What is the more common name for sodium carbonate
Sodium carbonate to approximately or to yield pure sodium carbonate similar to last step of the Solvay process. More sodium chloride is added to the remaining solution of ammonium and sodium chlorides; also, more ammonia is pumped at 30-40 °C to this solution. The solution temperature is then lowered to below 10 °C. Solubility of ammonium chloride is higher than that of sodium chloride at 30 °C and lower at 10 °C. Due to this temperature-dependent solubility difference and the common-ion effect, ammonium chloride is precipitated in a sodium chloride solution. The Chinese name of Hou's process, "lianhe zhijian fa" (), means
Sodium carbonate ammonia (NH) buffers the solution at a basic pH; without the ammonia, a hydrochloric acid byproduct would render the solution acidic, and arrest the precipitation. The necessary ammonia "catalyst" for reaction (I) is reclaimed in a later step, and relatively little ammonia is consumed. The carbon dioxide required for reaction (I) is produced by heating ("calcination") of the limestone at 950 - 1100 °C. The calcium carbonate (CaCO) in the limestone is partially converted to quicklime (calcium oxide (CaO)) and carbon dioxide: The sodium bicarbonate (NaHCO) that precipitates out in reaction (I) is filtered out from the hot ammonium chloride