Question

Describe the experiment that led to discovery of Law of conservation of mass?

Answer 1

Lavoisier wrote in 1785:

"Nothing is created, either in the operations of art or in those of nature, and it may be considered as a general principle that in every operation there exists an equal quantity of matter before and after the operation; that the quality and quantity of the constituents is the same, and that what happens is only changes, modifications. It is on this principle that is founded all the art of performing chemical experiments; in all such must be assumed a true equality or equation between constituents of the substances examined, and those resulting from their analysis."

Lavoisier was able to assemble a number of experiments, all done in closed vessels, in which the weight remained constant, within experimental error. This included tin or lead being reacted with oxygen as well as the analysis of mercury calx (HgO). Over the years of his work, Lavoisier had several large burning lenses (which focused the sun's rays), constructed and these were instrumental in reaching the high temperatures need to cause the chemical reactions to take place. (Lavoisier was also able to burn a diamond with a large lens and show that only CO₂ was produced.)