Copper(II) nitrate is an inorganic salt with the formula Cu(NO3)2. It is commonly called cupric nitrate and contains copper in the +2 oxidation state and nitrate anions. For general reference it is described as a water-soluble copper(II) salt and can be found in several hydrated and anhydrous forms; see a concise compound summary for basic data.

Characteristics

Copper(II) nitrate typically appears as blue to blue-green crystalline solids, most commonly encountered as the trihydrate. It dissolves readily in water, producing blue solutions characteristic of divalent copper. In its coordination chemistry the Cu2+ center usually occupies octahedral sites bound to oxygen donors. The d9 electronic configuration of Cu2+ makes many of its salts paramagnetic and colored due to d–d electronic transitions. As a nitrate salt it behaves as an oxidizer under some conditions and decomposes on heating to copper(II) oxide and nitrogen oxides.

Preparation and reactions

In the laboratory copper(II) nitrate is prepared by treating copper metal, copper oxide, or carbonate with nitric acid; the reaction with concentrated acid typically evolves brown nitrogen dioxide gas. Like other copper(II) salts, it forms characteristic deep-blue complex ions with ammonia and can act as a soluble source of Cu2+ for precipitation, redox, or coordination reactions. Thermal decomposition yields copper oxides, and contact with reducing organic materials can be hazardous because of the oxidizing nitrate.

Uses and examples

  • Common reagent in research and teaching for providing soluble Cu2+.
  • Precursor to copper oxide catalysts and materials used in ceramics and electronics.
  • Mordant in some dyeing or leather treatments and occasional use in etching or patination of copper surfaces.
  • Occasional role in pyrotechnics to introduce blue/green hues, though its oxidizing properties and toxic decomposition products limit its desirability.

Safety and environmental notes

Copper(II) nitrate is toxic to aquatic life and can be harmful if ingested or inhaled; it is an oxidizer and can intensify fires. Good laboratory practice includes wearing appropriate personal protective equipment, working in a fume hood when acids or NOx gases may form, and preventing release to drains. For handling guidance and regulatory data consult a material safety data source or safety information.

Distinct from copper(I) salts, which are much less stable in air, copper(II) nitrate is the common, stable nitrate of the Cu2+ ion and is one of several soluble copper(II) salts (others include sulfate and chloride) used interchangeably in many chemical processes. For more detailed studies of structure or reactivity, see specialized references or chemical databases on oxidation states.