Sodium oxalate

• Disodium
• Oxalic acid disodium salt
• Oxalate of sodium

Colorless crystals

Fixed

2.34 g · cm -3

250 ° C ( decomposition)

• Moderately in water ( 37 g · l-1 at 20 ° C)
• Insoluble in ethanol and diethyl ether

Attention

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Sodium oxalate is a sodium salt of oxalic acid with the formula Na2C2O4. It belongs to the group of oxalate.

Properties

Sodium oxalate is a colorless free-flowing powder as salt, which does not affect hygroscopic and is only moderately soluble in water. It crystallizes in the monoclinic crystal system, space group P21 / a

At 290 ° C, the decomposition of sodium oxalate begins sodium carbonate and carbon monoxide.

The enthalpy of solution of sodium oxalate at 298.15 K is 13.86 kJ · mol -1.

In nature, sodium oxalate occurs as the rare mineral Natroxalat.

Production

Sodium oxalate may be obtained by the reaction of oxalic acid with sodium hydroxide.

Industrially, it is produced from sodium formate at a temperature of 360 ° C.

In addition, it is obtained in large quantities as waste material in the Bayer process (manufacture of aluminum hydroxide " alumina hydrate ").

Use

It can be used in conjunction with manganese (II ) sulfide for adjustment of potassium permanganate standard solutions ( volumetric standard ) (see also Manganometry ). Wherein the electro-deposition is a solution called sodium iron (III ) oxalate application, which is obtained, inter alia, sodium oxalate. Furthermore, it can be used as coloring agents (yellow / orange ) are used in pyrotechnics. In metallurgy it is used, for example, during the roasting of vanadium ore in the rotary kiln ( reacting vanadium pentoxide to sodium vanadate ). Other applications it is used as auxiliaries in the textile industry and as an ingredient for special cements.