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Alkenes and Alkynes

Introduces unsaturated hydrocarbons, their nomenclature and molecular geometry.

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Fire in the Hole

Fire in the Hole


Credit: Thomas Bresson
Source: http://www.flickr.com/photos/36519414@N00/2954368056
License: CC BY-NC 3.0

For many years, the only light source available for miners and spelunkers were carbide lamps. The lamps were powered by a reaction between calcium carbide (CaC2) and water, producing calcium oxide, heat, and acetylene. The acetylene could then be ignited to provide a warm light for seeing in the otherwise pitch-dark mine.

News You Can Use

  • Acetylene is the simplest alkyne known, consisting of two carbon atoms and two hydrogen atoms. The carbons are attached to one another by a carbon-carbon triple bond. This triple bond makes the acetylene molecule extremely reactive. When ignited in the presence of oxygen, the products are water and carbon dioxide.
  • Approximately 80% of the acetylene produced is used in chemical syntheses. This molecule can react with alcohols and carboxylic acids to produce vinyl monomers which can then be employed for the production of polyvinyl derivatives. Another useful polymer produced from acetylene is neoprene (a synthetic rubber).
  • Credit: jimshooz7
    Source: http://www.flickr.com/photos/jimshooz7/5874594155/
    License: CC BY-NC 3.0

    Neoprene can be used to make rainboots [Figure2]


  • About 20% of acetylene usage is in oxyacetylene torches for welding and cutting. Although arc welding is coming to replace acetylene, there are still applications for acetylene when electricity is not readily available. Oxyacetylene torches are also still widely used for cutting metals.
  • Watch a video at the link below to learn more about the flammability of acetylene. https://www.youtube.com/watch?v=AhpMORUQTr0

Show What You Know

Use the links below to learn more about acetylene, then answer the following questions.

  1. What is one benefit of a carbide lamp as compared to one using incandescent light?
  2. What is a by-product of the carbide reaction?
  3. How is acetylene produced industrially?
  4. Why is acetylene shipped dissolved in acetone or dimethylformaide?
  5. What flame temperature does acetylene produce when mixed with oxygen?

Image Attributions

  1. [1]^ Credit: Thomas Bresson; Source: http://www.flickr.com/photos/36519414@N00/2954368056; License: CC BY-NC 3.0
  2. [2]^ Credit: jimshooz7; Source: http://www.flickr.com/photos/jimshooz7/5874594155/; License: CC BY-NC 3.0

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