Why is sodium carbonate a strong base

sodium
Sodium carbonate decahydrate
Sodium carbonate
Sodium carbonate decahydrate
105.989 g / mol
286.142 g / mol

not specified
2.54 g / cm3
1.46 g / cm3
+856 ° C
100g H2O dissolve 21.4 g (L) (anhydrous)
100g H2O dissolve 21.66 g (L) (decahydrate)


Anhydrous
White dust

Decahydrate
Crystalline powder



properties
Sodium carbonate anhydrous is a white powder that is irritating to the skin and mucous membranes. It is very hygroscopic and absorbs moisture from the air. When heated to 40 ° C, the solubility of the anhydrous sodium carbonate initially increases, but then decreases again slightly with further heating:


Water solubility (L): 100g H.2O solve x g sodium carbonate anhydrous

0 ° C
20 ° C
40 ° C
60 ° C
80 ° C
100 ° C
7.1 g
21.4 g
48.5 g
46.5 g
45.8 g
45.5 g


When dissolving in water, a strongly alkaline solution is formed with the development of heat. The carbonate ion reacts as a base with a water molecule to form a hydrogen carbonate ion and a hydroxide ion:

CO32− + H2O HCO3 + OH  



A moistened universal indicator paper turns blue with sodium carbonate.

With a strong acid, sodium carbonate develops the gas carbon dioxide and the corresponding salts of the acid with effervescence. With hydrochloric acid, sodium chloride, carbon dioxide and water are formed. With sulfuric acid you get sodium sulfate, carbon dioxide and water:

N / A2CO3 + 2 HCl 2 NaCl + H2O + CO2
N / A2CO3 + H2SO4  N / A2SO4 + H2O + CO2



Diluted hydrochloric acid reacts with sodium carbonate with foaming.

Several hydrates of sodium carbonate are known. When the decahydrate is heated, it changes to the monohydrate above 34 ° C. If the heating is continued, the form free of water of crystallization is obtained from 107 ° C. The anhydrous form is also known as calcined soda. It occurs naturally in the mineral natrite. The monohydrate forms the mineral thermonatrite, the decahydrate the mineral soda. The origin of the historical name soda for sodium carbonate decahydrate has not been clearly established. It may be referring to the Arabic word suwwâd ("Salt Plant Ash") back.

Anhydrous: Na2CO3
Monohydrate: Na2CO3 • H2O
Heptahydrate: Well2CO3 • 7 H.2O
Decahydrate: Well2CO3 • 10 H.2O


Manufacturing
use
Sodium carbonate is used extensively by the glass industry: the addition prevents the melt from crystallizing out when the glass melts solidify. This results in amorphous, very homogeneous and transparent glass. The concentration also determines the flowability of the melt. In the chemical industry, sodium carbonate is an important intermediate product for other sodium compounds, for example for the production of sodium hydroxide, sodium hydrogen carbonate or ultramarine blue. The pulp and paper industry uses the carbonate for digestion, neutralization, cleaning, bleaching and processing of waste paper. In iron smelting, it is used in the desulphurisation of pig iron and steel and as a flotation and fluxing agent. It is also used to soften water, anhydrous sodium carbonate is also suitable as a drying agent for rooms. The shiny surface of the lye pastry is achieved by treating it with soda. Other uses can be found in the leather, ceramic and textile industries.



Sodium carbonate is still used today in detergent production. In 1878 "Henkel's bleaching soda" came on the market, a mixture of soda and sodium silicate in a ratio of 4 to 1. It was used to make a washing solution and to soften the water. Today's detergents contain surfactants that no longer have such a high pH value and are more gentle on the textile fabric.


Further information
Information on carbon dioxide and carbonates
Information about detergents
Research assignment: Unknown substance