A Brief History of Chemical Reactions

Double Replacement

732 BCE

The Chinese first used the double replacement reaction when making soap. The ancient people heated seashells and then mixed them with plant ash in water:
CaCO3->CO2+CaO
CaO + H2O-> Ca(OH)2
K2CO3+Ca(OH)2->CaCO3 + 2KOH.

Decomposition

729 BCE

Zinc was first isolated in ancient China as a result of the first decomposition reaction: ZnCO3->ZnO+CO2, where zinc carbonate breaks down when heated to form zinc oxide and carbon dioxide.

Single Replacement

475 BCE

This reaction was first discovered in ancient China when copper was first isolated. They used iron to replace the copper in a copper sulfate solution: Cu(SO4) + Fe-> Cu + Fe(SO4).

Early Combustion

290

The Jin Dynasty official Zhang Hua wrote the earliest known account about spontaneous combustion. His book, Record of Strange Things, acknowledged that if oil was left alone, it would ignite spontaneously. This came after several fires which occurred in the arsenal of the Emperor Wu.

Decomposition of Arsenic Minerals

Feb 3, 1250

Albertus Magnus first observed arsenic when arsenic sulfide (As2S3), a metal-like substance, was heated with soap. It is not certain though whether this scientist observed the free element or not.

Combustion and Air

Jan 31, 1650

One of the earliest discoveries in combustion in more recent history was made by Otto von Gueriche, a German Physicist who demonstrated that a candle can't burn without air. He did this with his earlier invention, the air pump, which could suck all the air out of a container. By proving that something cannot burn without air, he began an argument about what would become one of the most important principles of combustion.

Phlogiston Combustion Theory

Feb 2, 1669

The phlogiston theory, proposed by Johann Becher and put together formally with Georg Ernst Stahl, stated that combustion was "the escape of some “inflammable principle” when the “combustible bodies” react with air."

Lavoisier's Combustion Theory

Feb 3, 1777

Antoine-Laurent Lavoisier, a French scientist, performed experiments on phosphorus and sulfur, and observed that each gained weight by combining with air when burned. He realized that combustion required air and was not satisfied with the phlogiston theory. He heated mercury calx and collected a gas, which he called "dephlogisticated air” in which a candle burned vigorously. Knowing that this air was causing substances to burn, he proposed a new theory of combustion that excluded phlogiston.

Synthesis

Jan 31, 1828

Discovered primarily by Friedrich Wöhler when he tried to synthesize ammonium cyanate but instead made urea, a compound formed in the liver. Wöhler first combined silver cyanate(AgOCN) and ammonium chloride(NH4Cl), which resulted in a white crystalline solid that didn't have the properties of NH4OCN. He then tried using lead cyanate(Pb(OCN)2) and ammonium hydroxide(NH4OH) and produced the same thing but with fewer contaminants so that it could be analyzed.