, 16 September 2010
  100. 100. NOTES Thursday, 16 September 2010
  101. 101. OXIDATION - REDUCTION Thursday, 16 September 2010
  102. 102. METALS ARE REDUCING AGENTS Thursday, 16 September 2010
  103. 103. Copy OXIDATION and REDUCTION Definitions “LEO the lion Loss of Electrons is Oxidation goes GER” Gain of Electrons is Reduction • Oxidation is also the addition of oxygen or the removal of hydrogen. • Reduction is the removal of oxygen or the addition of hydrogen. • Oxidation and reduction always occur together Oxidants & Reductants • An oxidant is a substance that causes oxidation and is itself reduced. Example: In the reaction between Zinc and Oxygen, Oxygen is the oxidant. It has caused Zinc to gain oxygen. Zinc Oxide is produced. • A reductant is a substance that causes reduction and is itself oxidised. Example: In the reaction between Hydrogen and Copper oxide, Hydrogen is the reductant. It has caused Copper oxide to lose oxygen. Copper is produced. Thursday, 16 September 2010
  104. 104. Half equations Copy REDOX REACTION TYPES Simple electron transfer Reactions that involve atoms losing or gaining electrons. Ions become atoms, atoms become ions. Example 1 Burning magnesium in oxygen - final equation: 2Mg + O2 --> 2MgO Thursday, 16 September 2010
  105. 105. Half equations Copy REDOX REACTION TYPES Simple electron transfer Reactions that involve atoms losing or gaining electrons. Ions become atoms, atoms become ions. Example 1 Burning magnesium in oxygen - final equation: 2Mg + O2 --> 2MgO Magnesium loses electrons to form ions Thursday, 16 September 2010
  106. 106. Half equations Copy REDOX REACTION TYPES Simple electron transfer Reactions that involve atoms losing or gaining electrons. Ions become atoms, atoms become ions. Example 1 Burning magnesium in oxygen - final equation: 2Mg + O2 --> 2MgO Magnesium loses electrons to form ions (Mg --> Mg2+ + 2e-) x 2 Thursday, 16 September 2010
  107. 107. Half equations Copy REDOX REACTION TYPES Simple electron transfer Reactions that involve atoms losing or gaining electrons. Ions become atoms, atoms become ions. Example 1 Burning magnesium in oxygen - final equation: 2Mg + O2 --> 2MgO Magnesium loses electrons to form ions (Mg --> Mg2+ + 2e-) x 2 Oxygen gains electrons to form ions Thursday, 16 September 2010
  108. 108. Half equations Copy REDOX REACTION TYPES Simple electron transfer Reactions that involve atoms losing or gaining electrons. Ions become atoms, atoms become ions. Example 1 Burning magnesium in oxygen - final equation: 2Mg + O2 --> 2MgO Magnesium loses electrons to form ions (Mg --> Mg2+ + 2e-) x 2 Oxygen gains electrons to form ions O2 + 4e- --> 2O2- Thursday, 16 September 2010
  109. 109. Half equations Copy REDOX REACTION TYPES Simple electron transfer Reactions that involve atoms losing or gaining electrons. Ions become atoms, atoms become ions. Example 1 Burning magnesium in oxygen - final equation: 2Mg + O2 --> 2MgO Magnesium loses electrons to form ions (Mg --> Mg2+ + 2e-) x 2 Oxygen gains electrons to form ions O2 + 4e- --> 2O2- Thursday, 16 September 2010
  110. 110. Half equations Copy REDOX REACTION TYPES Simple electron transfer Reactions that involve atoms losing or gaining electrons. Ions become atoms, atoms become ions. Example 1 Burning magnesium in oxygen - final equation: 2Mg + O2 --> 2MgO Magnesium loses electrons to form ions (Mg --> Mg2+ + 2e-) x 2 Oxygen gains electrons to form ions O2 + 4e- --> 2O2- These equations can only be added once the first equation has been doubled. This ensures that the number of electrons gained in the reaction equals the number of electrons lost. Thursday, 16 September 2010
