Lavoisier, Proust,
Berthollet, and the Laws
of Conservation of Mass
and Definite Proportions
Madeleine Scriber
And
Sydney Tress
Antoine Lavoisier
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August 26, 1743- May 8, 1794
Born in Paris, France
Studied at College des Quatre Nations
Attended College Mazarin
Colleague: Guillaume-Francois Rouelle
Won a prize on lighting the streets of Paris
Designed a new method for preparing
saltpeter.
Studied the nature of combustion and
devised a system of naming elements
Lavoisier Biography
“Father of Modern Chemistry”
 He published a documentary, Traité
Elémentaire de Chimie
 Denied the existence of Phlogiston
 Establishment of the Law of Conservation
of Mass
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Lavoisier Biography Continued
Replica of Lavoisier's
calorimeter, a piece of
equipment for measuring
the amount of heat
produced by combustion
Used to investigate
combustion. Lavoisier
called the gas oxygen
Replica of apparatus for
hydrogen combustion
experiment, made from
a sketch by Madame
Lavoisier
Lavoisier Lab Apparatus
They proposed new names for elements.
The need for an international
nomenclature consistently reflecting the
composition of substances became aware
to Lavoisier.
 Before Lavoisier the language used in
chemical texts was full of inconsistencies,
imprecision and double meanings.
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Lavoisier and Berthollet
Joseph Proust
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September 26, 1754- July 5, 1826
Born in Angers, France
Taught Chemistry School at Sergovia and
the University of Salamanca in Spain
Chemical analysts
Discovered that each pure compound has
its own characteristic elemental
composition.
He put hydrogen into the realm of science
was disproving Berthollet with the law of
definite proportions
Proust Biography
first accumulated conclusive evidence for
it in a series of researches on the
composition of many substances,
especially the oxides of iron
 Law of Constant Proportions: known for
helping prove the idea that every pure
chemical compound consists of elements
in a definite proportion
 Rival: Berthollet
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Proust Biography Continued
Claude Louis Berthollet
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December 9, 1748- November 6, 1822
Born in Talloires, France
Started his studies at Chambéry and then
in Turin where he graduated in medicine.
Active participant of the Academy of
Science in 1780
Rival: Proust
He first produced a modern bleaching
liquid in 1789 in his laboratory in Paris,
France, by passing chlorine gas through a
solution of sodium carbonate.
Berthollet Biography
Known for his scientific contributions to
theory of chemical equilibrium.
• First to demonstrate the bleaching action
of chlorine gas.
• First determined the elemental
composition of ammonia.
• First proved that chemical reactions and
affinities are dependent upon physical
factors, such as mass and temperature.
•
Berthollet Biography
Continued
Burette, a common
laboratory apparatus for
carrying out titration, an
important experimental
technique in equilibrium and
analytical chemistry.
Berthollet Lab Apparatus
• Stated that in a chemical reaction,
matter is neither created or destroyed
• It brought to the end the
misconception of the existence of
Phlogiston.
• An entire class of substances does not
follow this rule. The compounds are
called non-stiochiometric compounds.
• also named berthollides in his honor.
Laws of Conservation of Mass
and Definite Proportions

"Antoine Lavoisier." Antoine Lavoisier. N.p., n.d. Web. 23 Oct.
2013.
<http://www.historylearningsite.co.uk/antoine_lavoisier.htm>.
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"Joseph Proust." Joseph Proust. N.p., n.d. Web. 24 Oct. 2013.
<http://www.vzhang.com/vzfiles/joseph_proust.htm>.
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"Claude-Louis Berthollet (French Chemist)." Encyclopedia
Britannica Online. Encyclopedia Britannica, n.d. Web. 24 Oct.
2013.
<http://www.britannica.com/EBchecked/topic/62812/ClaudeLouis-Berthollet>.
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Dingrando, Laurel. "Law of Definite Proportions." Chemistry:
Matter and Change. New York, NY: Glencoe/McGraw-Hill, 2005.
75. Print.
Bibliography