Copper(II) Sulfate

OVERVIEW

Copper(II) sulfate (KOPP-er two SUL-fate) is a white crystalline powder in its anhydrous state, although it occurs most commonly as the pentahydrate, CuSO₄·5H₂O, which is a blue granular crystalline solid. When the pentahydrate is heated, it loses its water of hydration and returns to its white, powdery anhydrous state. The transition between its white anhydrous form and its blue hydrated form is sometimes used in devices and toys that indicate the presence or absence of moisture in the air.

Copper(II) sulfate is probably the most important and most widely used of all copper compounds. It is used in agriculture, the paints and covering industry, in electrical applications, in the production of other chemicals, and in other industrial and commercial applications.

KEY FACTS

OTHER NAMES:

Cupric sulfate; blue vitriol; blue stone; blue copperas

FORMULA:

CuSO₄

ELEMENTS:

Copper, sulfur, oxygen

COMPOUND TYPE:

Inorganic salt

STATE:

Solid

MOLECULAR WEIGHT:

159.61 g/mol

MELTING POINT:

Not applicable; decomposes above 560°C (1,040°F)

BOILING POINT:

Not applicable

SOLUBILITY:

Very soluble in water; moderately soluble in methyl alcohol; slightly soluble in ethyl alcohol

HOW IT IS MADE

Copper(II) sulfate occurs in nature as the mineral calcanthite. Calcanthite is somewhat rare since copper(II) sulfate dissolves readily in water, and therefore the mineral can leach out of rock by groundwater. The compound is made in the laboratory and commercially by treating copper metal or one of the copper oxides (CuO or Cu₂O) with sulfuric acid (H₂SO₄).

COMMON USES AND POTENTIAL HAZARDS

Copper(II) sulfate is used extensively in agriculture as a soil additive, a fumigant for trees, a feed additive to prevent mineral deficiencies, and as a wood preservative. It is a component, along with calcium oxide (CaO; quicklime), of one of the oldest and most popular plant fumigants, a material called Bordeaux mixture. Many of copper(II) sulfate's uses depend on his highly toxic character. It is used to prevent the growth of mold and mildew; to sanitize surfaces in hospitals; to kill algae in swimming pools, reservoirs, and other bodies of water; as an herbicide to kill weeds; and as a germicide, to prevent the growth of unwanted seeds. Although very effective in such applications, copper(II) is often not the first choice because it may have toxic effects on other plants and animals in the environment and on humans.

Some additional uses of copper(II) sulfate include the following:

• As a mordant in the textile industry;
• In the production of blue pigments for paints, varnishes, glazes, dyes, inks, and other coloring materials;
• In electroplating, where it supplies the copper with which other metals are plated;
• In making lithographic prints and engravings;
• In the preservation and tanning of animal hides;
• As a catalyst in the refining of petroleum;
• As a nutritional supplement to treat copper deficiency disorders;
• In the manufacture of fireworks, where it imparts a blue color to the display; and
• In the production of water-resistant adhesives for wood.

Interesting Facts

• Copper(II) sulfate gets the name blue vitriol from the color of the pentahydrate (blue) plus the fact that it is made from sulfuric acid, which is also called oil of vitriol.

Copper(II) sulfate is known to be toxic to humans and other animals if ingested. It may cause burning in the mouth and stomach, nausea, vomiting, abdominal pain, diarrhea, and a metallic taste in the mouth. It can cause gastrointestinal bleeding and, if not eliminated from the body, can result in kidney and liver damage, depression of the nervous system, paralysis, coma, and death from shock or kidney failure. Prolonged exposure to copper(II) sulfate dust can cause discoloration of the skin, damage to the blood and liver, and irritation of the eyes and nose. Copper(II) sulfate poses some risk to the environment, both because of its toxic nature and because it does not break down readily.

Words to Know

ANHYDROUS

Form of a compound that lacks water.

CATALYST

A material that increases the rate of a chemical reaction without undergoing any change in its own chemical structure.

FUMIGANT

A pesticide that is applied as a gas.

MORDANT

A substance used in dyeing and printing that reacts chemically with both a dye and the material being dyed to help hold the dye permanently to the material.

FOR FURTHER INFORMATION

"Cupric Sulfate." New Jersey Department of Health and SeniorServices. http://www.state.nj.us/health/eoh/rtkweb/0549.pdf (accessed on October 5, 2005).

"Cupric Sulfate Anhydrous." J. T. Baker. http://www.jtbaker.com/msds/englishhtml/c5920.htm (accessed on October 5, 2005).

Ware, George W. The Pesticide Book. Batavia, Ill.: Mesiter, 1999.

Young, Jay A. "Copper (II) Sulfate Pentahydrate." Journal of Chemical Education (February 2002): 158.

See AlsoCopper(II) Oxide