Aire. Materiales y materias primas.

Understanding Air: Its Composition and Applications

The Importance of Air

• Air is a vital substance that gives the sky its blue color and distinguishes Earth from other planets in the solar system.

• Beyond being essential for life, air has numerous applications in agriculture, industry, medicine, electronics, metallurgy, and water treatment.

Discovering Air as a Raw Material

• The discussion introduces "amparita," highlighting nitrogen's role in various products like explosives, nylon clothing, and medical practices such as cryosurgery.

• It took humanity hundreds of thousands of years to recognize air's existence and its components.

Historical Understanding of Air

• Early humans utilized air when they learned to create fire by striking stones or rubbing sticks together; this allowed them to cook food and ward off predators.

• Philosophical inquiries into air began in ancient Greece. Anaximenes proposed that air was the fundamental element preceding water.

Philosophical Perspectives on Air

• Empedocles introduced the theory of four primary elements: water, air, fire, and earth. This idea influenced Aristotle’s qualitative physics.

• Leucippus suggested that matter consists of indivisible atoms; his ideas about fullness and emptiness were crucial for atomic theory development.

Scientific Advancements in Understanding Air

• By the 18th century, experiments revealed that air is not a single element but composed mainly of oxygen and nitrogen.

• Alexander von Humboldt studied nature across America while Joseph Gay-Lussac analyzed air samples using Cavendish's method to determine atmospheric composition.

Key Experiments with Air Composition

• Humboldt and Gay-Lussac established laws regarding the volume composition of atmospheric air; they found oxygen levels decrease with altitude.

• Their collaboration also led to discovering water's composition: two parts hydrogen for every one part oxygen.

Practical Applications Related to Temperature Changes

• A practical demonstration shows how blowing through different mouth openings affects perceived temperature due to pressure changes in airflow.

The Evolution of Air Distillation and Its Applications

Historical Context and Key Figures

• The honor attributed to advancements in telegraphy, the compass, and the laying of the first transatlantic cable is discussed. Lord Kelvin, named after a nearby river in Glasgow, played a significant role in these developments.

• The concept of adiabatic expansion is introduced as a process where gas transitions from high to low pressure without heat exchange with its surroundings, exemplified by the operation of a fire extinguisher.

Adiabatic Expansion and Cooling Effects

• Upon expanding gas cools down to form carbon dioxide snow; however, hydrogen behaves differently by increasing in temperature during expansion due to specific temperature thresholds for each gas.

• A historical anecdote about beer consumption in late 19th century Ireland highlights the need for cooling solutions that connect to broader applications like breathing in submarines or tumor destruction techniques.

Innovations by Linde

• In 1894, engineer Carl von Linde developed a revolutionary technique for achieving low temperatures using the Schulttomson effect and counter-current heat exchange, paving the way for cryogenics.

• Linde's fundamental discovery involved separating oxygen from liquid air through an industrializable system based on the Schulttomson effect.

Process of Air Distillation

• Compressed air enters a heat exchanger where it cools before being expanded at medium pressure; part of this air liquefies while another portion continues through the system.

• An additional expansion valve reduces liquid air pressure back to ambient levels, leading to evaporation and further separation processes within supplementary recoverers.

Modern Applications and Components of Air

• Current air distillation processes still rely on Linde's principles: filtering, compressing, and cooling atmospheric air before extracting desired components.

• Purified air is compressed at approximately 6 bar; this compression generates heat which must be managed by cooling it down significantly before further processing.

Fractional Distillation Outcomes

• Liquid air descends through a column where gases are separated based on boiling points; oxygen liquefies first due to its higher boiling point compared to nitrogen.

• Nitrogen evaporates next while argon and other noble gases accumulate mid-column requiring further fractionation for purity.

Composition of Air and Industrial Uses

• The final collection includes various noble gases alongside primary components like oxygen (used extensively across industries), nitrogen (also vital), along with trace amounts of other gases such as carbon dioxide and hydrogen.

Industrial Applications of Oxygen and Noble Gases

The Role of Oxygen in Industry

• Industrial air distillation meets the high-purity oxygen demand for welding and material cutting.

