Information AboutSulfate |
| CATEGORIES ABOUT SULFATE | |
| sulfates | |
| oxoanions | |
| particulates | |
| climate forcing agents | |
| climate change | |
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In Inorganic Chemistry , a sulfate ( IUPAC -recommended spelling; also '''sulphate''' in British English ) is a Salt of Sulfuric Acid . CHEMICAL PROPERTIES The sulfate ion is a Polyatomic Anion with the Empirical Formula S O 42− and a molecular mass of 96.06 Daltons ; it consists of one central sulfur Atom surrounded by four equivalent oxygen atoms in a Tetrahedral arrangement. The sulfate ion carries a negative two Charge and is the Conjugate Base of the '''hydrogen sulfate''' (also known as '''bisulfate''') ion, HSO4−, which is the conjugate base of H2SO4, sulfuric acid. Sulfate compounds arise when to a solution containing sulfate ions. The appearance of a white precipitate, which is Barium Sulfate , indicates that sulfate anions are present. USES Sulfates are important in both the chemical industry and biological systems:
Sulfur oxoanions
ENVIRONMENTAL EFFECTS Sulfates occur as microscopic particles ( Aerosols ) resulting from Fossil Fuel and Biomass combustion. They increase the acidity of the Atmosphere and form Acid Rain . Main effects on climate The first (direct) effect is to scatter light, effectively increasing the Earth's Albedo . This effect is moderately well understood and leads to a cooling from the negative Radiative Forcing of about 0.5 W/m2 relative to pre-industrial values, Figure 3: The global mean radiative forcing of the climate system for the year 2000, relative to 1750 . Climate Change 2001: Working Group I: The Scientific Basis. IPCC . partially offsetting the larger (about 2.4 W/m2) warming effect of Greenhouse Gas es. The effect is strongly spatially non-uniform, being largest downstream of large industrial areas. The first indirect effect is also known as the Twomey Effect . Sulfate aerosols can act as Cloud Condensation Nuclei and this leads to greater numbers of smaller droplets of water. Lots of smaller droplets can diffuse light more efficiently than just a few larger droplets. The second indirect effect is the further knock-on effects of having more cloud condensation nuclei. It is proposed that these include the suppression of drizzle, increased cloud height (Pincus & Baker 1994), to facilitate Cloud formation at low Humidities and longer cloud lifetime (Albrecht 1989). Sulfate may also result in changes in the particle size distribution, which can affect the clouds radiative properties in ways that are not fully understood. Chemical effects such as the dissolution of soluble gases and slightly soluble substances, surface tension depression by organic substances and accommodation coefficient changes are also included in the second indirect effect Chemical Amplification (or dampening) of the Twomey Effect: Conditions derived from droplet activation theory . T.A. Rissman, A. Nenes, J.H. Seinfeld.. The indirect effects probably have a cooling effect, perhaps up to 2 W/m2, although the uncertainty is very large. Sulfates are therefore implicated in Global Dimming , which may have acted to offset some of the effects of Global Warming . SEE ALSO REFERENCES |
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