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Vanadium(III) oxide is the inorganic compound with the formula V 2 O 3.It is a black solid prepared by reduction of V 2 O 5 with hydrogen or carbon monoxide. [3] [4] It is a basic oxide dissolving in acids to give solutions of vanadium (III) complexes. [4]
In strongly acidic solutions, pH < 2, [VO 2 (H 2 O) 4] + is the predominant species, while the oxide V 2 O 5 precipitates from solution at high concentrations. The oxide is formally the acid anhydride of vanadic acid. The structures of many vanadate compounds have been determined by X-ray crystallography.
If acid is slowly added to a solution of Na 3 VO 4, the colour gradually deepens through orange to red before brown hydrated V 2 O 5 precipitates around pH 2. These solutions contain mainly the ions HVO 4 2− and V 2 O 7 4− between pH 9 and pH 13, but below pH 9 more exotic species such as V 4 O 12 4− and HV 10 O 28 5− ( decavanadate ...
An acidic oxide is an oxide that either produces an acidic solution upon addition to water, or acts as an acceptor of hydroxide ions effectively functioning as a Lewis acid. [1] Acidic oxides will typically have a low pK a and may be inorganic or organic .
A basic oxide, also called a base anhydride (meaning "base without water"), is usually formed in the reaction of oxygen with metals, especially alkali (group 1) and alkaline earth (group 2) metals. Both of these groups form ionic oxides that dissolve in water to form basic solutions of the corresponding metal hydroxide: Alkali metals (Group 1)
When dissolved in water, many metallic oxide form alkaline solutions, while many oxides of nonmetals form acidic solutions. For example, sodium oxide in solution forms the strong base sodium hydroxide, while phosphorus pentoxide in solution forms phosphoric acid. [7] Oxygenated anions such as chlorates (ClO − 3), perchlorates (ClO − 4 ...
Vanadium(IV) oxide or vanadium dioxide is an inorganic compound with the formula VO 2.It is a dark blue solid. Vanadium(IV) dioxide is amphoteric, dissolving in non-oxidising acids to give the blue vanadyl ion, [VO] 2+ and in alkali to give the brown [V 4 O 9] 2− ion, or at high pH [VO 4] 4−. [4]
The general mechanism for acidic and alkaline solutions is shown below. Under acidic conditions water binds to the surface with the irreversible removal of one electron and one proton to form a platinum hydroxide. [4] In an alkaline solution a reversible binding of hydroxide ion coupled to a one electron oxidation is thought to precede a ...