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Sodium dichromate is the inorganic compound with the formula Na 2 Cr 2 O 7. However, the salt is usually handled as its dihydrate Na 2 Cr 2 O 7 ·2 H 2 O . Virtually all chromium ore is processed via conversion to sodium dichromate and virtually all compounds and materials based on chromium are prepared from this salt. [ 1 ]
Sodium nitroprusside – Na 2 [Fe(CN) 5 NO]·2H 2 O; Sodium oxide – Na 2 O; Sodium perborate – NaBO 3 ·H 2 O; Sodium perbromate – NaBrO 4; Sodium percarbonate – 2Na 2 CO 3 ·3H 2 O 2; Sodium perchlorate – NaClO 4; Sodium periodate – NaIO 4; Sodium permanganate – NaMnO 4; Sodium peroxide – Na 2 O 2; Sodium peroxycarbonate – Na ...
For example, from Fe 2+ + 2 e − ⇌ Fe(s) (–0.44 V), the energy to form one neutral atom of Fe(s) from one Fe 2+ ion and two electrons is 2 × 0.44 eV = 0.88 eV, or 84 907 J/(mol e −). That value is also the standard formation energy (∆ G f °) for an Fe 2+ ion, since e − and Fe( s ) both have zero formation energy.
4) and dichromate (Cr 2 O 7 2−) anions are the principal ions at this oxidation state. They exist at an equilibrium, determined by pH: 2 [CrO 4] 2− + 2 H + ⇌ [Cr 2 O 7] 2− + H 2 O. Chromium(VI) oxyhalides are known also and include chromyl fluoride (CrO 2 F 2) and chromyl chloride (CrO 2 Cl 2). [6]
The chromate and dichromate ions are fairly strong oxidizing agents. Commonly three electrons are added to a chromium atom, reducing it to oxidation state +3. In acid solution the aquated Cr 3+ ion is produced. Cr 2 O 2− 7 + 14 H + + 6 e − → 2 Cr 3+ + 7 H 2 O ε 0 = 1.33 V. In alkaline solution chromium(III) hydroxide is produced.
Aluminium carbonate (Al 2 (CO 3) 3), is a carbonate of aluminium.It is not well characterized; one authority says that simple carbonates of aluminium are not known. [2] However related compounds are known, such as the basic sodium aluminium carbonate mineral dawsonite (NaAlCO 3 (OH) 2) and hydrated basic aluminium carbonate minerals scarbroite (Al 5 (CO 3)(OH) 13 •5(H 2 O)) and ...
For lab and small scale preparations a mixture of chromite ore, sodium hydroxide and sodium nitrate reacting at lower temperatures may be used (even 350 C in the corresponding potassium chromate system). [2] Subsequent to its formation, the chromate salt is converted to sodium dichromate, the precursor to most chromium compounds and materials. [3]
The ion/molecule/atom surrounding the central ion/molecule/atom is called a ligand. This number is determined somewhat differently for molecules than for crystals. For molecules and polyatomic ions the coordination number of an atom is determined by simply counting the other atoms to which it is bonded (by either single or multiple bonds). [1]