II Hydroxide

Vanadium(II) hydroxide is among the most powerful reducing agents known in inorganic chemistry. It is very unstable and extremely sensitive to atmospheric oxidation. In aqueous solution it is oxidized by water, unless some stabilizing substance such as thiocyanate or tellurate(IV) ion is present.  

In this procedure the hydroxide is made from the corresponding sulfate (synthesis 29). 

Thirty milliliters of sodium hydroxide solution (0.02 g./ml.), 10 to 15 ml. of potassium thiocyanate J or potassium tellurate(IV),t and 70 ml. of distilled water are placed in a 500-ml. reaction flask (Fig. 11). The pH of this solution is about 10. The mixture is boiled for 30 minutes with the stopcock open to remove dissolved air. The heating is stopped and the stopcock closed simultaneously. When the temperature drops to 20°, 10 ml. of freshly reduced vanadium(II) sulfate solution, containing about 0.1 g. of vanadium(II), is added directly from the electrolytic cell 

Immediate analysis of a product prepared under similar conditions but with no added thiocyanate or tellurate(IV) ion shows only about 80% vanadium(II), and analysis after 17 hours shows only 62% vanadium (I I). 

The quantity of stabilizing substance may be increased to provide greater protection from atmospheric oxidation. For example, with the use of 30 to 40 ml. of potassium thiocyanate or tellurate(IV) (or a mixture of the two) it is possible to obtain the hydroxide in a form which may be filtered in air and dried for 17 hours on the filter funnel without oxidation. The stabilized hydroxide will return to its original unstable form by treatment with oxidation-accelerating substances such as tetrachloroauric(III) acid [hydrogen tetrachloroaurate(III)], copper(II) sulfate, or palla- 

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If a solution of a tin(II) salt is treated with a small amount of an alkali, tin(II) hydroxide is precipitated, the reaction being represented by the equation ... 

Note that dinitrogen oxide is the other product. In alkaline solution, however, hydroxylamine oxidises iron(II) hydroxide to iron(III) hydroxide and is itself reduced to ammonia. This is an example of the effect of pH change on oxidation-reduction behaviour (p. 101). ... 

Cobaltilll) oxide is obtained as a brown precipitate Co Oj.aq when cobalt(II) hydroxide is oxidised in alkaline conditions (or when a cobalt(III) is decomposed by aqueous alkali). On heating it gives the black mixed oxide C03O4. 

For a cobalt(ll) salt, the precipitation of the blue->pitik cobalt(II) hydroxide by alkali, or precipitation of black cobalt(II) sulphide by hydrogen sulphide provide useful tests the hydroxide is soluble in excess alkali and is oxidised by air to the brown CoO(OH) . 

Addition of an alkali metal hydroxide solution to an aqueous solution of a nickel(II) salt precipitates a finely-divided green powder. nickel(II) hydroxide NilOHfj on heating this gives the black oxide. NiO. which is also obtained by heating nickel(II) carbonate or the hydrated nitrate. Black nickel(II) sulphide, NiS, is obtained by passing hydrogen sulphide into a solution of a nickel(II) salt. 

The anhydrous chloride is prepared by standard methods. It is readily soluble in water to give a blue-green solution from which the blue hydrated salt CuClj. 2H2O can be crystallised here, two water molecules replace two of the planar chlorine ligands in the structure given above. Addition of dilute hydrochloric acid to copper(II) hydroxide or carbonate also gives a blue-green solution of the chloride CuClj but addition of concentrated hydrochloric acid (or any source of chloride ion) produces a yellow solution due to formation of chloro-copper(ll) complexes (see below). 

Galena, see Eead sulfite Glauber s salt, see Sodium sulfate 10-water Goethite, see Iron(II) hydroxide oxide Goslarite, see Zinc sulfate 7-water Graham s salt, see Sodium phosphate(l —) Graphite, see Carbon... 

Iron(II) hydroxide [18624-44-7], Fe(OH)2, is prepared by precipitation of an iron(II) salt solution by strong base in the absence of air. It occurs as pale green, hexagonal crystals or a white amorphous powder. It is practically insoluble in water, fairly soluble in ammonium salt solutions, and soluble in acids and in concentrated NaOH solution. It is slowly oxidized by air. Conversion to Fe203 atH20 is eventually complete. 

In aqueous solutions, trivalent lanthanides ate very stable whereas only a limited number of lanthanides exhibit a stable divalent or tetravalent state. Practically, only Ce and Eu " exist in aqueous solutions. The properties of these cations ate very different from the properties of the trivalent lanthanides. For example, Ce" " is mote acidic and cetium(IV) hydroxide precipitates at pH 1. Eu " is less acidic and eutopium(II) hydroxide does not precipitate at pH 7—8.5, whereas trivalent lanthanide hydroxides do. Some industrial separations ate based on these phenomena. 

