Henri Louis Le Chatelier

French chemist

• Born: October 8, 1850; Paris, France
• Died: September 17, 1936; Miribel-les-Échelles, France

Nineteenth-century French chemist Henri Louis Le Chatelier discovered the response of a chemical equilibrium to outside disturbances, and Le Chatelier’s principle was subsequently named in his honor. His principle has become important to the chemical industry for developing efficient chemical processes. Le Chatelier also contributed to knowledge in metallurgy and cement compounds.

Primary field: Chemistry

Specialties: Analytical chemistry; inorganic chemistry; thermodynamics

Early Life

Henri Louis Le Chatelier was born in Paris on October 8, 1850. His father, Louis Le Chatelier, was a mining engineer who played a key role in construction of the railroad network in France, Spain, and Austria; he also contributed to French industrialization in the fields of aluminum production and steel making. Henri’s mother, Louise Madeleine Elisabeth Durand, came from a family of architects. She was a devout Catholic and stressed discipline in child rearing. Henri was the oldest of six children and had one sister and four brothers.

Le Chatelier attended the Collège Rollin in Paris, receiving undergraduate degrees in 1867 and 1868. In 1869, he enrolled at the École Polytechnique, a Paris engineering school and his father’s alma mater. He then served as second lieutenant in the French army from 1870 to 1871 during the Franco-Prussian War and afterward enrolled in France’s national mining engineering school, École des Mines. Le Chatelier received a degree in mine engineering in 1875.

Le Chatelier’s first assignment was to participate in an engineering mission to the French colony of Algeria in Africa. In the fall of 1875, he accepted an administrative position as mining engineer in the French town of Bescançon. His first scientific paper, published in 1876, looked at a new method to isolate impurities in wrought iron.

In 1876, Henri married Geneviève Nicolas, who was the youngest daughter of a friend of his father, as well as the sister of fellow students at École Polytechnique. Henri and Geneviève had seven children, five of whom eventually worked in scientific fields.

Life’s Work

In 1877, based on the strength of his previous work in chemistry as a student at the school, Le Chatelier was offered the position of Chair of General Chemistry at the École des Mines. As professor, Le Chatelier believed strongly that scientific research should be built on experiments. He rejected purely verbal explanations or purely mathematical considerations, especially when calculations and theories stood at odds with experimental results.

In 1878, Le Chatelier and a colleague, Ernest-François Mallard, were asked to research ways to prevent mine explosions, which were often caused by firedamp, any of a number of combustible gases such as methane that can ignite at critical concentrations. Le Chatelier conducted experiments to determine the temperature at which firedamp could ignite and the speed at which flames spread in mixed-gas atmospheres, which then led him to determine the specific heat and flame temperatures of gases at high temperatures. The two men also improved upon the current flame test for the detection of firedamp and simplified the method for estimating the amount of firedamp in a mine atmosphere. Le Chatelier was then able to construct a method by which conditions for the safe use of explosives in mines could be determined. In 1882, Le Chatelier combined this research with his ongoing study of cement and plaster (the subject of his doctoral dissertation), and in 1884, he made the most significant discovery of his scientific career.

Experimenting with cement included the dissociation of calcium carbonate into calcium oxide and carbon dioxide in a chemical equilibrium reaction. In a short article published in 1884, Le Chatelier referred to his discovery that a system that is in chemical equilibrium will always act to lessen or eliminate the effect of a specific change by seeking to reestablish a thermodynamic equilibrium as close to the original state as possible. In other words, systems that are in chemical equilibrium will always counteract the changes that are introduced into the system in order to return to equilibrium. This was later called Le Chatelier’s principle.

Le Chatelier was awarded his PhD in 1887. His dissertation summarized analysis of the binding power of various types of cement. Also that year, Le Chatelier switched his university appointment to become Chair of Industrial Chemistry at the École des Mines and was made a knight in France’s Légion d’Honneur (Legion of Honor).

