What are sulfur oxides?

Sulfur oxides (SOx) are compounds of sulfur and oxygen molecules. Sulfur dioxide (SO2) is the predominant form found in the lower atmosphere. Sulfur oxide is the common term for many types of sulfur and oxygen containing compounds such as:

• Lower sulfur oxides(S_nO, S₇O₂ and S₆O₂)
• Sulfur monoxide(SO)
• Sulfur dioxide(SO₂)
• Sulfur trioxide(SO₃)
• Higher sulfur oxides(SO₃ and SO₄ and polymeric condensates of them)
• Disulfur monoxide(S₂O)
• Disulfur dioxide(S₂O₂)

These molecules are colorless, but have a very distinct and strong scent and taste that can be detected when the gas is of high concentration.

Sulfur monoxide, SO, is a common sulfur oxide compound that is rarely found outside of space. When concentrated or condensed it becomes S2O2, or disulfur dioxide (see below). Under extreme laboratory conditions sulfur monoxide can be produced by treating sulfur dioxide with sulfur vapors in a glow discharge. In spaced sulfur monoxide is detected around one of Jupiter’s moons, Lo, in the atmosphere and in the plasma torus. It has also been found in the atmospheres of Venus and the Hale-Bopp comet as well as the interstellar medium. In biological chemistry, sulfur monoxide may have some biological activity, the formation of transient SO in porcine coronary artery has been inferred from the reaction products. Because it is rare in occurrence it is difficult to fully understand the hazardous of sulfur monoxide but as sulfur dioxide it is both toxic and corrosive.

Sulfur dioxide, one of the more popular sulfur oxides, is a poisonous gas with a smell that is often described as a just struck match. Sulfur dioxide can be can be liquefied at room temperatures under moderate pressures. As a liquid it freezes at -37° C (-99.4° F) and boils at -10° C (+14° F) under atmospheric pressure. Sulfur dioxide, like sulfur monoxide is often found in space. In the atmosphere of Venus it is the third-most significant gas at 140 ppm. Interestingly, on Venus it is a contributor to global warming and is a key component of the chemical reactions in the planets atmosphere. [Read more…]