Back to Library

(AI-Powered Suggestions)

Related Topics

A topic from the subject of Contributions of Famous Chemists in Chemistry.

  • 11 months ago
  • 6 min read
The Exploration of Oxygen: A Comprehensive Guide to Two Pioneering Discoveries
Introduction

In the field of chemistry, the discovery of oxygen holds immense significance. Two names stand tall in this historic feat: Joseph Priestley and Carl Scheele. Let us explore their contributions and the intricate world of oxygen discovery.

Basic Concepts
  • Oxygen: A vital element essential for the survival of most known life forms.
  • Combustion: A process involving the rapid combination of a substance with oxygen, often resulting in the emission of light and heat.
  • Gas Collection: The capture and assembly of gaseous substances for experimentation.
Experiment Equipment and Approaches
  • Mercury Oxide Decomposition: Priestley employed this method by heating mercury(II) oxide (red precipitate) to release oxygen.
  • Heating Manganese Oxide: Scheele's approach involved the thermal treatment of manganese(IV) oxide.
  • Gas Collection Apparatus: Both Priestley and Scheele used water displacement to collect the liberated oxygen.
Experiments and Observations
Joseph Priestley's Experiments
  • Key Observations:
  • Priestley noticed that oxygen supports a brighter, more intense flame.
  • He found that air is capable of undergoing depletion and restoration.
Carl Scheele's Experiments
  • Notable Observations:
  • Scheele's experimentation resulted in the production of oxygen-rich air, providing him with an understanding of the element's various properties.
  • He identified oxygen as an element necessary for respiration and sustaining life.
Data Analysis and Results
  • Variable Gas Behavior: Through their experiments, both researchers observed the contrasting behavior of oxygen compared to other gases.
  • Experimental Confirmation: By noticing the variations in flame intensity, the two scientists gained preliminary insight into the distinct character of oxygen.
Wide-ranging Applications
Early Oxygen Utilization
  • In the medical field, oxygen discoveries revolutionized the treatment of patients requiring oxygen therapy.
  • Beyond medical applications, the steel industry harnessed the power of oxygen to achieve higher temperatures in furnaces for refining metals.
Advancement of Scientific Comprehension
  • Investigations into oxygen paved the way for improved understanding of gas behavior and interactions.
  • The discovery of oxygen laid the groundwork for further breakthroughs in chemistry.
Conclusion

The path-blazing efforts of Joseph Priestley and Carl Scheele unveiled the secrets of oxygen, etching their names indelibly in the annals of scientific history. Their experiments transformed chemistry, paving the way for diverse applications that continue to impact numerous aspects of life. From the medical sphere to manufacturing industries, the discovery of oxygen stands as a testament to the enduring power of scientific inquiry.

The Discovery of Oxygen by Joseph Priestley and Carl Scheele

Overview

  • Oxygen was independently discovered by Joseph Priestley and Carl Scheele in the late 18th century.
  • Their discoveries laid the foundation for modern chemistry and our understanding of combustion and respiration.

Key Points

  • Joseph Priestley
    • English chemist and theologian
    • Conducted experiments with gases
    • Isolated oxygen in 1774 by heating mercuric oxide
  • Carl Scheele
    • Swedish chemist and pharmacist
    • Also conducted experiments with gases
    • Isolated oxygen independently of Priestley in 1772, but his work was not published until later.
  • Main Concepts
    • Oxygen
      • A colorless, odorless, and tasteless gas
      • Makes up about 21% of the Earth's atmosphere
      • Essential for life on Earth
    • Combustion
      • A chemical reaction that produces heat and light
      • Requires oxygen
    • Respiration
      • A process by which living organisms use oxygen to produce energy
      • Requires oxygen

Conclusion

The independent discovery of oxygen by Priestley and Scheele was a major breakthrough in chemistry. It led to a greater understanding of combustion, respiration, and the composition of air. This knowledge has been essential for the development of many modern technologies, including the internal combustion engine and the oxygen tank. While Priestley is often given more credit due to the earlier publication of his findings, Scheele's independent discovery is equally significant. The debate over who deserves more credit highlights the collaborative and often serendipitous nature of scientific discovery.

Experiment: The Discovery of Oxygen by Joseph Priestley and Carl Scheele

Objective: To demonstrate the discovery of oxygen by Joseph Priestley and Carl Scheele and to explore the properties of this essential gas.

Materials:

  • Mercury oxide (HgO)
  • Test tube
  • Test tube holder
  • Bunsen burner
  • Glowing splinter (prepared by extinguishing a match just before it goes out)
  • Water
  • Inverted flask or pneumatic trough (for collecting gas)
  • Matches

Procedure:

  1. Step 1: Preparing the Mercury Oxide:
    • Place a small amount of mercury oxide (HgO) in a clean, dry test tube.
  2. Step 2: Heating the Mercury Oxide:
    • Using a test tube holder, gently heat the test tube containing HgO over a Bunsen burner flame. Heat it evenly to avoid cracking the test tube.
    • Observe the changes that occur in the test tube. You should observe the formation of a silvery liquid (mercury) and the release of a gas.
  3. Step 3: Testing for the Presence of Oxygen:
    • Remove the test tube from the heat (using the test tube holder) and carefully insert a glowing splinter into the test tube's mouth.
    • Observe the behavior of the glowing splinter. If oxygen is present, the splinter should re-ignite and burn brightly.
  4. Step 4: Collecting the Oxygen (Alternative Method using Pneumatic Trough):
    • Fill the inverted flask completely with water and invert it into a pneumatic trough (a container filled with water). Ensure the flask's mouth remains submerged.
    • Position the mouth of the heated test tube (still using the holder) under the inverted flask's mouth in the pneumatic trough.
    • Continue heating the test tube gently. The gas produced will displace the water in the inverted flask.
    • Observe the collection of gas in the flask.

    Note: This method is safer and more efficient than the original description. The original method lacked sufficient detail and presented safety hazards.

  5. Step 5: Testing the Properties of Oxygen:
    • Carefully remove the filled flask from the pneumatic trough, keeping its mouth submerged until it's upright.
    • Quickly light a match and insert it into the flask containing the collected gas.
    • Observe the behavior of the match. The match should burn more vigorously than in normal air.

Key Procedures:

  • Heating mercury(II) oxide (HgO) decomposes it, releasing oxygen gas (O2) and metallic mercury (Hg).
  • The glowing splinter test is a classic test for oxygen; the re-ignition demonstrates oxygen's ability to support combustion.
  • Collecting the gas over water (using the pneumatic trough) shows that oxygen is only slightly soluble in water.
  • The burning match further confirms the presence of oxygen and its role in combustion.

Significance:

  • This experiment demonstrates the discovery of oxygen, a crucial element for respiration and combustion.
  • It showcases oxygen's properties: supporting combustion and being essential for respiration.
  • The experiment highlights the independent contributions of Joseph Priestley and Carl Scheele in discovering and characterizing oxygen.

Safety Precautions:

  • Always wear safety goggles and appropriate gloves during the experiment.
  • Mercury(II) oxide is toxic; handle it carefully and avoid inhaling the dust.
  • Mercury is also toxic and should be handled with extreme caution. Avoid skin contact and inhalation of vapors.
  • Use a test tube holder to prevent burns and avoid direct contact with the hot test tube.
  • Heat the test tube gently and evenly to prevent cracking.
  • Dispose of the chemicals and waste properly according to local regulations.
  • Work in a well-ventilated area.

Share on: