Sulfuric Acid → Dichromate ion

HRID 275240

Reaction equation

HRID 275240 reaction equation
[Cr:1]([O-:5])([O-:4])(=[O:3])=[O:2].[Na+:6].[Na+].S(=O)(=O)(O)O.S(=O)(=O)(O)[O-].[Na+]>>[O-:2][Cr:1]([O:5][Cr:1]([O-:4])(=[O:3])=[O:2])(=[O:4])=[O:3].[Na+:6].[Na+:6].[O-:2][Cr:1]([O:5][Cr:1]([O-:4])(=[O:3])=[O:2])(=[O:4])=[O:3]

Participants

5

Reactant 3

HCID 1118Sulfuric AcidHCID 24488Sodium ChromateHCID 516919Sodium Bisulfate

Product 2

HCID 24503Dichromate ionHCID 25408Sodium Dichromate

Procedure

Chromic acid and sodium bichromate or sodium chromate are made by roasting chromium-containing ore with soda ash (sodium carbonate) or sodium hydroxide to form sodium chromate. The roasted ore is quenched in water and the soluble sodium chromate dissolves in the water to form "yellow liquor." The sodium chromate is reacted with sulfuric acid or sodium bisulfate to produce sodium bichromate (the "bichromate process"). Upon evaporation, by-product sodium sulfate crystallizes and is filtered off. Because it is contaminated with about 200 to about 1600 ppm of hexavalent chromium, it can be sold only to low value markets such as the pulp and paper industry, and the chromium values in it are lost. Increasingly, environmental considerations limit the sale of sodium sulfate to a maximum chromium contamination of 1000 ppm.

Workup

  1. customThe roasted ore is quenched in water
  2. dissolutionthe soluble sodium chromate dissolves in the water
  3. customto form "yellow liquor

Sources & evidence

ORD record
ord-f2cc05832eb047f88a8517266b7c8eb5
Source dataset
uspto-grants-1995_02
Patent number
US05393503

Linked notes

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