what is sodium carbonate used for
1 Soda ash (Na2CO3) , or sodium carbonate, is used in the manufacture of glass, paper, rayon, soaps, and detergents. 2  It is also used as a water softener, since carbonate can precipitate the calcium and magnesium ions present in hard water.Soda ash is also used to control pH (carbonate solutions neutralize acids, producing only carbon dioxide and water).t is also used as a water softener, since carbonate can precipitate the calcium and magnesium ions present in hard water. Soda ash is also used to control pH (carbonate solutions neutralize acids, producing only carbon dioxide and water).