Sodium oxalate
Structural formula | ||||||||||||||||
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General | ||||||||||||||||
Surname | Sodium oxalate | |||||||||||||||
other names |
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Molecular formula | Na 2 C 2 O 4 | |||||||||||||||
Brief description |
colorless and odorless crystals |
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properties | ||||||||||||||||
Molar mass | 134.01 g mol −1 | |||||||||||||||
Physical state |
firmly |
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density |
2.27 g cm −3 |
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Melting point |
250 ° C (decomposition) |
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solubility |
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As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions . |
Sodium oxalate is a sodium salt of oxalic acid with the empirical formula Na 2 C 2 O 4 . It belongs to the group of oxalates .
Production and occurrence
Sodium oxalate can be obtained by reacting oxalic acid with sodium hydroxide solution .
It is produced on an industrial scale from sodium formate at a temperature of 360 ° C.
It is also produced in large quantities as waste in the Bayer process (production of aluminum hydroxide "alumina hydrate").
In nature, sodium oxalate occurs as the very rare mineral natroxalate .
properties
Sodium oxalate is a colorless, powdery, free-flowing salt that does not have a hygroscopic effect and only dissolves moderately in water. It crystallizes in the monoclinic crystal system in the space group P 2 1 / a (space group no. 14, position 3) .
At 290 ° C, sodium oxalate begins to decompose into sodium carbonate and carbon monoxide .
The enthalpy of solution of sodium oxalate at 298.15 K is 13.86 kJ mol −1 .
use
It can be used in conjunction with manganese (II) sulphide to adjust potassium permanganate standard solutions ( Urtitersubstanz according to Sörensen ) (see also manganometry ). When plating a solution called sodium iron (III) oxalate is application which is obtained inter alia from sodium oxalate. It can also be used as a color generator (yellow / orange) in pyrotechnics . In metallurgy it is used for. B. in the roasting of vanadium ores in a rotary kiln (conversion of vanadium (V) oxide to sodium metavanadate ). It is also used as an aid in the textile industry and as an ingredient in special cements.
Individual evidence
- ↑ a b c d e f Entry on sodium oxalate in the GESTIS substance database of the IFA , accessed on January 8, 2018(JavaScript required) .
- ↑ a b Entry on sodium oxalate. In: Römpp Online . Georg Thieme Verlag, accessed on September 29, 2014.
- ↑ J. Lowe, M. Ogden, A. McKinnon, G. Parkinson: Crystal growth of sodium oxalate from aqueous solution . In: Journal of Crystal Growth 2002 , 237 - 239 , pp 408-413. doi : 10.1016 / S0022-0248 (01) 01864-4 .
- ^ T. Yoshimori, Y. Asano, Y. Toriumi and T. Shiota: Investigation on the drying and decomposition of sodium oxalate . In: Talanta 1978 , 25 (10), pp. 603-605. doi : 10.1016 / 0039-9140 (78) 80158-1 .
- ↑ MZH Rozaini, P. Brimblecombe: The solubility measurements of sodium dicarboxylate salts; sodium oxalate, malonate, succinate, glutarate, adipate and in water from T = (279.15 to 358.15) K . In: The Journal of Chemical Thermodynamics 2009 , 41 (9), pp. 980-983. doi : 10.1016 / j.jct.2009.03.017 .