II Oxide, CuO

Copper(II) oxide, CuO. Black solid formed by heating Cu(OH)2, Cu(N03)2, etc. Dissolves in acid to Cu(II) salts, decomposes to CU2O at 800 C. Forms cuprates in solid state reactions. A cuprate(III), KCUO2, is also known. 

Ammonia will reduce metallic oxides which are reduced by hydrogen (for example copper(II) oxide, CuO, lead(II) oxide, PbO), being itself oxidised to nitrogen ... 

Copper(ll) acetate is prepared by treatment of copper(II) oxide, CuO, or copper(ll) carbonate, CuCOs, with acetic acid, followed by crystaUization ... 

Copper can form two different oxides copper(II) oxide, CuO, and copper(I) oxide, Cu20. Suppose that you find a bottle labelled copper oxide in the chemistry prep room. 

Copper(I) oxide (KOPP-er one OK-side) is also known as cuprous oxide, red copper oxide, copper protoxide, copper hemi-oxide, and copper suboxide. It is a yellowish, red, or brown crystalline substance, depending on its method of preparation. It does not burn and is stable in dry air. In moist air, it slowly changes to copper(II) oxide (CuO). The compound has been used by humans for thousands of years, first as a pigment in glazes, and later in fungicides, electronic components, and industrial reactions. 

There are two series of copper compounds. Copper(I) compounds are derived from the red copper(I) oxide CU2O and contain the copper(I) ion Cu. These compounds are colourless. Most copper(I) salts are insoluble in water, and their behaviour generally resembles that of the silver(I) compounds. They are readily oxidized to copper(II) compounds, which are derivable from the black copper(II) oxide, CuO. Copper(II) compounds contain the copper(II) ion, Cu. Copper(II) salts are generally blue both in solid, hydrated form and in dilute aqueous solution the colour is characteristic really for the tetraaquocuprate(II) ion [Cu(H20)4f only The limit of visibility of the colour of the tetraaquocuprate(II) complex (i.e. the colour of copper(II) ions in aqueous solutions) is 500 pg in a concentration limit of 1 in 10. Anhydrous copper(II) salts, like anhydrous copper(II) sulphate CUSO4, are white (or slightly yellow). In aqueous solutions the blue tetraaquo complex ion is always present for the sake of simplicity however in this text it will be denoted as the simple copper(II) ion Cu . 

The transition from localized behavior to delocalized behavior is an important one. As an example, nickel oxide (NiO) has about the same color as Ni + complexes in aqueous solution. Cu + complexes in aqueous solution are blue, but teud to be green if the ligands are halide ions or violet if the ligands are ammonia molecules. Copper(II) oxide (CuO), on the other hand, is black. Very likely, the wide absorption in the visible region is from an allowed transition that covers the weak ligand field transitions. It cannot be an LM transition since there is no reason to believe that LM transition are in the visible region just in the case of CuO. 

Plan This is a stoichiometry and gas law problem. To find we first need We write and balance the equation. Next, we convert the given mass (35.5 g) of copper(II) oxide, CuO, to amount (mol) and use the molar ratio to find amount (mol) of H2 needed (stoichiometry portion). Then, we use the ideal gas law to convert moles of H2 to liters (gas law portion). A road map is shown, but you are familiar with all the steps. 

Although most of the aqueous chemistry of copper involves the +2 oxidation state, there are a number of important compounds of coppeifl). When copper is heated in oxygen below 1000°C, it forms the black copper(II) oxide, CuO. But above this temperature, it forms the brick-red copper(I) oxide, CU2O. This oxide is found naturally as the mineral cuprite. 

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