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Encyclopedia > Chromic acid
Chromic acid
Image:Chromic_acid.PNG, Image:Dichromic_acid.PNG
General
Systematic name  ?
Molecular formula H2CrO4
SMILES  ?
Molar mass  ?
Appearance  ?
CAS number  ?
Properties
Density and phase  ?
Solubility in water  ?
Melting point  ?
Boiling point  ?
Acidity (pKa)  ?
Hazards
MSDS External MSDS
EU classification  ?
NFPA 704  ?
R-phrases  ?
S-phrases  ?
RTECS number  ?
Supplementary data page
Structure & properties n, εr, etc.
Thermodynamic data Phase behaviour
Solid, liquid, gas
Spectral data UV, IR, NMR, MS
Related compounds Sodium chromate
Potassium chromate
Except where noted otherwise, data are given for
materials in their standard state (at 25°C, 100 kPa)
Infobox disclaimer and references

In chemistry, chromic acid is a chromium (Cr) compound, yet to be isolated, with the formula H2CrO4. A related acid, also yet to be isolated, is dichromic acid with the formula H2Cr2O7. Although these acids are not available in a pure state, their conjugate bases, chromate and dichromate form well characterized salts. The acid anhydride of chromic acid is chromium trioxide, also called chromium(VI) oxide; industrially, this compound is sometimes sold as "chromic acid". Image File history File links Chromic_acid. ... Image File history File links Dichromic_acid. ... IUPAC nomenclature is a system of naming chemical compounds and of describing the science of chemistry in general. ... A chemical formula (also called molecular formula) is a concise way of expressing information about the atoms that constitute a particular chemical compound. ... The simplified molecular input line entry specification or SMILES is a specification for unambiguously describing the structure of chemical molecules using short ASCII strings. ... Molar mass is the mass of one mole of a chemical element or chemical compound. ... CAS registry numbers are unique numerical identifiers for chemical compounds, polymers, biological sequences, mixtures and alloys. ... In physics, density is defined as mass m per unit volume V. For the common case of a homogeneous substance, it is expressed as: where, in SI units: ρ (rho) is the density of the substance, measured in kg·m-3 m is the mass of the substance, measured in kg... In the physical sciences, a phase is a set of states of a macroscopic physical system that have relatively uniform chemical composition and physical properties (i. ... It has been suggested that this article or section be merged with Solution. ... This article describes water from a scientific and technical perspective. ... The melting point of a crystalline solid is the temperature at which it changes state from solid to liquid. ... The boiling point of a substance is the temperature at which it can change its state from a liquid to a gas throughout the bulk of the liquid at a given pressure. ... In chemistry and biochemistry, the acid dissociation constant, the acidity constant, or the acid-ionization constant (Ka) is a specific type of equilibrium constant that indicates the extent of dissociation of hydronium ions from an acid. ... An example MSDS in a US format provides guidance for handling a hazardous substance and information on its composition and properties. ... Council Directive 67/548/EEC of 27 June 1967 on the approximation of laws, regulations and administrative provisions relating to the classification, packaging and labelling of dangerous substances (as amended) is the main source of European Union law concerning chemical safety. ... NFPA 704 is a standard maintained by the U.S. National Fire Protection Association. ... R-phrases are defined in Annex III of European Union Directive 67/548/EEC: Nature of special risks attributed to dangerous substances and preparations. ... S-phrases are defined in Annex IV of European Union Directive 67/548/EEC: Safety advice concerning dangerous substances and preparations. ... RTECS, also known as Registry of Toxic Effects of Chemical Substances, is a database of toxicity information compiled from the open scientific literature that is available for charge. ... The refractive index (or index of refraction) of a medium is a measure for how much the speed of light (or other waves such as sound waves) is reduced inside the medium. ... The dielectric constant εr (represented as or K in some cases) is defined as the ratio: where εs is the static permittivity of the material in question, and ε0 is the vacuum permittivity. ... Ultraviolet-Visible Spectroscopy or Ultraviolet-Visible Spectrophotometry (UV/ VIS) involves the spectroscopy of photons (spectrophotometry). ... Infrared spectroscopy (IR Spectroscopy) is the subset of spectroscopy that deals with the infrared region of the electromagnetic spectrum. ... It has been suggested that NMR Data Processing be merged into this article or section. ... Mass spectrometry (also known as mass spectroscopy (deprecated)[1] or in common speech mass-spec) is an analytical technique used to measure the mass-to-charge ratio of ions. ... Potassium Chromate is a yellow chemical indicator used for Identifying concentrations of Chloride ions in a salt solution with Silver nitrate. ... In chemistry, the standard state of a material is its state at 1 bar (100 kilopascals) and 25 degrees Celsius (298. ... General Name, Symbol, Number chromium, Cr, 24 Chemical series transition metals Group, Period, Block 6, 4, d Appearance silvery metallic Atomic mass 51. ... A chemical compound is a chemical substance consisting of two or more different chemically bonded chemical elements, with a fixed ratio determining the composition. ... A chemical formula (also called molecular formula) is a concise way of expressing information about the atoms that constitute a particular chemical compound. ... Acidity redirects here. ... A sample of ammonium dichromate Chromates and dichromates are salts of chromic acid and dichromic acid, respectively. ... Chromates and Dichromates are salts of chromic acid. ... Acid anhydrides are chemical compounds that look like, and sometimes are, the product resulting from dehydration of an acid. ... In chemistry, chromic acid (or Jones reagent) is a chromium (Cr) compound, yet to be isolated, that would have the formula H2CrO4. ...


