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Other chemical fuels

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The document discusses the chemical alkynes, specifically ethyne (C2H2). It describes the laboratory preparation of ethyne from calcium dicarbide and water, which produces ethyne gas. Ethyne is colorless, insoluble in water but soluble in nonpolar solvents, and burns with a very hot, smoky flame when combusted. It can be used to cut and weld steel in oxy-acetylene torches. The document also discusses the manufacture and uses of hydrogen, including from natural gas reforming and electrolysis of water, and its use in the Haber process and as a fuel. Fuel cells that use hydrogen are also mentioned.

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Other Chemical Fuels
Alkynes  General formula CnH2n-2  First member ethyne  Functional group -C≡C- C2H2
Laboratory Preparation of ethyne CaC2(s) + 2 H2O(l) = Ca(OH)2(s) + C2H2(g)
Laboratory Preparation of ethyne  Calcium dicarbide [CaC2] is a grey lumpy solid.  Reacts very exothermically with water [Fizzing and steam produced as it reacts] Calcium hydroxide is a white powder with a greater volume Acidified Copper Sulphate solution removes impurities such as phosphine gas - produced when calcium phosphide impurity reacts with water.   
Physical Properties  Ethyne is a colourless gas with a sickly sweet smell.  It is insoluble in water but soluble in non polar solvents like cyclohexane.
Combustion  Ethyne burns in oxygen with a very smoky yellow flame  In excess pure oxygen it burns with a very hot flame [3150oC] 1299 kJ mol-1  This is used to cut and weld steel.  Old name for ethyne is acetylene hence oxyacetylene torch or burner
Tests for Unsaturation  Ethyne  Ethyne decolourises bromine water. decolourises acidified potassium manganate(VII) (potassium permanganate.
Uses of Ethyne  Ethyne is used in the oxy-acetylene torch to cut and weld steel
Manufacture of Hydrogen  Steam Reforming of Natural Gas CH4 + H2O = 3 H2 + CO  In presence of a suitable catalyst
Manufacture of Hydrogen  Electrolysis of Water  using dilute H2SO4  forms at cathode [negative electrode]  Overall  Too H2O = H2 + 1/2 O2 expensive in most parts of world
Uses of Hydrogen  Haber Process for producing ammonia N2 + 3 H2 = 2 NH3  Hydrogenating vegetable oils
Uses of Hydrogen  Fuel - about 10% of worlds production of hydrogen is used as fuel  Environmentally friendly  Water is the only product of combustion  H2 + 1/2 O2 = H2O  It is explosive with air  Difficulties with storage and transport
Fuel Cell

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  • 3. Laboratory Preparation of ethyne CaC2(s) + 2 H2O(l) = Ca(OH)2(s) + C2H2(g)
  • 4. Laboratory Preparation of ethyne  Calcium dicarbide [CaC2] is a grey lumpy solid.  Reacts very exothermically with water [Fizzing and steam produced as it reacts] Calcium hydroxide is a white powder with a greater volume Acidified Copper Sulphate solution removes impurities such as phosphine gas - produced when calcium phosphide impurity reacts with water.   
  • 5. Physical Properties  Ethyne is a colourless gas with a sickly sweet smell.  It is insoluble in water but soluble in non polar solvents like cyclohexane.
  • 6. Combustion  Ethyne burns in oxygen with a very smoky yellow flame  In excess pure oxygen it burns with a very hot flame [3150oC] 1299 kJ mol-1  This is used to cut and weld steel.  Old name for ethyne is acetylene hence oxyacetylene torch or burner
  • 7. Tests for Unsaturation  Ethyne  Ethyne decolourises bromine water. decolourises acidified potassium manganate(VII) (potassium permanganate.
  • 8. Uses of Ethyne  Ethyne is used in the oxy-acetylene torch to cut and weld steel
  • 9. Manufacture of Hydrogen  Steam Reforming of Natural Gas CH4 + H2O = 3 H2 + CO  In presence of a suitable catalyst
  • 10. Manufacture of Hydrogen  Electrolysis of Water  using dilute H2SO4  forms at cathode [negative electrode]  Overall  Too H2O = H2 + 1/2 O2 expensive in most parts of world
  • 11. Uses of Hydrogen  Haber Process for producing ammonia N2 + 3 H2 = 2 NH3  Hydrogenating vegetable oils
  • 12. Uses of Hydrogen  Fuel - about 10% of worlds production of hydrogen is used as fuel  Environmentally friendly  Water is the only product of combustion  H2 + 1/2 O2 = H2O  It is explosive with air  Difficulties with storage and transport