Copper

• COPPER (Cu2+/Cu+) is a light-red metal, which is soft, malleable and ductile.
• Copper is largely used in the metallic state.
• It melts at 1038°C. Because of its positive standard electrode potential

  (+0.34 V for the Cu/Cu2+ couple)
• it is soluble in HCl and in dilute sulfuric acid, although in the presence of oxygen some dissolution might take place.
• Medium concentrated nitric acid (8M) dissolves copper readily.
• Hot concentrated sulfuric acid dissolves copper also.
• Copper is also readily dissolve in aqua regia (1:HNO3 & 3:HCl).
• Cu (I) compounds are derived from red copper (I) oxide or Cu2O and contain the Cu (I) ion or Cu+. These compounds are colorless, most of the copper (I) salts are insoluble in water their behavior generally resembling that of the Ag+ compounds. They are readily oxidized to Cu2+ compounds, which are derivable from black copper (II) oxide (CuO).
• Copper (II) salts are generally blue both in solid, hydrated form and in dilute aqueous solution; their color is characteristic really for the tetraquocuprate (II) ion [Cu(H2O)4]2+ only.
• Anhydrous copper (II) salts, like anhydrous Cupric sulfate, are white (or slightly yellow).
• Many of the compounds of copper are green or blue in color and they impart these colors to their solutions (which always have the tetraquo complex ion present).
• The cuprous (Cu+) compounds are unstable and unimportant.
• Copper (II) sulfate, copper (II) chloride and copper (II) nitrate are readily soluble in water. The other important compounds of copper are insoluble or only slightly soluble in water.