In all chromic acid and its direct derivatives, the element chromium is in oxidation state +6 (or VI). Chromium(VI) is often referred to as hexavalent chromium. Although chromium can exist in a number of oxidation states, hexavalent chromium is commonly reduced in redox reactions to the [[Cr(H2O)6]]3+ ion, which has a distinctive blue green colour. Hexavalent chromium compounds are toxic and carcinogenic. The periodic table of the chemical elements A chemical element, or element for short, is a type of atom that is defined by its atomic number; that is, by the number of protons in its nucleus. ... In chemistry, the oxidation state is an indicator of the degree of oxidation of an atom in a chemical compound. ... The most fundamental reactions in chemistry are the redox processes. ... Valence, also known as valency or valency number, is a measure of the number of chemical bonds formed by the atoms of a given element. ... Toxic redirects here, but this is also the name of a song by Britney Spears; see Toxic (song) Look up toxic and toxicity in Wiktionary, the free dictionary. ... In pathology, a carcinogen is any substance or agent that promotes cancer. ...


Chromic acid solutions are generated by acidifying aqueous solutions of chromate or dichromate salts. These solutions tend to be powerful oxidants, capable of oxidizing organics in glassware and often used for the cleaning of glass. Such solutions are often red-brown, orange, or yellow-coloured, depending on the concentration of the chromium(VI). European Union Chemical hazard symbol for oxidizing agents Dangerous goods label for oxidising agents An oxidizing agent (also called an oxidant or oxidizer) is referred to as A chemical compound that readily transfers oxygen atoms or A substance that gains electrons in a redox chemical reaction. ... Benzene is the simplest of the arenes, a family of organic compounds An organic compound is any member of a large class of chemical compounds whose molecules contain carbon and hydrogen; therefore, carbides, carbonates, carbon oxides and elementary carbon are not organic (see below for more on the definition controversy... Brown glass jars with some clear lab glassware in the background Laboratory glassware refers to a variety of equipment, traditionally made of glass, used for scientific experiments and other work in science, especially in chemistry and biology laboratories. ... In chemistry, concentration is the measure of how much of a given substance there is mixed with another substance. ...

Contents

Uses

As cleaning solution

A mixture of a solution of 140 g of sodium dichromate dihydrate in 100 mL of distilled water and 2 L of sulphuric acid can be used to clean glassware.[1] Note that the preparation of this solution is hazardous and should be done in a cold water bath in a fume hood.[citation needed] In many countries this method is deprecated, since the resulting solution is highly corrosive, and high valent chromium species (some of which are rather volatile[citation needed]) are carcinogenic.[citation needed] Moreover, there are other cleaning methods that are just as effective, safer, and more environmentally friendly. Sodium dichromate is a chemical, formula Na2Cr2O7. ... Distilled water is water that has virtually all of its impurities removed through distillation (boiling the water and re-condensing the steam into a clean container, leaving contaminants behind). ... Sulfuric acid (British English: sulphuric acid), H2SO4, is a strong mineral acid. ... A common modern fume hood. ... Corrosion is the destructive reaction of a metal with another material, e. ... Look up volatile in Wiktionary, the free dictionary. ... In pathology, a carcinogen is any substance or agent that promotes cancer. ...


Other uses

Chromic acid is used to make chromates, oxidizing agents, catalysts; chromium plating intermediate; used to make ceramic glazes and colored glass; used in metal cleaning; used in inks, paints, and tanning; used in engraving and photography. Chromium trioxide has been classified as "select carcinogen" and long term exposure can cause ulceration of the respiratory system and skin.


