Oxygen was discovered around 1772 by Carl Wilhelm Scheele, a Swedish chemist, through heating various substances.
While Scheele is credited with the initial discovery, his findings weren't published until later. Independently, Joseph Priestley also discovered oxygen in 1774, and crucially, published his findings first, leading him to often being credited with the discovery, though now it is more commonly attributed to both.
Here's a breakdown of how both Scheele and Priestley independently discovered oxygen:
Carl Wilhelm Scheele's Discovery:
- Method: Scheele obtained oxygen by heating substances like potassium nitrate, mercuric oxide, and other compounds.
- Process: He focused sunlight onto mercuric oxide using a magnifying glass, and observed that it released a gas. He also produced it by heating a mixture of manganese dioxide, sulfuric acid, and arsenic acid.
- Recognition: Scheele named the gas "fire air" because it supported combustion exceptionally well.
- Publication Delay: Although he discovered oxygen around 1772, his findings were not published until 1777 in his book "Chemical Treatise on Air and Fire."
Joseph Priestley's Discovery:
- Method: Priestley discovered oxygen by focusing sunlight on mercuric oxide inside a glass tube.
- Process: Heating mercuric oxide released a gas.
- Recognition: Priestley noticed that a candle burned brighter and mice lived longer in this gas. He initially called it "dephlogisticated air," believing it lacked phlogiston, a then-hypothesized substance believed to be released during combustion.
- Prompt Publication: Priestley published his findings in 1775, which led to his widespread recognition as a discoverer of oxygen.
Antoine Lavoisier's Role:
While Scheele and Priestley discovered oxygen, Antoine Lavoisier is credited with understanding its role in combustion and respiration. He:
- Recognized Oxygen as an Element: Lavoisier conducted quantitative experiments that demonstrated oxygen's role in combustion and respiration.
- Named Oxygen: He named the element "oxygen," derived from the Greek words "oxys" (acid) and "genes" (forming), because he mistakenly believed it was a component of all acids.
- Overthrew the Phlogiston Theory: Lavoisier's work effectively disproved the phlogiston theory, revolutionizing the understanding of chemistry.
In summary, oxygen's discovery involved a series of crucial contributions: Scheele's initial experiments, Priestley's independent discovery and publication, and Lavoisier's crucial understanding of its chemical properties and naming of the element.
