Oxygen

 

Oxygen

Chemical formula	O
Atomic Number	8
OTP appearance	colorless gas
Molar Mass(g/mol)	16
Density(g/cc)	0.0014
Melting Point(°C)	-218.8
Boiling Point(°C)	-219
Speed of sound 20°C, 1atm (m/s)	326
NFPA 704	0 3 2 ox

Under normal circumstances is a gas (O₂). It is a primary constituent of air. All normal forms of fire convert oxygen and a fuel into carbon dioxide.

Uses

Primary

• Respiration
• Chemical oxidation

Natural occurrence

• Elemental oxygen does occur naturally in air. At 20°C 1L of (dry) air contains .0079 mol of O₂

Hazards

• Fire
• Most life will die in a pure oxygen environment

Production

Extraction

• from air. See air for separation of the gases in air.

Chemical

• Heat mercuric oxide, potassium permanganate, or sodium dichromate

  2 HgO

  {

  →

  500°C}

  2 Hg + O₂

  2 KMnO₄

  {

  →

  240°C}

  K₂MnO₄ + MnO₂ + O₂

• Heating barium peroxide can store and release oxygen
• Hydrogen peroxide can be catalytically reduced (by manganese dioxide or silver) to water and oxygen

  2 H₂O₂

  {MnO₂

  →

  }

  2 H₂O + O₂

Electrolytic

• Electrolysis of water produces oxygen at the anode and hydrogen at the cathode

  2 H₂O(l) - 4e^- → O₂(g) + 4 H⁺(aq)

  4H⁺(aq) + 4eⁱ(aq) → H₂(g)

Disposal

Oxygen can be released directly into the environment

See Also

• nitrogen and carbon dioxide, the other major gasseous constituents of air