13.2 Historical Background

The Natron Lakes in Egypt were a mystery. When dried out, the lakebeds were covered in a white

CaCO3 (s) + 2 NaCl (aq)              CaCl2 (aq)  +     Na2CO3 (s)

Berthollet in June 1799 was one of Napoleon’s most trust worthy scientist and advisors during the Egyptian campaign. He was charged by Napoleon to study the deposits at the shores at Natron Lake in Egypt. Berthollet presented a paper before the National Institute of Egypt.

Berthollet suggested a reason for the large sodium carbonate deposit Na2CO3 found at the shores of the Natron Lakes in Egypt. Sodium chloride NaCl solution was coming from nearby rivers which reacted with calcium carbonate CaCQ3 and large amount of sodium carbonate was produced at the shores at Natron Lakes. Chemical combinations (precipitations) are also influenced by the chemical equilibrium (chemical affinity) as well as by other principles.

Henry-Louis Le Chatelier was born in 1850. He graduated from Ecole des Mines in Paris 1873. After working in mining in industry, he returned to Ecole des Mines in Paris to work as a lecturer in it. Le Chatelier carried out some research on explosive materials and published his findings in the scientific research journals. Hi research had led studies led to the development of thermocouples from platinum with platinum rhodium electrode alloy.

Le Chatelier’s initial work on explosive and thermocouples had led to the study of thermodynamic. In 1884 he introduced the concept of chemical equilibrium to maintain stability of chemical reactions. He stated that “any system in stable chemical equilibrium, subjected to the influence of an external cause which tends to change either its temperature or its condensation (pressure, concentration, number of molecules in unit volume), either as a whole or in some of its parts, can only undergo such internal modifications as would, if produced alone, bring about a change of temperature or of condensation of opposite sign to that resulting from the external cause”.

[Reference:  https://www.britannica.com/biography/Henry-Louis-Le-Chatelier  ]

Henry Louis Le Chatelier Reference: https://en.wikipedia.org/wiki/Henry_Louis_Le_Chatelier