Sodium bicarbonate hydrogencarbonate

In many countries, sodium carbonate (soda ash) and sodium hydrogencarbonate (commonly called sodium bicarbonate) are manufactured by the Solvay process (Figure... 

The success of the Solvay process lay in the efficient use of the ammonia obtained as a by-product in the coke industry. The key step involves the reaction of ammonia gas and carbon dioxide gas in a saturated sodium chloride solution. That results in the formation of sodium hydrogencarbonate (bicarbonate) NaHCOj and ammonium chloride. The sodium bicarbonate precipitate is filtered from the solution, dried and heated to form sodium carbonate. Carbon dioxide is obtained by heating limestone CaCOj in a lime kiln. One noteworthy feature of the Solvay process is the effective use and recycling of materials. The only ultimate by-product is calcium chloride Ca-CI2, for which the demand is limited. To some extent it is used for deicing roads in winter and for dust control on dirt roads in the summer. 

---