  111. 111. Half equations Copy REDOX REACTION TYPES Simple electron transfer Reactions that involve atoms losing or gaining electrons. Ions become atoms, atoms become ions. Example 1 Burning magnesium in oxygen - final equation: 2Mg + O2 --> 2MgO Magnesium loses electrons to form ions (Mg --> Mg2+ + 2e-) x 2 Oxygen gains electrons to form ions O2 + 4e- --> 2O2- These equations can only be added once the first equation has been doubled. This ensures that the number of electrons gained in the reaction equals the number of electrons lost. Adding the two equations and cancelling the charges gives the final equation. The final equation describes both the reduction and oxidation together: Thursday, 16 September 2010
  112. 112. Half equations Copy REDOX REACTION TYPES Simple electron transfer Reactions that involve atoms losing or gaining electrons. Ions become atoms, atoms become ions. Example 1 Burning magnesium in oxygen - final equation: 2Mg + O2 --> 2MgO Magnesium loses electrons to form ions (Mg --> Mg2+ + 2e-) x 2 Oxygen gains electrons to form ions O2 + 4e- --> 2O2- These equations can only be added once the first equation has been doubled. This ensures that the number of electrons gained in the reaction equals the number of electrons lost. Adding the two equations and cancelling the charges gives the final equation. The final equation describes both the reduction and oxidation together: 2Mg + O2 + 4e- --> 2 Mg2+ + 2O2- + 4e- Thursday, 16 September 2010
  113. 113. Half equations Copy REDOX REACTION TYPES Simple electron transfer Reactions that involve atoms losing or gaining electrons. Ions become atoms, atoms become ions. Example 1 Burning magnesium in oxygen - final equation: 2Mg + O2 --> 2MgO Magnesium loses electrons to form ions (Mg --> Mg2+ + 2e-) x 2 Oxygen gains electrons to form ions O2 + 4e- --> 2O2- These equations can only be added once the first equation has been doubled. This ensures that the number of electrons gained in the reaction equals the number of electrons lost. Adding the two equations and cancelling the charges gives the final equation. The final equation describes both the reduction and oxidation together: 2Mg + O2 + 4e- --> 2 Mg2+ + 2O2- + 4e- 2Mg + O2 --> 2MgO Thursday, 16 September 2010
  114. 114. Spectator ions Copy Example 2 Zinc powder added to Copper Sulphate solution. Sulphate ion is a spectator ion. - final equation: Zn + CuSO4 --> Cu + ZnSO4 Zn --> Zn2+ + 2e- Oxidation - half equations: Cu2+ + 2e- --> Cu Reduction Zn + Cu2+ + 2e- --> Zn2+ + Cu + 2e- - Adding the two half equations and cancelling out the charges gives the final equation (above). In Summary Half equations are used to show how electrons are lost and gained in redox reactions (reactions involving reduction and oxidation) Thursday, 16 September 2010
  115. 115. Copy Example 3 (class prac) A bright steel nail is placed in 2 mL of copper sulphate solution (0.1 molL-1) in a test tube. Observation: - half equations: - final equation: Example 4 (class prac) A 2 cm strip of Magnesium ribbon is placed in 2 mL of Lead nitrate solution in a test tube. Observation: - half equations: - final equation: Thursday, 16 September 2010
  116. 116. Copy Example 5 (class prac) A 2 cm strip of Magnesium ribbon is placed in 2 mL of Silver nitrate solution in a test tube. Observation: - half equations: - final equation: Example 6 (class prac) A small (1 - 2 cm strip) of Copper foil is placed in 2 mL of Lead nitrate solution in a test tube. Observation: - half equations: - final equation: More redox reaction pracs (ABA P34: “Reactions 4 & 5) Thursday, 16 September 2010
