Chemistry
The Leblanc process was a batch process in which sodium chloride was subjected to a series of treatments, eventually producing sodium carbonate. In the first step, the sodium chloride was heated with sulfuric acid to produce sodium sulfate (called the salt cake) and hydrogen chloride gas according to the chemical equation
- 2 NaCl + H2SO4 → Na2SO4 + 2 HCl
This chemical reaction had been discovered in 1772 by the Swedish chemist Carl Wilhelm Scheele. Leblanc's contribution was the second step, in which the salt cake was mixed with crushed limestone (calcium carbonate) and coal and fired. This reaction happens in two parts. First the coal (carbon) was oxidized to carbon dioxide, reducing the sulfate to sulfide. Second, the calcium and sodium swap their ligands to leave the thermodynamically favorable combination of sodium carbonate and calcium sulfide. This mixture is called black ash.
- Na2SO4 + 2 C → Na2S + 2 CO2
- Na2S + CaCO3 → Na2CO3 + CaS
The soda ash was then separated from the black ash by washing it with water. The wash water was then evaporated to yield solid sodium carbonate. This extraction process was termed lixiviation.
Read more about this topic: Leblanc Process
Famous quotes containing the word chemistry:
“Science with its retorts would have put me to sleep; it was the opportunity to be ignorant that I improved. It suggested to me that there was something to be seen if one had eyes. It made a believer of me more than before. I believed that the woods were not tenantless, but choke-full of honest spirits as good as myself any day,—not an empty chamber, in which chemistry was left to work alone, but an inhabited house,—and for a few moments I enjoyed fellowship with them.”
—Henry David Thoreau (1817–1862)
“For me chemistry represented an indefinite cloud of future potentialities which enveloped my life to come in black volutes torn by fiery flashes, like those which had hidden Mount Sinai. Like Moses, from that cloud I expected my law, the principle of order in me, around me, and in the world.... I would watch the buds swell in spring, the mica glint in the granite, my own hands, and I would say to myself: “I will understand this, too, I will understand everything.””
—Primo Levi (1919–1987)
“...some sort of false logic has crept into our schools, for the people whom I have seen doing housework or cooking know nothing of botany or chemistry, and the people who know botany and chemistry do not cook or sweep. The conclusion seems to be, if one knows chemistry she must not cook or do housework.”
—Ellen Henrietta Swallow Richards (1842–1911)