• Oxygen is crucial in metallurgy for metal treatment, oxy-fuel welding, steel production, iron casting, and lead products.

• In environmental technology, pure oxygen is bubbled into highly contaminated water to meet the biological demand of microorganisms like bacteria and fungi.

• The discovery of noble gases in the 18th century revealed that air contains unknown components beyond oxygen and nitrogen.

• The first compounds of xenon with fluorine were synthesized in 1962, leading to the classification of these gases as noble.

Applications of Noble Gases

• Argon is used as an ideal inert gas for protection during welding at low temperatures and in titanium manufacturing.

• Argon lasers have medical applications in dentistry and ophthalmology; helium serves as a filler gas for balloons and military reconnaissance dirigibles.

• Helium acts as a cryogenic coolant near absolute zero temperatures and is used in arc welding and rocket fuel pressurization.

• Krypton and xenon are primarily utilized in strobe lights found on airport runways and camera flashes.

Historical Context: Nitrogen's Dual Role

• Nitrogen has played a dual role: alleviating hunger through fertilizers while also contributing to more efficient explosives during wartime.

• In the 19th century, it became evident that plants needed nitrogen from soil sources like Chilean nitrate deposits or ammonia from coal carbonization.

• Fritz Haber developed a method to synthesize ammonia from atmospheric nitrogen, which was later refined by Carl Bosch for large-scale production.

Impact of Haber-Bosch Process

• The Haber-Bosch process significantly influenced industrial chemistry, laying foundations for other syntheses such as methanol production.

• Fertilizer production skyrocketed from under one million tons annually at the start of the 20th century to about 140 million tons today. Urea remains the most produced nitrogen fertilizer.

Consequences of Ammonia Production

• The availability of ammonia facilitated explosive manufacturing leading up to World War I; Fritz Haber led Germany's chemical warfare efforts during this time.

The Dual Nature of Chemical Compounds in Warfare and Medicine

The Historical Context of Chemical Weapons

• The use of chemical weapons marked a significant moment in warfare history, with the first deployment occurring during this conflict.

• After the war, Fritz Haber sought refuge to avoid extradition for war crimes; he received the Nobel Prize in Chemistry in 1919, awarded for his earlier contributions.

The Dark Legacy of Inventions

• Haber's invention, Cyclone B, was later used by Nazis in gas chambers at Auschwitz, resulting in over a million deaths, including some of Haber's own relatives.

• This juxtaposition highlights the duality of chemical compounds: they can be utilized for both lethal purposes and life-saving medical applications.

Medical Applications of Gases

• Medicinal gases have become essential standards in modern medicine, serving as anesthetics and therapeutic agents.

• Liquid nitrogen is employed in cryosurgery; carbon dioxide is used for superficial surgeries and therapeutic baths.

Composition and Variability of Air

• The composition of air we breathe is defined by a convention established in 1947 but varies based on environmental factors.

• Industrial areas may contain higher concentrations of hydrocarbons like methane and reactive substances such as ethylene that complicate air distillation processes.

Distillation Challenges and Techniques

• Ethylene's presence poses risks during air distillation due to its explosive reactivity with liquid oxygen; thus it must be removed.

• A method to separate ethylene involves passing liquid oxygen through a condenser where temperature differences allow effective separation.

Impact on Food Industry Practices

• The food industry increasingly considers the role of gases like oxygen and nitrogen in food preservation techniques.

• Liquid nitrogen aids high-quality freezing processes for products like hamburgers; CO₂ is crucial for carbonating beverages.

Controlled Atmospheres for Preservation

• Controlled atmospheres reduce oxygen levels while increasing CO₂ to maintain food quality without chemical additives.

• Nitrogen and CO₂ are also used to preserve coffee aroma; enriched oxygen supports fermentation processes vital for beer and vinegar production.

Extending Shelf Life Through Gas Management

• Managing levels of oxygen and CO₂ extends storage possibilities for fresh produce like apples or pears during transport over long distances.

Conclusion: Understanding Air as a Mixture