Cobalt(II) hydroxide [1307-86-4], Co(OH)2, is a pink, rhombic crystalline material containing about 61% cobalt. It is insoluble in water, but dissolves in acids and ammonium salt solutions. The material is prepared by mixing a cobalt salt solution and a sodium hydroxide solution. Because of the tendency of the cobalt(II) to oxidize, antioxidants (qv) are generally added. Dehydration occurs above 150°C. The hydroxide is a common starting material for the preparation of cobalt compounds. It is also used in paints and Hthographic printing inks and as a catalyst (see Paint). 

Copper Hydroxide. Copper(II) hydroxide [20427-59-2] Cu(OH)2, produced by reaction of a copper salt solution and sodium hydroxide, is a blue, gelatinous, voluminous precipitate of limited stabiUty. The thermodynamically unstable copper hydroxide can be kiaetically stabilized by a suitable production method. Usually ammonia or phosphates ate iacorporated iato the hydroxide to produce a color-stable product. The ammonia processed copper hydroxide (16—19) is almost stoichiometric and copper content as high as 64% is not uncommon. The phosphate produced material (20,21) is lower ia copper (57—59%) and has a finer particle size and higher surface area than the ammonia processed hydroxide. Other methods of production generally rely on the formation of an iasoluble copper precursor prior to the formation of the hydroxide (22—26). 

Chrom-hydrat, -hydroxyd, n. chromic hydroxide, chromium(lll) hydroxide, -hydroxydul, n. chromous hydroxide, chromium(II) hydroxide. 

Cbronioxydul-. chromous, chromium(II). -hy-drat, n. chromous hydroxide, chroinium(II) hydroxide. 8alz, n. chromous salt, chro-nuum(n) salt. verbiudung, /. chromous compound, chroinium(II) compound. 

Cupri-. cupric, copper(II). -azetst, n. cupric acetate, copper(II) acetate, -carbonat, n. cupric carbonate, copper(II) carbonate, -chlorid, n. cupric chloride, copper(II) chloride. -hydroxyd, n. cupric hydroxide, cop-per(II) hydroxide. -ion, n. cupric ion, copper(II) ion. -ozalat, n. cupric oxalate, copper(II) oxalate, -oxyd, n. cupric oxide, copper(II) oxide. -salz, n. cupric salt, copper(II) salt, -suifat, n. cupric sulfate. copper(II) sulfate, -sulfid, n. cupric sulfide, copper(II) sulfide, -verbihdung, /. cupric compound, copper(II) compound, -wein-saure, /. cupritartaric acid. 

Eisen-hydrozyd, n. ferric hydroxide, iron(III) hydroxide, -hydroxydul, n. ferrous hydroxide, iron(II) hydroxide. -jodid,n. iron iodide, specif, ferric iodide, iron(III) iodide, -jodiir, n. ferrous iodide, iron(II) iodide, -jodiirjo-did, n. ferrosoferric iodide, iron(II,IIl) iodide, kalium, n. potassium ferrate, -kaliumalaun,... 

Kupfer-hammerschlag, m. copper scale, -hoch-ofen, m. copper blast furnace, -hiitte,/. copper smeltery, -hydrat, n. copper hydroxide, -hydroxyd, n. copper hydroxide, specif, cupric hydroxide, copper(II) hydroxide, -hydroxy-dul, n. cuprous hydroxide, copper(I) hydroxide. 

Kupferoxyd, n. cupric oxide, copper(II) oxide, -ammoniak, n. ammoniacal copper oxide, cu-prammonium. -ammoniakkunstseide, -am-moniakzellulose, /. cuprammonium rayon, -hydrat, n. cupric hydroxide, copper(II) hydroxide. -salz, n. cupric salt, copper(II) salt. 

Manganoxydul-hydrat, n. manganous hydroxide, manganese (II) hydroxide, -oxyd, n. mangano-manganic oxide, manganese (II,III)... 

Nickel-hydroxyd, n. nickel hydroxide, -hy-droxydul, n. nickelous hydroxide, nickel(II) hydroxide. 

Jfickeloxydul, n. nickelous oxide, nickel(II) oxide, NiO. -hydrat, n, nickelous hydroxide, nickel (II) hydroxide, -salz, n. nickelous salt, nickel(II) salt, -verbindung,/. nickelous compound, nickel(II) compound. Nickelpapier, n. nickel foil, nickelplattiert, a. nickel-plated. 

Pallado-. palladous, palladium (II). -chlorid, n. palladous chloride, palladium(II) chloride, -chlorwasserstoffsaure, /. chloropalladous acid, chloropalladic(II) acid, -hydro d, n. palladous hydroxide, palladium(II) hydroxide. 

Zinn-hUtte,/. tin smeltery, tin works, -hydrat, n. tin hydroxide, -hydroxyd, n. tin hydroxide, specif, stannic hydroxide, tin(IV) hydroxide, -hydroxydul, n. stannous hydroxide, tin(II) hydroxide, -jodid, n. tin... 

Consider lead(II) hydroxide. It can be formed when solutions of lead(n) nitrate and potassium hydroxide are mixed. Its at a certain temperature is 4.2 X 1CT15. Assume volumes are additive in all cases. 

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