Lead(II) oxalate is an organic compound with the formula PbC2O4. It is naturally found as a heavy white solid.[2]
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| Identifiers | |
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3D model (JSmol)
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| ChemSpider | |
| ECHA InfoCard | 100.011.284 |
| EC Number |
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PubChem CID
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| UNII | |
| UN number | 2291 |
CompTox Dashboard (EPA)
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| Properties | |
| PbC2O4 | |
| Molar mass | 295.219 |
| Appearance | White Powder |
| Density | 5.28 g/cm3 |
| Melting point | 327.4 °C (621.3 °F; 600.5 K) |
| Boiling point | 1,740 °C (3,160 °F; 2,010 K) |
| 0.0091 g/100 ml (25 °C) | |
| Thermochemistry | |
Std molar
entropy (S⦵298) |
146.0216 J [1] |
Std enthalpy of
formation (ΔfH⦵298) |
-851.444 kJ/mol |
| Hazards | |
| Occupational safety and health (OHS/OSH): | |
Main hazards
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Nephrotoxin, Reproductive Toxin, Neurotoxin, IARC Carcinogen, Birth Defects, Highly Toxic |
| GHS labelling: | |
  
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| Danger | |
| H302, H332, H360, H373, H410 | |
| P201, P202, P260, P261, P264, P270, P271, P273, P281, P301+P312, P304+P312, P304+P340, P308+P313, P312, P314, P330, P391, P405, P501 | |
| NIOSH (US health exposure limits): | |
PEL (Permissible)
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0.05 mg/m3, as Pb |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Preparation
editThis compound is commercially available. It may be prepared by the metathesis reaction between lead(II) nitrate and sodium oxalate:[3]
- Pb2+(aq) + C2O42− → PbC2O4 (s)
A dihydrate may be formed with water solutions. But the dihydrate dehydrates in air:[4]
- (PbC2O4•2H2O (s) → (PbC2O4 (s) + 2H2O (g)
The trihydrate (PbC2O4•3H2O) can be made by reacting a solution of lead(II) carbonate in perchloric acid with oxalylhydroxamic acid.[5]
Properties
editAs well as an anhydrous form, a monohydrate (PbC2O4•H2O),[5] a dihydrate (PbC2O4•2H2O) and a trihydrate (PbC2O4•3H2O) are known. The dihydrate is from the orthorhombic crystal system, with space group Pnam (number 62), with unit cell dimensions: a = 9.053 Å b = 8.036 Å and c = 7.834 Å. The unit cell volume is 569.8 Å3 with four formula per cell, giving a density of 3.860 g/cm3[4]
The trihydrate has triclinic crystals with space group P1 and unit cell dimensions and angles: a = 6.008 Å, b=6.671 Å, c=8.493 Å, α=74.70°, β=74.33°, and γ=80.98°. The unit cell volume is 314.41 Å3 with two formula per unit cell. Density is 3.69 g/cm3.[5]
Solubility
editLead(II) oxalate is insoluble in water. Its solubility is increased in presence of excess oxalate anions, due to the formation of the Pb(C2O4)22− complex ion.[6]
References
edit- ^ "Lead(II) Oxalate". Chemistry Reference. http://www.chemistry-reference.com/q_compounds.asp?CAS=814-93-7.
- ^ "Lead Oxalate". American Elements: The World's Manufacturer of Engineered & Advanced Materials http://www.americanelements.com/pboxl.html.
- ^ Grases, F.; Ruiz, J.; Costa-Bauzá, A. (1993). "Studies on Lead Oxalate Crystalline Growth". Journal of Colloid and Interface Science. 155 (2): 265–270. doi:10.1006/jcis.1993.1035.
- ^ a b Boldyreva, E. V.; Naumov, D. Y.; Podberezskaya, N. V.; Virovets, A. V. (15 November 1993). "Structure of lead(II) oxalate dihydrate". Acta Crystallographica Section C: Crystal Structure Communications. 49 (11): 1882–1884. doi:10.1107/S0108270193004652.
- ^ a b c Sheng-Hua, Huang; Ru-Ji, Wang; Mak, Thomas C. W. (April 1990). "Crystal structures of isomorphous cadmium(II) and lead(II) oxalate trihydrates". Journal of Crystallographic and Spectroscopic Research. 20 (2): 99–104. doi:10.1007/BF01160959.
- ^ Kolthoff, I.M.; Perlich, R. W.; Weiblen, D. (1942). "The Solubility of lead Sulfate and of Lead Oxalate in Various Media". Journal of Physical Chemistry. 46 (5): 561. doi:10.1021/j150419a004.