Soda ash has a tendency to absorb moisture from the atmosphere. The 
			moist soda ash then starts absorbing atmospheric carbon dioxide. 
			This phenomenon of absorption of moisture and carbon dioxide by soda 
			ash is known as weathering. After weathering, soda ash is likely to 
			contain appreciable moisture and sodium bicarbonate, but the total 
			alkali content of the bag does not change. Soda ash has a tendency 
			to cake when it comes in contact with moisture and, consequently, 
			becomes lumpy.
			
			Chemical formula : Na2CO3
			
				
					
						| 
						
						Characteristics | 
						
						IS 251 : 1998 specifications
 | 
						
						TCL-assured specifications | 
						
						Units | 
					
						| 
						Molecular weight | 
						  | 
						106 | 
						  | 
					
						| 
						Bulk density | 
						500 – 750 | 
						550 – 720 | 
						Kg/m3 | 
					
						| 
						Volatile matter content(at the time of packing)
 | 
						2 | 
						0.80 | 
						%, max | 
					
						| 
						Total alkalinity (as Na2CO3) | 
						98.5 | 
						99.0 | 
						%, min | 
					
						| 
						Sulphates (as Na2SO4) | 
						0.08 | 
						0.03 | 
						%, max | 
					
						| 
						Chlorides (as NaCl) | 
						1.0 | 
						0.80 | 
						%, max | 
					
						| 
						Iron(as Fe2O3)
 | 
						By colorimetric method | 
						  | 
						0.0029 | 
						%, max | 
					
						| 
						By spectrophotometric method | 
						0.007 | 
						0.002 | 
					
						| 
						Matter insoluble in water | 
						0.15 | 
						0.03 | 
						%, max | 
				
				
				Light soda ash is one of the most important 
				basic industrial chemicals. Light soda ash is used to regulate 
				pH in many chemical process streams. The superior buffering 
				capacity of soda ash versus caustic soda offers advantages in 
				adjusting plant wastewater pH ranges.
				
				Soda ash is used as the sodium source for 
				sodium sulfite/bi-sulfite pulping liquors used in the sulfite, 
				CMP, and CTMP processes, and in NSSC pulping.
				
				It is also possible to replace a portion of 
				the caustic soda in many pulp bleaching applications such as 
				caustic extraction or hydrogen peroxide bleaching of mechanical 
				or chemical pulps. However, the higher pH requirements of these 
				applications may necessitate the continued use of some caustic 
				soda.
				
				It is also possible to replace a portion of 
				the caustic soda in many pulp bleaching applications such as 
				caustic extraction or hydrogen peroxide bleaching of mechanical 
				or chemical pulps. However, the higher pH requirements of these 
				applications may necessitate the continued use of some caustic 
				soda.
				
				In addition, it is the most widely used 
				fixed alkali for the manufacture of other alkali products, 
				sodium salts, glass, soap, sodium silicates, detergent, 
				bicarbonates, bichromates, cellulose and rayon, iron and steel, 
				aluminum, cleaning compounds, textiles and dyestuffs, drugs and 
				many other materials. It is also used as an alkali for household 
				purposes and as washing powder by laundries.