Copper(II) sulfate: Difference between revisions
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==Chemical properties== |
==Chemical properties== |
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Copper(II) sulfate pentahydrate [[chemical decomposition|decomposes]] before melting, losing four water molecules at 110 °C and all five at 150 °C. At 650 °C, copper(II) sulfate decomposes into copper(II) oxide (CuO) and [[sulfur trioxide]] (SO<sub>3</sub>). Its blue color is due to water of hydration. When heated in an open flame the crystals are dehydrated and turn grayish-white. |
Copper(II) sulfate pentahydrate [[chemical decomposition|decomposes]] before melting, losing four water molecules at 110 °C and all five at 150 °C. At 650 °C, copper(II) sulfate decomposes into copper(II) oxide (CuO) and [[sulfur trioxide]] (SO<sub>3</sub>). Its blue color is due to water of hydration. When heated in an open flame the crystals are dehydrated and turn grayish-white. <ref>Holleman, A. F.; Wiberg, E. ''Inorganic Chemistry'' Academic Press: San Diego, 2001. ISBN 0-12-352651-5.</ref> |
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==Uses== |
==Uses== |
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Revision as of 15:48, 27 February 2009
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| Names | |||
|---|---|---|---|
| IUPAC name
Copper(II) sulfate
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| Other names | |||
| Identifiers | |||
| ECHA InfoCard | 100.028.952 | ||
| EC Number |
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| RTECS number |
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CompTox Dashboard (EPA)
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| Properties | |||
| CuSO4 | |||
| Molar mass | 159.61 g/mol (anhydrous) 249.68 g/mol (pentahydrate) | ||
| Appearance | blue crystalline solid (pentahydrate) gray-white powder (anhydrous) | ||
| Melting point | 110 °C (−4H2O) 150 °C (423 K) (−5H2O) < 650 °C decomp. | ||
| 31.6 g/100 ml (0 °C) | |||
| Structure | |||
| Triclinic | |||
| Octahedral | |||
| Thermochemistry | |||
Std molar
entropy (S⦵298) |
109.05 J K−1 mol−1 | ||
| Hazards | |||
| Flash point | Non-flammable | ||
| Related compounds | |||
Other cations
|
Nickel(II) sulfate Zinc sulfate | ||
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Copper(II) sulfate is the chemical compound with the formula CuSO4. This salt exists as a series of compounds that differ in their degree of hydration. The anhydrous form is a pale green or gray-white powder, whereas the pentahydrate, the most commonly encountered salt, is bright blue. The anhydrous form occurs as a rare mineral known as chalcocyanite. The hydrated copper sulfate occurs in nature as chalcanthite (pentahydrate), and two more rare ones: bonattite (trihydrate) and boothite (heptahydrate). Archaic names for copper(II) sulfate are "blue vitriol" and "bluestone".[1]
Preparation
Since it is available commercially, copper sulfate is usually purchased and not prepared in the laboratory. It can be made by the action of sulfuric acid on a variety of copper(II) compounds, for example copper(II) oxide; this oxide can be generated with the addition of hydrogen peroxide to the acid. It may also be prepared by electrolyzing sulfuric acid, using copper electrodes.
Chemical properties
Copper(II) sulfate pentahydrate decomposes before melting, losing four water molecules at 110 °C and all five at 150 °C. At 650 °C, copper(II) sulfate decomposes into copper(II) oxide (CuO) and sulfur trioxide (SO3). Its blue color is due to water of hydration. When heated in an open flame the crystals are dehydrated and turn grayish-white. [2]
Uses
As an herbicide, fungicide, pesticide
Copper sulfate pentahydrate is a fungicide. Mixed with lime it is called Bordeaux mixture and used to control fungus on grapes, melons, and other berries[3]. Another application is Cheshunt compound, a mixture of copper sulfate and ammonium carbonate used in horticulture to prevent damping off in seedlings. Its use as an herbicide is not agricultural, but instead for control of invasive exotic aquatic plants and the roots of other invasive plants near various pipes that contain water. A dilute solution of copper sulfate is used to treat aquarium fish for various parasitic infections,[4] and is also used to remove snails from aquariums. However, as the copper ions are also highly toxic to the fish, care must be taken with the dosage. Most species of algae can be controlled with very low concentrations of copper sulfate. Copper sulfate inhibits growth of bacteria such as E. coli.
Analytical reagent
Several chemical tests utilize copper sulfate. It is used in Fehling's solution and Benedict's solution to test for reducing sugars, which reduce the soluble blue copper(II) sulfate to insoluble red copper(I) oxide. Copper(II) sulfate is also used in the Biuret reagent to test for proteins.
