Gases - Oxygen, Hydrogen, CO2 - Chemistry

• Oxygen


  Essential gas for life and combustion.
• Breathed out air


  Air exhaled, contains less oxygen.
• Normal air


  Air with approximately 20.95% oxygen.
• Candle experiment


  Demonstrates oxygen levels in different air.
• Gas jar


  Container used to measure gas changes.
• Water level rise

  Indicates oxygen consumption during combustion.
• Average time


  Mean of multiple time measurements.
• Oxygen percentage calculation


  Formula: (height water rose/height cylinder) * 100.
• Nitrogen


  Major component of air, 78.09%.
• Other gases

  Includes carbon dioxide and noble gases, 0.96%.
• Hydrogen peroxide


  Chemical compound that decomposes into water and oxygen.
• Catalyst


  Substance that speeds up chemical reactions.
• Manganese dioxide


  Catalyst for decomposing hydrogen peroxide.
• Glowing splint test


  Test for oxygen; relights when exposed.
• Combustion


  Chemical reaction producing heat and light.
• Decomposition


  Breakdown of compounds into simpler substances.
• Experimental observations


  Noted changes during scientific investigations.
• Gas collection


  Gathering gas for analysis or testing.
• Investigation


  Systematic study to test hypotheses.
• Diagram


  Visual representation of experimental setup.
• Conclusion


  Summary of findings from an experiment.
• Hydrogen Production


  Generated by magnesium reacting with hydrochloric acid.
• Hydrogen Test


  Burns with a characteristic 'pop' sound.
• Density of Hydrogen


  0.00009 g/cm³, less dense than air.
• Hindenburg Disaster


  Airship explosion in 1937 due to hydrogen.

  
• Hydrogen's Density Advantage


  Less dense than air, enabling airship flotation.
• Hydrogen Flammability


  Extremely flammable, leading to airship safety concerns.
• Helium Replacement


  Chosen for airships due to safety and inertness.
• Density of Helium


  0.0002 g/cm³, less dense than air.
• Density of Oxygen


  0.0014 g/cm³, denser than hydrogen.
• Density of Nitrogen


  0.0013 g/cm³, denser than hydrogen.
• Carbon Dioxide Test


  Bubbles through limewater, turning it cloudy.
• Limewater Reaction


  Turns cloudy when carbon dioxide is bubbled through.
• CO2 Fire Extinguisher


  Extinguishes flame when poured over it.
• Normal Air Experiment


  Measures candle burn time in fresh air.
• Breathed Out Air Experiment

  Measures candle burn time in exhaled air.
• Downward Displacement Method


  Technique for collecting breathed out air.
• Candle Burn Time


  Average time recorded for normal vs. breathed air.
• Gas Jar Usage


  Used to capture and compare air samples.
• Cloudy Limewater Indicator


  Sign of carbon dioxide presence in limewater.