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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]
At 25 °C (77 °F), solutions of which the pH is less than 7 are acidic, and solutions of which the pH is greater than 7 are basic. Solutions with a pH of 7 at 25 °C are neutral (i.e. have the same concentration of H + ions as OH − ions, i.e. the same as pure water). The neutral value of the pH depends on the temperature and is lower than 7 ...
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)
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 .
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 aqueous solution is a solution in which the solvent is water. It is mostly shown in chemical equations by appending (aq) to the relevant chemical formula . For example, a solution of table salt , also known as sodium chloride (NaCl), in water would be represented as Na + (aq) + Cl − (aq) .
The cationic metal centres act as Lewis acid sites while the anionic oxygen centres act as Lewis bases. Surface hydroxyl groups can serve as Brønsted acid or base sites as they can give up or accept a proton. [14] The surface of most metal oxides will be, to some extent, hydroxylated under normal conditions when water vapor is present. [15]