oxygen

Examples of oxygen in the following topics:

• Uses of Oxygen

  • Oxygen is essential for all aerobic organisms; common medical uses include oxygen therapy, hyperbaric medicine, and space suits.
  • Reactive oxygen species, such as superoxide ion (O2−) and hydrogen peroxide (H2O2), are dangerous by-products of oxygen use in organisms.
  • One of the medical uses of oxygen is oxygen therapy.
  • Oxygen tents were once commonly used in oxygen supplementation, but have since been replaced mostly by the use of oxygen masks or nasal cannulas.
  • Sudden cabin pressure loss activates chemical oxygen generators above each seat, causing oxygen masks to drop.

• Properties of Oxygen

  • Oxygen is an important part of the atmosphere and is necessary to sustain terrestrial life.
  • Oxygen is toxic to obligate anaerobic organisms (organisms which need a lack of oxygen for survival), which were the dominant form of early life on Earth, until O2 began to accumulate in the atmosphere.
  • Free oxygen is too chemically reactive to appear on Earth without the photosynthetic action of living organisms, which use the energy of sunlight to produce elemental oxygen from water.
  • Diatomic oxygen gas currently constitutes 20.8 percent of the volume of air.
  • The two oxygen atoms in diatomic oxygen are chemically bonded to each other with a spin triplet electron configuration.

• Oxides

  • Metal oxides typically contain an anion of oxygen in the oxidation state of −2.
  • Two independent pathways for corrosion of elements are hydrolysis and oxidation by oxygen.
  • The combination of water and oxygen is even more corrosive.
  • Virtually all elements burn in an atmosphere of oxygen or an oxygen-rich environment.
  • Cesium is so reactive with oxygen that it is used as a getter in vacuum tubes.

• Silicate Units, Silicate Chains, Silicate Sheets

  • Each oxygen atom forms one vertex of the tetrahedron.
  • The silicon to oxygen atom ratio is 1:4.
  • The silicon to oxygen ratio is 2:7.
  • They consist of single chains (SiO32−)n, in which the silicon to oxygen atom ratio is 1:3, and double chains (Si4O116−)n, in which the silicon to oxygen atom ratio is 4:11.
  • Red balls correspond to oxygen, and gray to silicon atoms.

• Ozone Depletion

  • In the stratosphere, absorption of ultraviolet photons results in the photodissociation (breaking apart) of oxygen molecules.
  • These atomic oxygen (O) radicals react with oxygen gas (O2) to produce ozone (O3); ozone's absorption of ultraviolet light can then cause oxygen gas to re-form.
  • The reaction of these free radicals with ozone disrupts the ozone-oxygen cycle, leading to the destruction of stratospheric ozone and the depletion of the ozone layer.
  • In the simplest example of such a cycle, a chlorine atom reacts with an ozone molecule, taking an oxygen atom (forming ClO, chlorine monoxide) and leaving a normal oxygen molecule (O2).
  • The chlorine monoxide can then react with a second molecule of ozone (O3) to yield another chlorine atom and two molecules of oxygen.

• Ethers

  • An ether group is an oxygen atom connected to two alkyl or aryl groups.
  • The oxygen of the ether is more electronegative than the carbons.
  • For example, diethyl ether is the ether with an ethyl group on each side of the oxygen atom.
  • The "oxa" is an indicator of the replacement of the carbon by an oxygen in the ring.
  • Ethers tend to form peroxides in the presence of oxygen or air.

• Borates: Boron-Oxygen Compounds

  • Larger borates are composed of trigonal planar BO3 or tetrahedral BO4 structural units, joined together via shared oxygen atoms; these may be cyclic or linear in structure.
  • Boron monoxide (B2O) is another chemical compound of boron and oxygen.
  • Boron suboxide (chemical formula B6O) is a solid compound containing six boron atoms and one oxygen atom.

• Mass-to-Mass Conversions

  • This can be illustrated by the following example, which calculates the mass of oxygen needed to burn 54.0 grams of butane (C4H10).
  • The molar amount of O2 can now be easily converted back to grams of oxygen:
  • In summary, it was impossible to directly determine the mass of oxygen that could react with 54.0 grams of butane.
  • But by converting the butane mass to moles (0.929 moles) and using the molar ratio (13 moles oxygen : 2 moles butane), one can find the molar amount of oxygen (6.05 moles) that reacts with 54.0 grams of butane.
  • Using the molar amount of oxygen, it is then possible to find the mass of the oxygen (193 g).

• Polar Ozone Holes

  • Ultraviolet light splits oxygen gas (O2) to form monatomic oxygen (O) that can react with additional oxygen gas molecules to form ozone (O3).
  • The ozone produced can then go on to react with monatomic oxygen and re-form oxygen gas.
  • The chlorine breaks an oxygen off from ozone, producing diatomic oxygen.
  • The resulting ClO can also destroy another ozone molecule to form more diatomic oxygen:

• Electrolysis of Water

  • If the object is to produce hydrogen and oxygen, the added electrolyte must be energetically more difficult to oxidize or reduce than water itself.
  • Hydrogen will appear at the cathode, the negatively charged electrode, where electrons enter the water, and oxygen will appear at the anode, the positively charged electrode.
  • The number of moles of hydrogen generated is twice the number of moles of oxygen, and both are proportional to the total electrical charge conducted by the solution.
  • The number of electrons pushed through the water is twice the number of generated hydrogen molecules, and four times the number of generated oxygen molecules.