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Sodium aluminate is an inorganic chemical that is used as an effective source of aluminium hydroxide for many industrial and technical applications. Pure sodium aluminate is a white crystalline solid having a formula variously given as NaAlO 2, NaAl(OH) 4 (), [3] Na 2 O·Al 2 O 3, or Na 2 Al 2 O 4.
The relevant reactions are: 3 NaAlH 4 → Na 3 AlH 6 + 2 Al + 3 H 2 Na 3 AlH 6 → 3 NaH + Al + 3/2 H 2. Sodium tetrahydroaluminate can release up to 7.4 wt % of hydrogen when heated at 200 °C (392 °F). Absorption can be slow, with several minutes being required to fill a tank. Both release and uptake are catalysed by titanium. [5]
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 ...
Aluminates are often formulated as a combination of basic oxide and aluminium oxide, for example the formula of anhydrous sodium aluminate NaAlO 2 would be shown as Na 2 O·Al 2 O 3. A number of aluminate oxyanions are known: The simplest is the approximately tetrahedral AlO 5− 4 found in the compound Na 5 AlO 4, [2] framework AlO −
The polymorphs differ in terms of the stacking of the layers. All forms of Al(OH) 3 crystals are hexagonal [disputed – discuss]: gibbsite is also known as γ-Al(OH) 3 [8] or α-Al(OH) 3 [citation needed] bayerite is also known as α-Al(OH) 3 [8] or β-alumina trihydrate [citation needed] nordstrandite is also known as Al(OH) 3 [8] doyleite
Sodium bis(2-methoxyethoxy)aluminium hydride (SMEAH; [1] trade names Red-Al, Synhydrid, Vitride) is a hydride reductant with the formula NaAlH 2 (OCH 2 CH 2 OCH 3) 2. The trade name Red-Al refers to its being a reducing aluminium compound. It is used predominantly as a reducing agent in organic synthesis.
Aluminium oxide is an amphoteric substance, meaning it can react with both acids and bases, such as hydrofluoric acid and sodium hydroxide, acting as an acid with a base and a base with an acid, neutralising the other and producing a salt. Al 2 O 3 + 6 HF → 2 AlF 3 + 3 H 2 O Al 2 O 3 + 2 NaOH + 3 H 2 O → 2 NaAl(OH) 4 (sodium aluminate)
For many substances, the formation reaction may be considered as the sum of a number of simpler reactions, either real or fictitious. The enthalpy of reaction can then be analyzed by applying Hess' law, which states that the sum of the enthalpy changes for a number of individual reaction steps equals the enthalpy change of the overall reaction.