  117. 117. WHEN DISCUSSING CHEMISTRY OF REDOX REACTION ALWAYS INCLUDE A DISCUSSION OF ELECTRON TRANSFER IN ADDITION TO APPLICATION OF OTHER PRINCIPLES OF REDUCTION/OXIDATION Thursday, 16 September 2010
  118. 118. PRECIPITATION Thursday, 16 September 2010
  119. 119. Calcium Chloride solution (clear & colourless) added to Silver Nitrate solution (clear & colourless) white precipitate. Thursday, 16 September 2010
  120. 120. Silver Nitrate solution (clear & colourless) added to Sodium Sulphide solution (clear & colourless) black precipitate Thursday, 16 September 2010
  121. 121. Copy WHAT IS A PRECIPITATE? A precipitate may form when one ionic solution is added to another. It is not possible to see through a solution when a precipitate forms in it. The solution becomes cloudy. The precipitate will eventually settle to the bottom of the container. Definition A precipitation reaction has occurred when a solid forms as a result of a reaction between two solutions. The solid forms because it is an insoluble product of the reaction. Thursday, 16 September 2010
  122. 122. HOW PRECIPITATES FORM Example A solution of Copper Sulphate is added to a solution of Sodium Carbonate. Copper ions spread through the water The copper sulphate solution contains: Sulphate ions spread through the water Sodium ions spread through the water The sodium carbonate solution contains: Carbonate ions spread through the water Forces of attraction between the Copper ions and Sulphate ions are weak enough for the water molecules to get between the ions. The same is true for the sodium and carbonate ions. The same cannot be said for the Copper ions that collide with the Carbonate ions in this mixture. A bond forms that is stronger than the attraction that water has for the ions and so a precipitate is formed. The Sodium and sulphate ions are dispersed and free to move amongst the water molecules. They are spectator ions. Copper Sulphate + Sodium Carbonate --> Copper Carbonate + Sodium Sulphate Ion equation: Complete formula equation: Thursday, 16 September 2010
  123. 123. SOLUBILITY RULES “You can predict whether or not a compound is soluble by using the following simple rules:” 1. All nitrates are soluble. 2. All group 1 metal compounds and ammonium compounds are soluble. 3. All chlorides are soluble except for silver chloride and lead chloride 4. All sulfates are soluble except for barium sulfate and lead sulfate. 5. All carbonates are insoluble except group 1 and ammonium compounds 6. All hydroxides and oxides are insoluble (exception Sodium & Potassium) Thursday, 16 September 2010
  124. 124. Thursday, 16 September 2010
  125. 125. Thursday, 16 September 2010
  126. 126. Thursday, 16 September 2010
  127. 127. THERMAL DECOMPOSITION Thursday, 16 September 2010
  128. 128. EQUATIONS OF DECOMPOSITION REACTIONS A decomposition reaction is one in which a compound breaks down to form simpler compounds. A thermal decomposition requires heat. Word equations for simple decomposition reactions 1. The thermal decomposition of carbonates, Eg ... Calcium Carbonate --> Calcium Oxide + Carbon Dioxide Copper Carbonate --> Copper Oxide + Carbon Dioxide 2. The thermal decomposition of sodium bicarbonate, Eg... Sodium Bicarbonate --> Sodium Carbonate + Water + Carbon Dioxide 3. The decomposition of hydroxides Copper Hydroxide --> Copper Oxide + Water Note Not all metal carbonates, hydrogen carbonates and hydroxides will decompose on heating. Position on the reactivity series is an important factor Thursday, 16 September 2010
