By Sean Alfonso and Andrew Kelly

1. Lavoisier, Proust and Berthollet and the Laws of Conservation of Matter and Definite Proportions By Sean Alfonso and Andrew Kelly

2. Antoine Lavoisier • Born 26 of August 1743 and Executed 8 May 1794 • He entered Le College Mazarin when he was 11 • During his last 2 years at the college he grew interested in science (astronomy, chemistry' botany) • He graduated with a degree in law but pursued scientific research on the side • When he was 26 he was elected to the Academy of Sciences where he helped develop the metric system • He also was a member of the FermeGenerale which was in charge of taxation of French Commoners.

3. Lavoisier’s Scientific Contribution • Lavoisier is considered "the Father of Modern Chemistry" and created the Law of Conservation of matter and The law of definite Proportions • His rival was Joseph Priestly and phlogiston theory which proposed a fire-like element called phlogiston, contained within combustible bodies. • Phlogiston theory also claimed that weight and thus mass was affected by temperature. • Lavoisier made a number of experiments, all done in closed vessels, where total weight remained constant. • In the end he disproved phlogiston theory. • Although he was not the first to test the conservation of mass but he is credited for its discovery.

4. Joseph Proust • Born September 26 1754 in Angers France, Died July 5 1824 in Angers France • Was taught chemistry by his father who was the town Apothecary • Under Carlos IV's influence Proust went to Spain. There he taught at the Chemistry School in Segovia and at the University of Salamanca. But was forced to move back to France when Napoleon invaded Spain.

5. Proust’s Scientific Contribution • He proved that the relative quantities of any given pure chemical compound’s constituent element remains invariant, regardless of the compounds source. • In basic terms: A compound’s elemental composition always remains the same, no matter the source. • This became known as the law of definite proportions, this disapproved Berthollet’s theory. • He did this by studying copper sulfate and when he recreated it, he then compared it to naturally occurring copper sulfate and observed they both held the same weight proportions of the elements in the compound. • Proust showed that cupric (copper II) carbonate always had 5.3 parts copper to 1 part carbon to 4 parts oxygen

6. Claude Louis Berthollet • He was born on December 9th, 1748 in the town of Talloires, france He died on November 6th, 1822 • He began his studies at Chambery, but finished his studies at Turin university, where he graduated in medicine. • Was an active participant in the Academy of Science • Went with Napoleon to Egypt, and became a member of the physics and natural history section of the Institutd’Egypt • Was elected a Fellow of the Royal Society of London • In 1801 he was elected as a foreign member of the Royal Swedish Academy of Sciences, and was elected as a Foreign Honorary Member of the American Academy of Arts and Sciences in 1822

7. Berthollet’s Scientific Contribution • Devised a system of names which serves as the basis of the modern system of naming chemical compounds. • Determined the chemical composition of ammonia. • Had an on going feud with Joseph Proust on the law of definite proportions, we already know what Proust thought, but Bertholletthought that the ratio could change due to the ratio of reactants taken in initially. • Specifically, he was puzzled over the natural formation of natron (a hydrated sodium carbonate) from a mixture of limestone (calcium carbonate) and seawater (containing sodium chloride).Reactions with the same components yielded an inverse product.

8. Works Cited • http://scienceworld.wolfram.com/biography/Lavoisier.html • http://science.howstuffworks.com/dictionary/famous-scientists/chemists/joseph-louis-proust-info.htm • http://www.britannica.com/EBchecked/topic/62812/Claude-Louis-Berthollet