Part 1 Law of Conservation of Mass: New Knowledge Changes the Course of Research

In the late-17th century, scientists believe that a substance called phlogiston is released in the process of burning a substance. (Wikipedia.org, 2016).
• Georg Ernst Stahl applied the name phlogiston to J.J. Becher’s 1660 hypothesis (Britannica.com, 2016)

In 1775, French chemist Antoine-Laurent Lavoisier :
• Disproved the existence of phlogiston (American Chemical Society International Historic Chemical Landmarks, 2016)., and
• Discovered the Law of Conservation of Mass (Bohning, J., 1999).

Discovery of the law of conservation of mass helped to turn chemistry into a quantitative science.

Example 1: Before the Law of Conservation of Mass

Aristotle endorsed the belief that there were only 4 elements - air, water, earth, and fire, that made up all matter. (California State University, n.d.).

Alchemists, influenced by Aristotle, believed and were trying to convert metal to gold. (Columbia.edu, 2000).

Scientist and alchemists believed a substance called phlogiston came out of burning material and was released into the air.
(Lavoisier, M., n.d.)

Example 2: Pivotal Change with the Discovery of Oxygen

Beginning around 1770, Lavoisier weighed substances before and after heating them in sealed containers when conducting experiments and determined the substances did not lose weight when burned. (Bohning, J., 1999).

He discovered that the element of oxygen in the air was involved in combustion.

Lavoisier proved by experimentation that water is a compound made up of oxygen and hydrogen, it is not an element as previously thought. Example 3 Present Concepts:
The Law of Conservation of Mass-Energy

This discovery proved to be vital in creating chemical equations and calculations of the weight of elements.

This new quantitative work led to John