Copper(II) sulfate

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Copper(II) sulfate
Image:CuSO4 5H2O.jpg
General
Systematic name	Copper(II) sulfate pentahydrate
Other names	Cupper(II) sulfate Cupric sulfate Blue vitriol Bluestone Chalcanthite
Molecular formula	CuSO₄·5H₂O
Molar mass	249.7 g/mol (pentahydrate) 159.6 g/mol (anhydrous)
Appearance	blue crystalline solid (pentahydrate) gray-white powder (anhydrous)
CAS number	[7758-99-8]
EINECS number	231-847-6
Properties
Density and phase	2.284 g/cm³, solid
Solubility in water	31.6 g/100 ml (0 °C)
Melting point	110 °C (− 4H₂O) 150 °C (− 5H₂O) 650 °C decomp.
Structure
Coordination geometry	?
Crystal structure	Triclinic
Thermodynamic data
Standard enthalpy of formation Δ_fH°_solid	-769.98 kJ/mol
Standard molar entropy S°_solid	109.05 J.K⁻¹.mol⁻¹
Safety data
EU classification	Harmful Dangerous for the environment
R-Phrases	R22, R36/38, R50/53
S-Phrases	S2, S22, S60, S61
NFPA 704	Image:NFPA 704.svg 0 3 1
PEL-TWA	1 mg/m³ (OSHA)
IDLH (NIOSH)	100 mg/m³
Flash point	non flammable
RTECS number	GL8800000
Supplementary data page
Structure and properties	n, ε_r, etc.
Thermodynamic data	Phase behaviour Solid, liquid, gas
Spectral data	UV, IR, NMR, MS
Related compounds
Other cations	Copper(I) sulfate Nickel(II) sulfate Zinc sulfate
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox disclaimer and references

Copper(II) sulfate, the chemical compound with the formula CuSO₄, is a common salt of copper. Copper sulfate exists as a series of compounds that differ in their degree of hydration. The anhydrous form is a pale green or gray-white powder, while the hydrated form is bright blue. The archaic name for copper(II) sulfate is blue vitriol.

1 Preparation
2 Uses
3 Safety
4 External links

[edit] Preparation

Since it is available commercially, copper sulfate is usually purchased, not prepared in the laboratory. It is made by the action of sulfuric acid on a variety of copper(II) compounds, such copper(II) oxide and copper carbonate. Such reactions are considered acid-base reactions.

Copper sulfate most occurs in nature as the pentahydrate (CuSO₄ · 5H₂O). This mineral is called chalcanthite. Copper(II) sulfate decomposes before melting. The common pentahydrate form dehydrates, losing four water molecules at 98 °C and all five at 120 °C. At 650 °C copper(II) sulfate decomposes into copper(II) oxide (CuO), Sulfur dioxide (SO₂) and oxygen (O₂). When heated in an open flame the crystals are dehydrated and turn grayish-white.

[edit] Uses

Copper(II) sulfate crystals at 100x magnification

It can be used to plate metals with copper, as a fungicide or herbicide, or as a chemical test for water (the anhydrous form will absorb water, turning blue). Mixed with lime it is called Bordeaux mixture. It is also used in Fehling's solution and Benedict's solution to test for reducing sugars, which reduce the blue Cu²⁺_aq ions to red copper(I) oxide. In addition, Copper (II) Sulphate is also used in Biuret solution to test for proteins. If proteins are present, a violet coloration is obtained. Still other uses include hair dyes and the processing of leather and textiles.

Copper sulphate is also used to test blood for anemia. A drop of the patient's blood is dropped into a container of copper sulfate, if it sinks within a certain time, then the patient has sufficient hemoglobin levels and is not anemic. If the blood floats or sinks too slowly, then the patient is iron-deficient and may be anemic.

In a flame test, copper ions emit a deep blue-green light, much more blue than the flame test for barium.

Copper(II) sulphate is a desiccant.

Copper sulphate is a commonly included chemical in children's chemistry sets and is often used in high school crystal growing and copper plating experiments.

A very dilute solution of Copper sulphate is used to treat aquarium fish of various parasitic infections. However, as the copper ions are also highly toxic to the fish, care must be taken with the dosage.

Image:Copper sulfate.jpg