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Copper(II) sulfate

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Copper(II) sulfate
Crystal of copper(II)sulfate4 · 5H2O
Crystal of copper(II)sulfate4 · 5H2O
Photo of powdered copper(II) sulphate pentahydrate
Photo of powdered copper(II) sulphate pentahydrate
Ball-and-stick model of the unit cell of anhydrous copper(II) sulfate
Ball-and-stick model of the unit cell of anhydrous copper(II) sulfate
Space-filling model of part of the crystal structure of anhydrous copper(II) sulfate
Space-filling model of part of the crystal structure of anhydrous copper(II) sulfate
Names
IUPAC name
Copper(II) sulfate
Other names
Cupric sulfate
Cupper(II)sulphate
Blue vitriol
Bluestone
Chalcanthite
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.028.952 Edit this at Wikidata
EC Number
  • 231-847-6
RTECS number
  • GL8800000 (anhydrous)
    GL8900000 (pentahydrate)
  • InChI=1/Cu.H2O4S/c;1-5(2,3)4/h;(H2,1,2,3,4)/q+2;/p-2
    Key: ARUVKPQLZAKDPS-NUQVWONBAI
  • [Cu+2].[O-]S([O-])(=O)=O
Properties
CuSO4
Molar mass 159.61 g/mol (anhydrous)
249.68 g/mol (pentahydrate)
Appearance blue crystalline solid (pentahydrate)
gray-white powder (anhydrous)
Density 3.603 g/cm3 (anhydrous)
2.284 g/cm3 (pentahydrate)
Melting point 110 °C (−4H2O)
150 °C (423 K) (−5H2O)
< 650 °C decomp.
pentahydrate
31.6 g/100 ml (0 °C)
203.3 g/100 ml (100 °C)
form unspecified
32 g/100 mL (20°C)
61.8 g/100 mL (60°C)
114 g/100 mL (100°C)
Solubility anhydrous
insoluble in ethanol
pentahydrate
soluble in methanol and ethanol
1.514 (pentahydrate)
Structure
Triclinic
Octahedral
Thermochemistry
109.05 J K−1 mol−1
Hazards
NFPA 704 (fire diamond)
NFPA 704 four-colored diamondHealth 2: Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. E.g. chloroformFlammability 0: Will not burn. E.g. waterInstability 1: Normally stable, but can become unstable at elevated temperatures and pressures. E.g. calciumSpecial hazards (white): no code
2
0
1
Flash point Non-inflammable
Lethal dose or concentration (LD, LC):
300 mg/kg
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 (CuSO4·5H2O), 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

Preparation of copper(II) sulfate by electrolyzing sulfuric acid, using copper electrodes

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. It can also be prepared by electrolysis of magnesium sulfate [Epsom salts] solution at moderate voltage with a copper anode: this reaction produces hydrogen, copper sulfate solution, and magnesium hydroxide precipitate:

MgSO4(aq) + 2 H2O + Cu(s) → H2(g) + Mg(OH)2(s) + CuSO4(aq)


Chemical properties

Copper(II) sulfate pentahydrate decomposes before melting, losing two water molecules at 63°C, followed by two more at 109°C and the final water molecule at 220°C.[citation needed] 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 a herbicide, fungicide and 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 a herbicide is not agricultural, but instead for control of invasive aquatic plants and the roots of plants near pipes containing water. It is used in swimming pools as an algaecide. A dilute solution of copper sulfate is used to treat aquarium fish for parasitic infections,[4] and is also used to remove snails from aquariums. Copper ions are highly toxic to 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 Escherichia 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 less rapidly.[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 transacetylation 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, producing iron(II) sulfate, and copper precipitates.

Fe + CuSO4 → FeSO4 + Cu

Other uses

Lowering a zinc etching plate into the copper sulfate solution.

Medical

Copper sulfate was also used in the past as an emetic.[10] It is now considered too toxic for this use.[11] It is still listed as an antidote in the World Health Organization's ATC code V03.[12]

Art

In 2008, the artist Roger Hiorns filled an abandoned waterproofed council flat in London with 75,000 liters of copper sulfate solution. The solution was left to crystallise for several weeks before the flat was drained, leaving crystal-covered walls, floors and ceilings.

