Copper(II) sulfate

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Copper(II) sulfate
General
Systematic name	Copper(II) sulfate pentahydrate
Other names	Cupric sulfate Blue vitriol Bluestone Chalcanthite
Molecular formula	CuSO4·5H2O
Molar mass	249.68 g/mol (pentahydrate) 159.58 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 ΔfH°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
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, εr, 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) [Chemical infoboxInfobox disclaimer and references]

Copper(II) sulfate or copper(II) sulphate (CuSO₄) is the most common copper salt, made by the action of sulfuric acid on the base copper(II) oxide. 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 was cupric sulfate. Some common names include blue stone and blue vitriol. Like most other copper compounds, copper(II) sulfate is poisonous to humans.

Copper(II) sulfate is a desiccant. As such, it most commonly occurs in nature as copper(II) sulfate pentahydrate (CuSO₄ · 5H₂O). This mineral is called chalcanthite. Copper(II) sulfate decomposes before melting. The common pentahydrate form dehydrates, 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), Sulfur dioxide (SO₂) and oxygen (O₂).

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, to test for reducing sugars, which reduce the blue Cu²⁺_aq ions to red copper(I) oxide. Still other uses include hair dyes and the processing of leather and textiles.

Copper sulfate 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 haemogloblin 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.

When heated in an open flame the crystals are dehydrated and turn grayish-white.

Copper sulfate is a commonly included chemical in childrens chemistry sets and is often used in high school crystal growing and copper plating experiments.

Large crystals of copper sulfate

External links

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• [International Chemical Safety Card 0751] (anhydrous)
• [International Chemical Safety Card 1416] (pentahydrate)
• [National Pollutant Inventory - Copper and compounds fact sheet]
• [UNCP Copper]

• For a full list of external links to MSDSs, spectroscopic data, commercial chemicals suppliers etc. for this compound, see [Chemical sources].

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