Ethane (thing)

      H      H   H      rotation \    H         H
      |       \ /       ==========    |         |
      C--------C        \             C---------C
     / \       |                     / \       / \
    H   H      H                    H   H     H   H

It is hard to show the real angles that exist in the ethane molecule as the hydrogen atoms on each carbon are pointing out somewhat at each end. In any case, one of the most interesting things about the ethane molecule is that the carbon-carbon bond will rotate so the hydrogen atoms can line up or not. This is in contrast with ethene C₂H₄ and ethyne (acetylene) C₂H₂ since the double and triple covalent bonds do not rotate.

Basic Data:

• Melting point: -183.3º C
• Boiling point: -88.6º C
• pK_a: 50
• density: 0.572 at -100º C relative to water at 4º C.
• Molecular weight: 30.07
• Combustion of ethane with oxygen: 2 C₂H₆ + 7 O₂ -> 4 CO₂ + 6 H₂O which creates ΔHº = 1559.9 kJ/kmol of ethane of energy.
• Heat of formation: ΔHº_f = -84.67 kJ/kmol.

Ethane is the base for ethanol or common alcohol, vinegar (acetic acid) and a number of refrigerants when combined with halogens.

---

Sources:

Chemistry: Experiment and Theory by Bernice Segal

Handbook of Chemistry and Physics, 74th Edition, David Lide, editor-in-chief.