Quite interesting: Sodium bicarbonate

I suspect some people are reading that title thinking “really?” But the fact of the matter is that the synthesis of sodium bicarbonate was the first triumph of industrial chemistry and therefore the first entry of the private sector into the chemical arena, something that still sets chemistry apart from the other major academic sciences, biology and physics; this is one of the reasons that chemistry is so advanced today.

But why sodium bicarbonate, is it really that important? The obvious answer is yes, but for things that we all now take for granted; soap and white cotton shirts. If this still sounds weird the industrial synthesis of sodium bicaronbate was described in 1856 as “one of the great benefits, if not the greatest that modern science has bestowed on humanity” but why?

Back in the 18^th century there was a massive demand for “washing soda” to bleach the cotton cloth that was being produced in huge quantities from the emerging mills in France and Britain (the cotton initially comes out of the looms grey). Soaking cotton in alkali produced a pure white fabric which could be sold or dyed to other colours very easily however, demand was increasingly outstripping supply.

The only source came from local farmers who spent whole months of the year (during which they would not farm) collecting seaweed, or grasses in the dunes to burn and then selling the resulting alkali powder. Being able to synthesise washing soda would allow more food to be produced for the growing population and allow the cotton industry to continue to expand.

Nicolas Leblanc worked out the first synthesis to obtain synthetic sodium bicarbonate via a rather terrifying method using boiling sulfuric acid to convert sodium chloride to sodium sulfate with HCl gas as a by-product. Sodium sulfate is then able to be converted to the carbonate by reaction with calcium carbonate and carbon (in the form of charcoal):

What’s this got to with soap? Well soap is formed by boiling fat in alkali solution so cheap access to sodium bicarbonate meant that not only did you get cheap cotton clothing, but also cheap soap. Making soap (and therefore washing with it) available to almost everyone with had frankly unimagined health benefits (certainly by Leblanc who ended up killing himself in 1806). So despite being invented for the cotton industry, the industrial sodium bicarbonate synthesis hugely improved the hygiene of vast numbers of people in Europe and America and therefore saved lives in the most literal sense  

Troublingly however, the Leblanc process also caused the first chemical pollution crisis. The HCl gas produced caused huge problems in countryside surrounding the factories (not to mention the horrors it inflicted on the employees inside!) and led to some of the first controls on factories for public health benefits and ultimately led to the development of safer and more efficient processes.

Swings and roundabouts then, but still much more interesting than you expect of one of the simplest compounds in a chemists tool kit.