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Nitrogen, Sulfur, and the Scientific Method

This brief overview explores the importance of nitrogen and sulfur in the environment and agriculture, alongside the scientific method to understand chemical processes. Nitrogen, comprising 78% of the atmosphere, is essential for plant growth but is largely inaccessible directly from the air. The Haber-Bosch process revolutionized food production through synthetic fertilizers. Sulfur, found as S8 molecules, undergoes various changes with temperature, highlighting its physical and chemical properties. The scientific method is illustrated through experiments on candle combustion, emphasizing inquiry and observation in chemistry.

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Nitrogen, Sulfur, and the Scientific Method

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  1. Nitrogen, Sulfur, and theScientific Method

  2. Nitrogen • Makes up 78% of atmosphere • Necessary for plant growth • Most plants can’t get it from the air

  3. Nitrogen • Makes up 78% of atmosphere • Necessary for plant growth • Most plants can’t get it from the air • Have doubled food production in the last 35 years worldwide • Couldn’t have succeeded with natural fertilizers only • Haber-Bosch process was essential • Found a catalyst to make NH3 out of N2

  4. Nitrogen (cont) • Also important in auto airbags • Uses sodium azide, NaN3 • Electrically decompose it to give off N2 gas in a few hundredths of a second • Synthetic vs. organic fertilizers? • Synthetic use oil or gas that we are running out of • Organic are renewable, but not enough to feed the world.

  5. Sulfur • As a solid, crystal that contains S8 molecules

  6. Sulfur • As a solid, crystal that contains S8 molecules • When heated to 113°C, it melts • Physical change

  7. Sulfur • As a solid, crystal that contains S8 molecules • When heated to 113°C, it melts • Physical change – still S8 • When heated to 159°C, turns brown and becomes viscous • Chemical change – long molecules

  8. Sulfur • As a solid, crystal that contains S8 molecules • When heated to 113°C, it melts • Physical change – still S8 • When heated to 159°C, turns brown and becomes viscous • Chemical change – long molecules • Heating further produces less viscous red liquid • Chemical change – molecules broken into smaller ones

  9. Scientific Method • How does a candle burn? • Make initial observations

  10. Initial Observations • Generates both heat and light • Candle gradually disappears • No other liquid or solid material is produced • Flame is above the top of the wax and encloses the wick • Flame is not uniform throughout • Center is darker than outer portion • Can’t burn solid or liquid wax

  11. Initial Hypothesis • Vapor of the wax is burning. • How can we test? • Put a tube in the flame and draw off what is closest to the wick

  12. Further support, when you extinguish, can you light vapors again?

  13. Candle disappears over time • Doesn’t follow the law of conservation of mass? • Products are gases? • Tests? • Where does the oxygen come from to make CO2 and H2O? • Test?

  14. Why soot? • Incomplete combustion Why? • Different colors of flame, Why? • Test?

  15. H6 – C2 • 22, 23, 32 - 35, 52, 57, 59

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