Chromate

Revision as of 23:50, 8 August 2012 by WikiBot (talk | contribs) (Bot: Automated text replacement (-{{SIB}} + & -{{EH}} + & -{{EJ}} + & -{{Editor Help}} + & -{{Editor Join}} +))
(diff) ← Older revision | Latest revision (diff) | Newer revision → (diff)
Jump to navigation Jump to search

WikiDoc Resources for Chromate

Articles

Most recent articles on Chromate

Most cited articles on Chromate

Review articles on Chromate

Articles on Chromate in N Eng J Med, Lancet, BMJ

Media

Powerpoint slides on Chromate

Images of Chromate

Photos of Chromate

Podcasts & MP3s on Chromate

Videos on Chromate

Evidence Based Medicine

Cochrane Collaboration on Chromate

Bandolier on Chromate

TRIP on Chromate

Clinical Trials

Ongoing Trials on Chromate at Clinical Trials.gov

Trial results on Chromate

Clinical Trials on Chromate at Google

Guidelines / Policies / Govt

US National Guidelines Clearinghouse on Chromate

NICE Guidance on Chromate

NHS PRODIGY Guidance

FDA on Chromate

CDC on Chromate

Books

Books on Chromate

News

Chromate in the news

Be alerted to news on Chromate

News trends on Chromate

Commentary

Blogs on Chromate

Definitions

Definitions of Chromate

Patient Resources / Community

Patient resources on Chromate

Discussion groups on Chromate

Patient Handouts on Chromate

Directions to Hospitals Treating Chromate

Risk calculators and risk factors for Chromate

Healthcare Provider Resources

Symptoms of Chromate

Causes & Risk Factors for Chromate

Diagnostic studies for Chromate

Treatment of Chromate

Continuing Medical Education (CME)

CME Programs on Chromate

International

Chromate en Espanol

Chromate en Francais

Business

Chromate in the Marketplace

Patents on Chromate

Experimental / Informatics

List of terms related to Chromate


File:Potassium-chromate-sample.jpg
A sample of potassium chromate
A sample of potassium dichromate

Overview

Chromates and dichromates are salts of chromic acid and dichromic acid, respectively. Chromate salts contain the chromate ion, CrO42−, and have an intense yellow color. Dichromate salts contain the dichromate ion, Cr2O72−, and have an intense orange color.

Characteristics

2 CrO42− + 2 H3O+ ⇌ Cr2O72− + 3 H2O
This equilibrium can be pushed towards dichromate by lowering the pH (making the solution more acidic) or in the other direction towards chromate by raising the pH to basic. This is a classic example of Le Chatelier's principle at work.
  • They are used in environmental analysis to measure chemical oxygen demand (COD).
  • They are carcinogenic. All hexavalent chromium compounds are considered toxic and carcinogenic.
  • When used as oxidizing agents or titrants in a redox chemical reaction, they will turn into trivalent chromium, Cr3+, which has a distinctively different blue-green color.
  • The sodium (Na+), potassium (K+), and ammonium (NH4+) salts are water soluble granular solids and are the most commonly used chromate or dichromate chemical reagents. Most chromate and dichromate salts of heavy metals, lanthanides or alkaline earth metals are only very slightly soluble in water and are thus of much less usefulness.
  • Chromate conversion coatings are applied to metals for corrosion protection, and to improve paint adhesion.
  • The use of chromate compounds in manufactured goods is restricted in the EU (and by market commonality the rest of the world) by EU Parliament directive 2002/95/EC

Structures

File:Chromate-3D-balls.png
File:Chromate-2D-dimensions.png
File:Dichromate-3D-balls.png
File:Dichromate-2D-dimensions.png
the tetrahedral chromate ion, CrO42−
the dichromate ion, Cr2O72−, consists of two corner-sharing tetrahedra

See also

External links

de:Chromate he:כרומט nl:Chromateren

Template:WS