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These chemicals are expected to form gold-bridged dimers in a manner similar to titanium(IV) hydride. [15] Gold(II) compounds are usually diamagnetic with Au–Au bonds such as [Au(CH 2) 2 P(C 6 H 5) 2] 2 Cl 2. The evaporation of a solution of Au(OH) 3 in concentrated H 2 SO 4 produces red crystals of gold(II) sulfate, Au 2 (SO 4) 2.
Compounds of the metallic elements usually form simple aqua ions with the formula [M(H 2 O) n] z+ in low oxidation states. With the higher oxidation states the simple aqua ions dissociate losing hydrogen ions to yield complexes that contain both water molecules and hydroxide or oxide ions, such as the vanadium(IV) species [VO(H 2 O) 5] 2+.
Fulminating gold – a number of gold based explosives which "fulminate", or detonate easily. – gold hydrazide, formed by adding ammonia to the auric hydroxide. When dry, can explode on concussion. – an unstable gold carbonate formed by precipitation by potash from gold dissolved in aqua regia. Galena – lead(II) sulfide. Lead ore.
Aluminium hydroxide gels can be dehydrated (e.g. using water-miscible non-aqueous solvents like ethanol) to form an amorphous aluminium hydroxide powder, which is readily soluble in acids. Heating converts it to activated aluminas, which are used as desiccants , adsorbent in gas purification, and catalyst supports .
In hot concentrated hydrochloric acid, aluminium reacts with water with evolution of hydrogen, and in aqueous sodium hydroxide or potassium hydroxide at room temperature to form aluminates—protective passivation under these conditions is negligible. [9] The reaction with aqueous alkali is often written: [2] Al + NaOH + H 2 O → NaAlO 2 ...
The following chart shows the solubility of various ionic compounds in water at 1 atm pressure and room temperature (approx. 25 °C, 298.15 K). "Soluble" means the ionic compound doesn't precipitate, while "slightly soluble" and "insoluble" mean that a solid will precipitate; "slightly soluble" compounds like calcium sulfate may require heat to precipitate.
The reaction with hydrochloric acid is an equilibrium reaction that favors formation of tetrachloroaurate(III) anions. This results in a removal of gold ions from solution and allows further oxidation of gold to take place. The gold dissolves to become chloroauric acid. In addition, gold may be dissolved by the chlorine present in aqua regia.
The water molecule is amphoteric in aqueous solution. It can either gain a proton to form a hydronium ion H 3 O +, or else lose a proton to form a hydroxide ion OH −. [7] Another possibility is the molecular autoionization reaction between two water molecules, in which one water molecule acts as an acid and another as a base. H 2 O + H 2 O ...