Lead(II) chromate

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Lead(II) chromate
Lead(II) chromate
Identifiers
CAS number 7758-97-6 YesY
PubChem 24460
EC number 231-846-0
UN number 3288
RTECS number GB2975000
Properties
Molecular formula PbCrO4
Molar mass 323.2 g/mol
Appearance orange-yellow powder
Density 6.12 g/cm3, solid
Melting point 844 °C
Solubility in water negligible
Solubility soluble in diluted nitric acid
insoluble in acetic acid, ammonia
Refractive index (nD) 2.31
Structure
Crystal structure monoclinic
Hazards
MSDS ICSC 0003
EU Index 082-004-00-2
EU classification Carc. Cat. 2
Repr. Cat. 1/3
Toxic (T)
Dangerous for the environment (N)
R-phrases R45, R61, R33, R62, R50/53
S-phrases S53, S45, S60, S61
NFPA 704
Flammability code 0: Will not burn. E.g., water Health code 3: Short exposure could cause serious temporary or residual injury. E.g., chlorine gas Reactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g., liquid nitrogen Special hazards (white): no codeNFPA 704 four-colored diamond
LD50 >12 g/kg (mouse, oral)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
 YesY (verify) (what is: YesY/N?)
Infobox references

Lead(II) chromate (PbCrO4) is a chemical compound, a chromate of lead. It has a vivid yellow color and is practically insoluble in water, and as a result, is used in paints under the name chrome yellow. It is commonly made in the laboratory by reacting a lead(II) salt (such as lead(II) nitrate) with a chromate or dichromate salt (such as potassium chromate or potassium dichromate) in solution in water, producing a very deep yellow to orange precipitate of lead(II) chromate.

Lead(II) chromate may also be known as chrome yellow, chromic acid lead(II) salt, canary chrome yellow 40-2250, chrome green, chrome green UC61, chrome green UC74, chrome green UC76, chrome lemon, crocoite, dianichi chrome yellow G, lemon yellow, king's yellow, Leipzig yellow, lemon yellow, Paris yellow, pigment green 15, plumbous chromate, pure lemon chrome L3GS, and various other names. The mineral crocoite, occurring as orange-yellow prismatic crystals, is a moderately rare mineral known from the oxidation zones of such Pb ore beds, that were affected by chromate-bearing solutions, coming from the oxidation of primary Cr minerals (chromite) of the nearby (ultra)mafic rocks.

Lead(II) chromate can be destroyed by strong reducing agents, combustibles, and organic materials.

Applications[edit]

Lead(II) chromate is used in some pyrotechnic compositions, especially delay compositions, as an oxidizer. Up to the late 1800s it was used to impart a bright yellow color to some types of candy.[1] It has also been used in the paint to color school buses.(Chrome Yellow)

Previously, its use was wider. Lead(II) chromate and "white lead", or lead(II) carbonate, were the most common lead-based paint pigments.

Preparation[edit]

Lead(II) chromate can be produced by reacting sodium chromate with lead(II) nitrate, or by reacting lead(II) monoxide with a chromic acid solution.

Reactions[edit]

Heating in hydroxide solution produces chrome red, a red or orange powder made by PbO and CrO3.

Also, in hydroxide solution lead chromate partially dissolves forming plumbite complex.

PbCrO4 + 4 OH-   →   [Pb(OH)4]2- + CrO42-

Safety hazards[edit]

Due to containing both lead and hexavalent chromium, lead(II) chromate is profoundly toxic.

Lead(II) chromate is a poison, and can be fatal if swallowed or inhaled.

Lead(II) chromate is a known carcinogen, developmental toxicant, and reproductive toxicant. It is also suspected that lead(II) chromate is a cardivascular or blood toxicant, immunotoxicant, kidney toxicant, neurotoxicant, respiratory toxicant, and a skin toxicant or sense organ toxicant.

If swallowed[edit]

Lead(II) chromate, historical dye collection of the Technical University of Dresden, Germany

If swallowed, lead(II) chromate poisoning can lead to abdominal pain and spasms, nausea, vomiting, and headaches. If the poisoning is not severe, one may experience lead line on the gums, a metallic taste, muscle weakness, and dizziness. The symptoms appear to get worse as the poisoning becomes more severe. Severe poisoning can lead to a coma and even death.

If inhaled[edit]

If inhaled, and the poisoning is not severe, one may experience symptoms such as a sore throat, coughing, shortness of breath, and labored breathing. Severe poisoning may lead to pulmonary edema, as well as several symptoms experienced from indigestion.

See also[edit]

References[edit]

  1. ^ Wisconsin. State Board of Health (1887). Progress Report of Public Health in Wisconsin, Volume 10. p. 92. Retrieved 17 July 2013.  (Google Books)