  129. 129. REACTIVITY SERIES OF METALS Most reactive K Na Li In a simple electron exchange reaction (redox), a metal higher in the series will Ca donate electrons to one that is lower in Mg the series Al Zn Example Fe Sn Zn(s) + CuSO4(aq) ---> ZnSO4(aq) + Cu(s) Pb Grey Blue Colourless orange-brown Cu Hg Ag Least reactive Au Thursday, 16 September 2010
  130. 130. CALCULATIONS Thursday, 16 September 2010
  131. 131. ATOMIC & MOLECULAR MASSES The mole Consider the formation of Carbon Monoxide: C + O ---> CO This is often understood as meaning “1 atom of C” + “1 atom of O” ---> “1 molecule of CO” But working with single atoms when you are performing calculations involving mass means working with masses that are too small. The chemist needs to find a larger unit so that masses in calculations are realistic. This unit is called the mole. A mole is a unit that consists of 6.023 x 1023 objects. Atomic masses “This means that 1 mole of hydrogen atomic 1 (6.023 x 1023 atoms) has a mass of 1.0 g.” number H Relative atomic 1.0 mass, Ar “The atomic mass of Carbon is 12 gmol-1.” Thursday, 16 September 2010
  132. 132. Mr = Relative molecular mass = the number of grams per mole for the compound. A formula gives us the mole ratio of each type of atom in a compound. Molecular masses can be calculated from relative atomic mass values and formulae. Example The formula for Methane is CH4. This means that in a sample of Methane there are 4 moles of hydrogen atoms for every mole of carbon. Mr(CH4) = the number of grams per mole of methane molecules. The periodic table tells us that: C = 12.0g per mole H = 1.0g per mole So ...... Mr(CH4) = 12.0 + 4 x 1.0 = 16 gmol-1 Thursday, 16 September 2010
  133. 133. Example: A question from the 2003 NCEA examination paper Thursday, 16 September 2010
  134. 134. Example: A question from the 2003 NCEA examination paper Mr(FeCO3) = 55.9 + 12 + (3 x 16) = 115.9 gmol-1 Thursday, 16 September 2010
  135. 135. Example: A question from the 2003 NCEA examination paper Mr(FeCO3) = 55.9 + 12 + (3 x 16) = 115.9 gmol-1 Mr[Fe(NO3)3] = 55.9 + (3 x 14) + (9 x 16) = 241.9 gmol-1 Thursday, 16 September 2010
  136. 136. Example: A question from the 2003 NCEA examination paper Mr(FeCO3) = 55.9 + 12 + (3 x 16) = 115.9 gmol-1 Mr[Fe(NO3)3] = 55.9 + (3 x 14) + (9 x 16) = 241.9 gmol-1 Mr(Fe2O3) = 2 x 55.9 + 3 x 16 = 159.8 gmol-1 Thursday, 16 September 2010
  137. 137. A question from the 2005 NCEA examination paper “Try these questions out for yourself” ESA: Ex 12A Thursday, 16 September 2010
  138. 138. A question from the 2005 NCEA examination paper “Try these questions out for yourself” 159.6 gmol-1 ESA: Ex 12A Thursday, 16 September 2010
  139. 139. A question from the 2005 NCEA examination paper “Try these questions out for yourself” 159.6 gmol-1 106 gmol-1 ESA: Ex 12A Thursday, 16 September 2010
  140. 140. A question from the 2005 NCEA examination paper “Try these questions out for yourself” 159.6 gmol-1 106 gmol-1 261 gmol-1 ESA: Ex 12A Thursday, 16 September 2010
  141. 141. PERCENTAGE COMPOSITION Percentage composition of an element/s in a compound is the ratio of the mass per mole of the element/s to the mass per mole of the compound expressed as a percentage. Example Consider that you need to calculate the percentage of Sulfur in Copper Sulphate. The relative atomic masses are: Cu = 63.5 gmol-1 S = 32.1 gmol-1 O = 16.0 gmol-1 Mr (CuSO4) = 159.6 gmol-1 (from previous question) Ar (S) = 32.1 gmol-1 Percentage Sulfur = 32.1 = 20.1% 159.6 Thursday, 16 September 2010

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