Le Chatelier eventually returned to a focus in metallurgy, and in 1893, he founded the Committee on Alloys at the French Société d’Encouragement pour l’Industrie Nationale (Society for the Encouragement of National Industry). Around 1895, a discussion with fellow French scientist Floris Osmond, one of the founders of metallography, led Le Chatelier to examine alloys under the microscope. He experimented with heating and cooling solid alloys and discovered transformations in their physical properties and chemical composition that occurred during the experimental processes. To better measure the high temperatures involved, Le Chatelier designed a thermoelectric couple, or thermocouple, of platinum and rhodium in 1896. He published a summary of his results in metallurgy in 1897.

In addition to his professorship at École des Mines, Le Chatelier became a professor of mineral chemistry in 1898 at the Collége de France, where he offered a series of free public lectures to other scientists, teachers, and professors. Le Chatelier presented ten different lecture series from 1898 to 1907, with topics including chemical thermodynamics, metallurgy, analytical chemistry, and the fundamental principles of chemistry.

By 1900, Le Chatelier was investigating ammonia synthesis, and in 1901, he designed an experiment in which he injected a mix of compressed nitrogen and hydrogen into a steel container called a Berthelot bomb. The mixture was then heated via a platinum spiral. Suddenly, a gigantic explosion destroyed the apparatus and severely injured a laboratory assistant. Le Chatelier identified the presence of regular air in the steel container as the cause of the explosion, and the disaster discouraged him from further research into ammonia synthesis.

In 1904, Le Chatelier founded the Revue de Métallurgie (Journal of metallurgy) and would serve as the editor in chief until 1920. In 1907, he was elected to France’s Académie des Sciences (Academy of Sciences) and to the Royal Swedish Academy of Sciences. That same year he also began giving lectures at the Sorbonne in Paris.

Le Chatelier became a member of Great Britain’s Royal Society in 1913 and received its Davy Medal in 1916. When World War I began in 1914, he continued to teach, but his research focused on topics that would directly benefit France in the war, such as metallurgical studies of heat treatment of shell casings, which in turn improved their design and efficacy. Le Chatelier retired from teaching in 1919.

Le Chatelier remained involved in the scientific community through membership in professional associations, and he also became interested in applying scientific methods to industrial organization. In 1928, he published a French edition of American mechanical engineer F. W. Taylor’s The Principles of Scientific Management (1911).

Henri Le Chatelier died at his vacation home at Miribel-les-Échelles on September 17, 1936.

Impact

Le Chatelier’s principle, that a chemical equilibrium always seeks to stabilize itself, allowed chemists to have direct control over chemical processes, which proved to have far reaching applications within the chemical industry by allowing scientists to maximize the efficiency of chemical processes and improving their ability to obtain desired products from chemical reactions.

Le Chatelier was instrumental in promoting the close relationship between basic research and industrial applications, and his constant search for ways to apply his research led to the industrial use of many of his discoveries and inventions. In construction, for example, a machine called the Le Chatelier test device, which tests the heat expansion of cement mortar samples and materials, was still in use through the first decade of the twenty-first century.

As a dedicated professor who lectured at three of France’s prime academic institutions, Le Chatelier made a tremendous impact on the education and subsequent research of generations of future chemists and metallurgists. Furthermore, Le Chatelier’s emphasis on experiments made him skeptical of pure theory, and this focus served as an important reminder of the need for experimental verification, a trademark of modern-day science.

Bibliography

Côme, Guy-Marie. Gas-Phase Chemical Reactions: Chemical Engineering Kinetics. Reprint. New York: Springer, 2010. Print. Le Chatelier’s principle is presented; its applications regarding the effect of temperature and pressure changes on a chemical equilibrium are discussed through practical examples.

Oriakhi, Christopher O. Chemistry in Quantitative Language: Fundamentals of General Chemistry Calculations. New York: Oxford UP, 2009. Print. Directed toward students in general chemistry courses, with material introducing and discussing applications of Le Chatelier’s principle, the common-ion effect, an application of the principle, and complex ion-equilibria and formation of complex ions as based on Le Chatelier’s principle.

Thompson, Robert Bruce. Illustrated Guide to Home Chemistry Experiments. Sebastopol, CA: Maker, 2008. Print. Three practical experiments are presented to observe the results determined by Le Chatelier’s principle.