The work is titled Seizure.[13]

Etching

Copper sulfate is also used to etch zinc plates for intaglio printmaking.[14][15]

Toxicological Effects

Copper sulfate is a strong irritant [16]. The usual routes by which humans can receive toxic exposure to copper sulfate are through eye or skin contact, as well as by inhaling powders and dusts [17]. Skin contact may result in itching or eczema [18]. Eye contact with copper sulfate can cause conjunctivitis, inflammation of the eyelid lining, ulceration, and clouding of the cornea [19] Upon acute oral exposure, copper sulfate turns to be only moderately toxic [20]. According to studies, the lowest dose of copper sulfate that had a toxic impact on humans is 11 mg/kg.[21]. Because of its irritating effect on the gastrointestinal tract, vomiting is automatically triggered in case of the ingestion of copper sulfate. However, if copper sulfate is retained in the stomach, the symptoms can be severe. After 1-12 grams of copper sulfate are swallowed, such poisoning signs may occur as a metallic taste in the mouth, burning pain in the chest, nausea, diarrhea, vomiting, headache, discontinued urination, which leads to yellowing of the skin. In case of copper sulfate poisoning, injury to the brain, stomach, liver, kidneys may also occur [19]

References

  1. ^ "Copper(II) sulfate MSDS". Oxford University. Retrieved 2007-12-31.
  2. ^ Holleman, A. F.; Wiberg, E. Inorganic Chemistry. San Diego&year= 2001&isbn= 0-12-352651-5: Academic Press.{{cite book}}: CS1 maint: location (link) CS1 maint: multiple names: authors list (link)
  3. ^ "Uses of Copper Compounds: Copper Sulfate's Role in Agriculture". Copper.org. Retrieved 2007-12-31.
  4. ^ "All About Copper Sulfate". National Fish Pharmaceuticals. Retrieved 2007-12-31.
  5. ^ 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)
  6. ^ Hoffman, R. V. (2001). Copper(II) Sulfate, in Encyclopedia of Reagents for Organic Synthesis. John Wiley & Sons. doi:10.1002/047084289X.rc247.
  7. ^ 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.
  8. ^ 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.
  9. ^ "Process for the preparation of stable copper (II) sulfate monohydrate applicable as trace element additive in animal fodders". Retrieved 2009-07-07.
  10. ^ Holtzmann NA, Haslam RH (1968). "Elevation of serum copper following copper sulfate as an emetic". Pediatrics. 42 (1): 189–93. PMID 4385403. {{cite journal}}: Unknown parameter |month= ignored (help)
  11. ^ Olson, Kent C. (2004). Poisoning & drug overdose. New York: Lange Medical Mooks/McGraw-Hill. p. 175. ISBN 0-8385-8172-2.
  12. ^ V03AB20 (WHO)
  13. ^ "Seizure homepage". Artangel.org.uk. Retrieved 2009-09-21.
  14. ^ Bordeau etch
  15. ^ The Chemistry of using Copper Sulfate Mordant
  16. ^ Windholz, M., ed. 1983. The Merck Index. Tenth edition. Rahway, NJ: Merck and Company.
  17. ^ U. S. Environmental Protection Agency. 1986 Guidance for reregistration of pesticide products containing copper sulfate. Fact sheet no 100. Office of Pesticide Programs. Washington, DC.
  18. ^ TOXNET. 1975-1986. National library of medicine's toxicology data network. Hazardous Substances Data Bank (HSDB). Public Health Service. National Institute of Health, U. S. Department of Health and Human Services. Bethesda, MD: NLM.
  19. ^ a b Clayton, G. D. and F. E. Clayton, eds. 1981. Patty's industrial hygiene and toxicology. Third edition. Vol. 2: Toxicology. NY: John Wiley and Sons.
  20. ^ 1986. Guidance for reregistration of pesticide products containing copper sulfate. Fact sheet no 100. Office of Pesticide Programs. Washington, DC.
  21. ^ National Institute for Occupational Safety and Health (NIOSH). 1981- 1986. Registry of toxic effects of chemical substances (RTECS). Cincinnati, OH: NIOSH.
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