Barium carbonate

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Barium carbonate
Skeletal formula of barium carbonate
Powder of barium carbonate
Identifiers
CAS number 513-77-9 YesY
PubChem 10563
ChemSpider 10121 YesY
UNII 6P669D8HQ8 YesY
EC number 208-167-3
UN number 1564
RTECS number CQ8600000
Jmol-3D images Image 1
Image 2
Properties
Molecular formula CBaO3
Molar mass 197.34 g mol−1
Appearance white crystals
Odor odorless
Density 4.286 g/cm3
Melting point 811 °C (1,492 °F; 1,084 K)
polymorphic transformation
Boiling point 1,450 °C (2,640 °F; 1,720 K)
decomposes[1] from 1360 °C
Solubility in water 16 mg/L (8.8°C)
22 mg/L (18 °C)
24 mg/L (20 °C)
24 mg/L (24.2 °C)[1]
Solubility product, Ksp 2.58·10-9
Solubility decomposes in acid
insoluble in ethanol
Refractive index (nD) 1.676
Thermochemistry
Specific
heat capacity
C
85.35 J/mol·K[1]
Std molar
entropy
So298
112 J/mol·K[2]
Std enthalpy of
formation
ΔfHo298
-1219 kJ/mol[2]
Gibbs free energy ΔG -1139 kJ/mol[1]
Hazards
MSDS ICSC 0777
GHS pictograms The exclamation-mark pictogram in the Globally Harmonized System of Classification and Labelling of Chemicals (GHS)[3]
GHS signal word Warning
GHS hazard statements H302[3]
EU Index 056-003-00-2
EU classification Harmful Xn
R-phrases R22
S-phrases (S2), S24/25
NFPA 704
Flammability code 0: Will not burn. E.g., water Health code 2: Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. E.g., chloroform Reactivity code 1: Normally stable, but can become unstable at elevated temperatures and pressures. E.g., calcium Special hazards (white): no codeNFPA 704 four-colored diamond
Flash point Non-flammable
LD50 418 mg/kg, oral (rat)
Related compounds
Other cations Magnesium carbonate
Calcium carbonate
Strontium carbonate
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

Barium carbonate (BaCO3), also known as witherite, is a chemical compound used in rat poison, bricks, ceramic glazes and cement.

Witherite[edit]

Witherite crystallizes in the orthorhombic system. The crystals are invariably twinned together in groups of three, giving rise to pseudo-hexagonal forms somewhat resembling bipyramidal crystals of quartz, the faces are usually rough and striated horizontally.[4] It transforms into an hexagonal phase at 1084 K that changes into a cubic phase at 1254 K.

Witherite

The mineral is named after William Withering, who in 1784 recognized it to be chemically distinct from barytes.[5] It occurs in veins of lead ore at Hexham in Northumberland, Alston in Cumbria, Anglezarke, near Chorley in Lancashire and a few other localities. Witherite is readily altered to barium sulfate by the action of water containing calcium sulfate in solution and crystals are therefore frequently encrusted with barytes. It is the chief source of barium salts and is mined in considerable amounts in Northumberland. It is used for the preparation of rat poison, in the manufacture of glass and porcelain, and formerly for refining sugar.[4] It is also used for controlling the chromate to sulfate ratio in chromium electroplating baths.[6]

Preparation[edit]

Barium carbonate is made commercially from barium sulfide either by treatment with sodium carbonate at 60 to 70 °C (soda ash method) or by passing carbon dioxide at 40 to 90 °C.

In the soda ash process, solid or dissolved sodium carbonate is added to barium sulfide solution, and the barium carbonate precipitate is filtered, washed and dried. In the barium carbonate molecule, two oxygen atoms gain one electron each from Ba atom.[7]

Reactions[edit]

Barium carbonate reacts with acids such as hydrochloric acid to form soluble barium salts, such as barium chloride:

BaCO
3
(s) + 2 HCl(aq)BaCl
2
(aq) + CO
2
(g) + H
2
O
(l)

However, the reaction with sulfuric acid is poor, because barium sulfate is highly insoluble.

Uses[edit]

Barium carbonate is widely used in the ceramics industry as an ingredient in glazes. It acts as a flux, a matting and crystallizing agent and combines with certain colouring oxides to produce unique colours not easily attainable by other means. Its use is somewhat controversial since some claim that it can leach from glazes into food and drink. To provide a safe means of use, BaO is often used in fritted form.

In the brick, tile, earthenware and pottery industries barium carbonate is added to clays to precipitate soluble salts (calcium sulfate and magnesium sulfate) that cause efflorescence.

References[edit]

  1. ^ a b c d http://chemister.ru/Database/properties-en.php?dbid=1&id=377
  2. ^ a b Zumdahl, Steven S. (2009). Chemical Principles 6th Ed. Houghton Mifflin Company. ISBN 0-618-94690-X. 
  3. ^ a b Sigma-Aldrich Co., Barium carbonate. Retrieved on 2014-05-06.
  4. ^ a b  One or more of the preceding sentences incorporates text from a publication now in the public domainChisholm, Hugh, ed. (1911). "Witherite". Encyclopædia Britannica 28 (11th ed.). Cambridge University Press. 
  5. ^ Withering, William (1784). "Experiments and Observations on Terra Poderosa". Philosophical Transactions of the Royal Society of London 74: 293–311. doi:10.1098/rstl.1784.0024. 
  6. ^ Whitelaw, G.P. (2003-10-25). "Standard Chrome Bath Control". finishing.com. Archived from the original on 13 December 2006. Retrieved 2006-11-29. 
  7. ^ Pradyot Patnaik. Handbook of Inorganic Chemicals. McGraw-Hill, 2002, ISBN 0-07-049439-8

External links[edit]


H2CO3 He
LiCO3 BeCO3 B C (NH4)2CO3,
NH4HCO3
O F Ne
Na2CO3,
NaHCO3,
Na3H(CO3)2
MgCO3,
Mg(HCO3)2
Al2(CO3)3 Si P S Cl Ar
K2CO3,
KHCO3
CaCO3,
Ca(HCO3)2
Sc Ti V Cr MnCO3 FeCO3 CoCO3 NiCO3 CuCO3 ZnCO3 Ga Ge As Se Br Kr
Rb2CO3 SrCO3 Y Zr Nb Mo Tc Ru Rh Pd Ag2CO3 CdCO3 In Sn Sb Te I Xe
Cs2CO3,
CsHCO3
BaCO3   Hf Ta W Re Os Ir Pt Au Hg Tl2CO3 PbCO3 (BiO)2CO3 Po At Rn
Fr Ra   Rf Db Sg Bh Hs Mt Ds Rg Cn Uut Fl Uup Lv Uus Uuo
La2(CO3)3 Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu
Ac Th Pa UO2CO3 Np Pu Am Cm Bk Cf Es Fm Md No Lr