Oxalic acid, preparation, properties, chemical reactions

Oxalic acid, preparation, properties, and chemical reactions.

 

 

Oxalic acid (also entandikwa acid) – an organic substance belonging to the limit dibasic carboxylic acids.

 

Oxalic acid, formula, specifications, characteristics

Physical properties of oxalic acid

Chemical properties of oxalic acid

Obtaining oxalic acid

Safety when handling oxalic acid. The Requirements Of GOST

The use of oxalic acid

 


Oxalic acid, formula, features:

Oxalic acid (also entandikwa acid) – an organic substance belonging to the limit dibasic carboxylic acids.

Chemical formula of oxalic acid C2H2O4. The rational formula of oxalic acid HOOC−COOH, or (COOH)2. Isomers has not.

The structure of the molecule of oxalic acid:

 

Oxalic acid (entandikwa acid) is the simplest dibasic acid, the first member of the homologous series of dibasic carboxylic acids limit.

Is a strong organic acid.

Oxalic acid appearance is a colorless crystals. Has two crystalline modifications: α – orthorhombic bipyramidal (density 1,900 g/cm3), β – monoclinic prismatic (density 1,895 g/cm3).

Oxalic acid is a combustible substance. The ignition temperature of the layer 518 °C. For dust-air mixture from the lower concentration limit of ignition – 205 g/cm3.

Soluble in water, partially in diethyl and ethyl alcohol, insoluble in benzene, chloroform, petroleum ether

Oxalic acid received its name from the fact that oxalate is formed during the fermentation. Was first obtained in 1824 by the German chemist Friedrich Wohler from Tiziana and water.

In nature, oxalic acid contains in sorrel, rhubarb, and sorrel, the cannon and some other plants, and in raw vegetables in free form and in the form of oxalates of potassium and calcium.

Salts and esters of oxalic acid are termed oxalates.

Name oxalic acid in English – oxalic acid.

Oxalic acid has toxic effect dangerous to life and health (risk depends on the concentration), has corrosive properties.

 

Physical properties of oxalic acid:

Parameter name: Value:
Color without color
The smell odorless
Taste sour
Aggregate state (at 25 °C and atmospheric pressure of 1 ATM.) colorless crystals
The density of the orthorhombic bipyramidal crystal modification (at 25 °C and atmospheric pressure of 1 ATM.) g/cm3 1,9
The density of the orthorhombic bipyramidal crystal modification (at 25 °C and atmospheric pressure of 1 ATM.) kg/m3 1900
The density of monoclinic prismatic crystal modification (at 25 °C and atmospheric pressure of 1 ATM.) g/cm3 1,895
The density of monoclinic prismatic crystal modification (at 25 °C and atmospheric pressure of 1 ATM.) kg/m3 1895
Melting point, °C 189,5
The auto-ignition temperature, °C 518
The dissociation constant of the acid 1,25; 4,14
Specific heat of combustion, MJ/kg 2,79
Molar mass, g/mol 90,04

 

Chemical properties of oxalic acid:

Oxalic acid is a strong organic acid and acid manifests properties characteristic of the carboxylic acids.

It is characterized by the following chemical reactions:

1. the decomposition reaction of oxalic acid when heated:

C2H2O4 → CO + CO2 + H2O (to, kat = H2SO4 (conc.)).

When heated with concentrated sulphuric acid decomposes into carbon monoxide (carbon monoxide), carbon dioxide and water.

2. the reaction of oxalic acid c potassium chlorate:

C2H2O4 + 2KClO3 → K2CO3 + 2ClO2 + CO2 + H2O.

Oxalic acid reacts with potassium chlorate. The reaction formed potassium carbonate, chlorine dioxide, carbon dioxide and water.

This reaction is used for laboratory synthesis of chlorine dioxide.

3. the reaction of oxalic acid c ammonia solution:

C2H2O4 + 2NH3 → (NH4)2C2O4.

Oxalic acid reacts with ammonia dissolved in water. The reaction produces ammonium oxalate.

4. the reaction of oxalic acid c with iodine:

C2H2O4 + I2 → 2HI + 2CO2.

Oxalic acid reacts with iodine. The reaction produced yodovidona and carbon dioxide.

A similar reaction comes from chlorine.

These reactions are used to produce yodovidona and hydrogen chloride.

5. the reaction of oxalic acid c potassium carbonate (or sodium carbonate):

K2CO3 + H2C2O4 → K2C2O4 + CO2 + H2O

Na2CO3 + H2C2O4 → Na2C2O4 + CO2 + H2O.

Oxalic acid reacts with the carbonate of potassium (or carbonate of sodium). In the reaction, the formed oxalate of potassium (or oxalate sodium), carbon dioxide and water.

Similar reactions are derived carbonate lithiumcarbonate rubidium carbonate, and cesium.

6. reaction of the dissociation of oxalic acid in aqueous solution:

H2C2O4 ↔ 2H+ + C2O42-.

In an aqueous solution of oxalic acid dissociates into ions.

 

Obtaining oxalic acid:

Oxalic acid is obtained:

the oxidation of carbohydrates, alcohols and glycols with a mixture of nitric and sulphuric acids in the presence of vanadium oxide (V2O5);

– oxidation of ethylene and acetylene with nitric acid in the presence of chloride of palladium (PdCl2) nitrate or palladium (Pd(NO3)2);

– oxidation of propylene to liquid nitrogen oxide (NO2);

– of sodium formate.

 

Safety when handling oxalic acid. Requirements GOST:

Oxalic acid is a strong organic acid, in large quantities may cause irritation of the mucous membranes of the esophagus, stomach, intestines, respiratory system and skin.

The maximum permissible concentration of oxalic acid in water of water objects of drinking and cultural-domestic absopositively – 0,5 mg/dm3., limiting indicator of harm – obschesanitarnyh. (see GOST 22180-76 Reagents. Oxalic acid. Specifications (with Amendments No. 1, 2)).

When working with oxalic acid should be used personal protective equipment (respirators type “Petal” according to GOST 12.4.028, goggles according to GOST 12.4.013, rubber gloves according to GOST 20010), and to observe the rules of personal hygiene.

The premises where work is being carried out with the drug, must be equipped with continuously operating ventilation system. Analysis of the preparation should be conducted in a fume hood laboratory.

Oxalic acid is a combustible substance. The ignition temperature of the layer 518 °C. For dust-air mixture from the lower concentration limit of ignition – 205 g/cm3. Fire extinguishing agents are atomized water, chemical and mechanical foam.

 

The application of oxalic acid:

Oxalic acid is used:

– in the textile and leather industries as a mordant when dyeing silk and wool,

– in metallurgy for cleaning metals from rust, oxides, scale, rust,

– in beekeeping for the treatment of bees,

– in the household as a means for removal of rust, detergents, bleaches and disinfectants,

in medicine and pharmacology

in analytical and organic chemistry as a reagent to precipitate the rare earth elements.

 

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