Copper sulfate is also used to test blood for anemia. The blood is tested by dropping it into a solution of copper sulfate of known specific gravity — blood which contains sufficient hemoglobin sinks rapidly due to its density, whereas blood which does not, floats or sinks slowly.[5]
In a flame test, its copper ions emit a deep blue-green light, much more blue than the flame test for barium.
Organic synthesis
Copper sulfate is employed in organic synthesis.[6] The anhydrous salt catalyses the transacetalization in organic synthesis.[7] The hydrated salt reacts with potassium permanganate to give an oxidant for the conversion of primary alcohols.[8]
Chemistry education
Copper sulfate is a commonly included chemical in children's chemistry sets and is often used to grow crystals in schools and in copper plating experiments. Due to its toxicity, it is not recommended for small children. Copper sulfate is often used to demonstrate an exothermic reaction, in which steel wool or magnesium ribbon is placed in an aqueous solution of CuSO4. It is used in school chemistry courses to demonstrate the principle of mineral hydration. The pentahydrate form, which is blue, is heated, turning the copper sulfate into the anhydrous form which is white, while the water that was present in the pentahydrate form evaporates. When water is then added to the anhydrous compound, it turns back into the pentahydrate form, regaining its blue color, and is known as blue copperas.[9]
In an illustration of a "single metal replacement reaction," iron is submerged in a solution of copper sulfate. Upon standing, iron dissolves and copper precipitates.
- Fe + CuSO4 → FeSO4 + Cu
The copper can also be electroplated to the iron.
Other uses
Other applications include hair dyes, coloring glass, processing of leather and textiles and in pyrotechnics as a green colorant. It is used by some organic cattle farmers in solution as a footbath as a way of increasing the hardness of hoof, thereby reducing incidence of lameness.[10] It also can change the color of a flame if added to it in its dry state, making it green.[11]Copper(II) Sulfate is also used by stained glass artists as a patina, and is painted over solder lines in the stained glass piece in order to protect the lead solder from oxidizing, and also to change the silver solder lines to a bright copper color.
References
- ^ "Copper(II) sulfate MSDS". Oxford University. Retrieved 2007-12-31.
- ^ Holleman, A. F.; Wiberg, E. Inorganic Chemistry Academic Press: San Diego, 2001. ISBN 0-12-352651-5.
- ^ "Uses of Copper Compounds: Copper Sulfate's Role in Agriculture". Copper.org. Retrieved 2007-12-31.
- ^ "All About Copper Sulfate". National Fish Pharmaceuticals. Retrieved 2007-12-31.
- ^ Barbara H. Estridge, Anna P. Reynolds, Norma J. Walters (2000). Basic Medical Laboratory Techniques. Thomson Delmar Learning. p. 166. ISBN 0766812065.
{{cite book}}: CS1 maint: multiple names: authors list (link) - ^ Hoffman, R. V. "Copper(II) Sulfate" Encyclopedia of Reagents for Organic Synthesis, 2001 John Wiley & Sons. DOI: 10.1002/047084289X.rc247
- ^ Hulce, M. Mallomo, J. P.; Frye, L. L.; Kogan, T. P.; Posner, G. H. (1990). "(S)-( + )-2-(p-Toluenesulfinyl)-2-Cyclopentanone: Precursor for Enantioselective Synthesis of 3-Substituted Cyclopentanones". Organic Syntheses
{{cite journal}}: CS1 maint: multiple names: authors list (link); Collected Volumes, vol. 7, p. 495. - ^ Jefford, C. W.; Li, Y.; Wang, Y. "A Selective, Heterogeneous Oxidation using a Mixture of Potassium Permanganate and Cupric Sulfate: (3aS,7aR)-Hexahydro-(3S,6R)-Dimethyl-2(3H)-Benzofuranone". Organic Syntheses
{{cite journal}}: CS1 maint: multiple names: authors list (link); Collected Volumes, vol. 9, p. 462. - ^ http://66.102.9.104/search?q=cache:Jj02FqBkPCAJ:www.freepatentsonline.com/4315915.html+Blue+copperas&hl=en&ct=clnk&cd=3&gl=uk
- ^ "Animal Health and Welfare in Organic Farming: Cattle Diseases: Lameness". Organic Livestock Research Group, VEERU, The University of Reading. Retrieved 2008-08-28.
- ^ "Uses of Copper Compounds: Table A - Uses of Copper Sulfate". Copper.org. Retrieved 2007-12-31.