Salt Data: Difference between revisions
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=== Sulphates === | === Sulphates === | ||
Sulfates are compounds with the divalent anion [SO <sub> 4 </ sub>] <sup> 2 - </ sup>. The sulfate anion is formed in nature by the oxidation of sulfur or sulfur compounds, especially the sulphides. In many cases, microorganisms (eg, Thio - or sulfur bacteria) are involved in this process. A large proportion of atmospheric sulfate and their precursors (e.g. sulfur dioxide SO <sub> 2 </ sub>) is anthropogenic and is produced by combustion processes. The relatively large [SO <sub> 4 </ sub>] - complex forms stable pure compounds only with large divalent cations such as barium. The smaller the bound ions are, the more unstable are the sulfates, and the more they are forced to stabilize themselves by addition or incorporation of H <sub> 2 </ sub> O. Therefore, most sulfates, especially the one-and three valent elements contain water or have additional anions such as [OH], [CO <sub> 3 </ sub>] and others The sulphates have a number of common characteristics. All sulfates here considered are colourless. The optical birefringence is usually lower than in the carbonates and nitrates. A very large part of the complex salts is slightly to very soluble in water. | |||
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Revision as of 14:38, 1 June 2011
<bibimport/>
Author:Hans-Jürgen Schwarz
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Abstract[edit]
All necessary data, graphics and images for the identification and characterization of a salt are presented. The structure of the salt systems is subject to the major anions.
The Salts[edit]
Here you will find a general overview of the salts. If you need detail information, please go to the pages of the individual salts. Recent reviews on salt and salt damage can be found at [Leitner.etal:2003]Title: Mauersalze und Architekturoberflächen
and [Steiger.etal:2007]Title: Special issue on salt decay
Carbonates[edit]
The carbonates are salts of the "carbonic acid"(H 2 CO 3 ). The main structural element is the planar complex anion [CO 3 ] 2 - . The carbonates have a number of characteristics that distinguish them well from other minerals / salts. The most important characteristic is that they all decompose more or less easily under CO 2 when treated with acids. The alkali and alkali earth carbonate salts are colourless. Most of the other carbonates are usually coloured pale, only the heavy metal carbonates can show strong colours (such as azurite). Noteworthy is the extremely high birefringence of the carbonates, which leads to higher order interference colours. Under thermal treatment the carbonates dissociate mostly at temperatures between 500-900 °C. The solubility in water is relatively good, especially in carbonated water.
to the Carbonates
Nitrates[edit]
Biogenic reactions are a major source of nitrates with the [NO 3] - ion . This usually takes place with the help of bacteria, also nitrogen-containing raw materials such as animal waste, manure and other organic substances may play a role. Nearly all nitrates are soluble in water. The nitrates have remarkable structural similarities with the carbonates; characteristic is the isotypy (same crystal structure) between nitronatrite /calcite and aragonite /niter.
to the Nitrates
Literature[edit]
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