Reactions

In organic chemistry, dilute solutions of hexavalent chromium can be used to oxidize primary or secondary alcohols to the corresponding aldehydes and ketones. Chromic acid in the presence of aqueous sulfuric acid and acetone is known as the Jones reagent, which will oxidize primary and secondary alcohols to carboxylic acids and ketones respectively, while rarely affecting unsaturated bonds. Chromium trioxide and pyridinium hydrochloride (pyridine neutralized by HCl) form the pyridinium chlorochromate reagent. When a primary alcohol is treated with anhydrous pyridinium chlorochromate in methylene chloride, the oxidation of the -CH2OH group in primary alcohols will stop at the aldehyde group (-CHO).[1] In contrast, other oxidizing solutions, such as aqueous potassium permanganate, will have a tendency to oxidize the -CH2OH group all the way to a carboxyl group (-COOH). Dilute hexavalent chromium solutions will not oxidize a tertiary alcohol hydroxyl group. Because of the color change from a variation of orange to a blue-green color, a hexavalent chromium reagent can be formulated as a qualitative analytical test for the presence of primary or secondary alcohols. For example, chromium trioxide dissolved in aqueous sulfuric acid solution has been used as such a test reagent.[1] Potassium dichromate, when added to concentrated sulfuric acid in the presence of chloride ions and heated strongly, produces red fumes that condense to form a red liquid - chromyl chloride, CrO2Cl2. This compound hydrolyses in water to form aqueous chromic and hydrochloric acids: CrO2Cl2(l) + 2H2O(l) → H2CrO4(aq) + 2HCl(aq) As bromides and iodides do not give respective analogues, the test is specific for chlorides. Organic chemistry is a specific discipline within chemistry which involves the scientific study of the structure, properties, composition, reactions, and preparation (by synthesis or by other means) of chemical compounds consisting of primarily carbon and hydrogen, which may contain any number of other elements, including nitrogen, oxygen, halogens as well... Dissolving table salt in water This article is about a chemical solution; for other uses of the term solution, see solution (disambiguation). ... Functional group of an alcohol molecule. ... An aldehyde. ... Ketone group A ketone is either the functional group characterized by a carbonyl group linked to two other carbon atoms or a chemical compound that contains this functional group. ... Sulfuric acid, H2SO4, is a strong mineral acid. ... In chemistry, chromic acid (or Jones reagent) is a chromium (Cr) compound, yet to be isolated, that would have the formula H2CrO4. ... Structure of a carboxylic acid The 3D structure of the carboxyl group A space-filling model of the carboxyl group Carboxylic acids are organic acids characterized by the presence of a carboxyl group, which has the formula -C(=O)OH, usually written -COOH or -CO2H. [1] Carboxylic acids are Bronsted... Ketone group A ketone is either the functional group characterized by a carbonyl group linked to two other carbon atoms or a chemical compound that contains this functional group. ... Pyridine is a chemical compound with the formula C5H5N. It is a liquid with a distinctively sour odour. ... R-phrases , S-phrases , , , , Flash point non-flammable Supplementary data page Structure and properties n, εr, etc. ... Pyridinium chlorochromate, a reddish orange solid reagent, is used to oxidize primary alcohols to aldehydes and secondary alcohols to ketones. ... Dichloromethane or Methylene chloride is a chemical compound widely used as a solvent for organic materials. ... An aldehyde. ... Potassium permanganate is the chemical compound KMnO4. ... In chemistry, a carboxyl group is a functional group consisting of a carbon atom doubly bonded to an oxygen atom and single-bonded to a hydroxyl (-OH) group, typically written as -COOH: where R is a hydrogen or an organic group. ... A reagent or reactant is any substance used in a chemical reaction. ... Sulfuric acid, H2SO4, is a strong mineral acid. ... Potassium dichromate, K2Cr2O7 is used in oxidation reactions. ... Sulfuric acid, H2SO4, is a strong mineral acid. ... The chloride ion is formed when the element chlorine picks up one electron to form an anion (negatively-charged ion) Cl−. The salts of hydrochloric acid HCl contain chloride ions and are also called chlorides. ... Chromyl chloride is a chemical compound with the formula CrO2Cl2. ... General Name, Symbol, Number bromine, Br, 35 Series halogens Group, Period, Block 17 (VIIA), 4, p Density, Hardness 3119 kg/m3 (300 K), NA Appearance Gas: red-brown solid: metallic luster Atomic properties Atomic weight 79. ... General Name, Symbol, Number iodine, I, 53 Chemical series halogens Group, Period, Block 17, 5, p Appearance violet-dark gray, lustrous Atomic mass 126. ...


References

  1. Alcohols from Carbonyl Compounds: Oxidation-Reduction and Organometallic Compounds (PDF)
  2. Index of Organic Synthesis procedures utilizing Chromic acid

PDF is an abbreviation with several meanings: Portable Document Format Post-doctoral fellowship Probability density function There also is an electronic design automation company named PDF Solutions. ...

External links

  • International Chemical Safety Card 1194
  • National Pollutant Inventory - Chromium (III) compounds fact sheet
  • NIOSH Pocket Guide to Chemical Hazards
  • IARC Monograph "Chromium and Chromium compounds"
  • Links to external chemical sources

  Results from FactBites:
 
Chromic acid - Wikipedia, the free encyclopedia (729 words)
While these acids are not available, they are known through their divalent anions (chromate and dichromate respectively) and the compounds formed from them.
Chromic acid solutions are generally acidified aqueous solutions of chromate or dichromate salts.
Chromic acid in the presence of aqueous sulfuric acid is known as the Jones reagent, and will oxidize primary and secondary alcohols to carboxylic acids and ketones, respectively.
Plating Resources, Inv. provides chrome plating chemicals and plating services. (502 words)
In addition, HCP grade chromic acid is a non dusting material that is also very easy to pour and resists caking.
HCP Grade Chromic Acid is unconditionally warranted as to the purity specified.
Chromic acid is a strong oxidizer so contact with organic materials and reducing agents must be avoided.
  More results at FactBites »

 
 

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