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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 ·2H 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]
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It is however produced on a large scale industrially. Virtually all chromium ore is processed via the formation of hexavalent chromium, specifically the salt sodium dichromate. [2] Sodium chromate is converted into other hexavalent chromium compounds such as chromium trioxide and various salts of chromate and dichromate.
Chromium trioxide is generated by treating sodium dichromate with sulfuric acid: [6] H 2 SO 4 + Na 2 Cr 2 O 7 → 2 CrO 3 + Na 2 SO 4 + H 2 O. Approximately 100,000 tonnes are produced annually by this or similar routes. [7] The solid consists of chains of tetrahedrally coordinated chromium atoms that share vertices.
The change in equilibrium is visible by a change from yellow (chromate) to orange (dichromate), such as when an acid is added to a neutral solution of potassium chromate. At yet lower pH values, further condensation to more complex oxyanions of chromium is possible. Both the chromate and dichromate anions are strong oxidizing reagents at low pH ...
sodium oxybate (C 4 H 7 NO) n: Poly(N-vinylacetamide) Poly(N-vinylacetamide) C 4 H 7 NO 2: 1-Aminocyclopropanecarboxylic acid: 22059-21-8 C 4 H 7 NO 3: aceturic acid: C 4 H 7 NO 4: aspartic acid Asp: 56-84-8 C 4 H 8: cyclobutane: 287-23-0 C 4 H 8 N 2 O 3: asparagine Asn: 70-47-3 C 4 H 8 O: tetrahydrofuran THF: 109-99-9 C 4 H 8 O 2: ethyl ...
This process is done by putting zinc or a zinc plated metal in a solution of sodium dichromate and sulfuric acid for a few seconds. [6] Zinc chromate can also be synthesized by using neutral potassium chromate (K 2 CrO 4) and zinc sulfate (ZnSO 4), which forms a precipitate. [7] K 2 CrO 4 + ZnSO 4 → ZnCrO 4 + K 2 SO 4
Strontium chromate is approximately 30 times more soluble in water at 100 °C than at room temperature. Therefore, the yellow strontium chromate can be suspended in a hot solution of a soluble sulfate to digest until fully converted to the much less soluble and white strontium sulfate, leaving the chromate or dichromate in solution.