Chemical Reactions Lecture Notes

Introduction

• Importance of chemical reactions:
  • Essential for life and compound formation.
  • Safety precautions: Use safety goggles and maintain a safe distance.

Notable Chemical Reactions

1. Cesium and Water

• Reactivity: Most reactive alkali metal.
• Reaction: Instantly reacts with water, producing cesium hydroxide and hydrogen gas.
• Outcome: Violent reaction, explosive, breaks containers.

2. Briggs-Rauscher Oscillating Clock

• Nature: Oscillating reaction with changing volumes of substances.
• Components: Potassium iodate, melanin acid, manganese sulfate, hydrogen peroxide.
• Process: Color changes between amber and blue due to iodine and iodide concentrations.

3. Diethyl Zinc and Air

• Characteristics: Unstable organo-zinc compound.
• Reaction: Ignites when exposed to air, used in rocket fuel.
• Handling: Requires inert air technique.

4. Red Phosphorus and Bromine

• Nature: Stable on its own, explosive with bromine.
• Process: Reacts before contact, produces phosphorus pentobromide and toxic vapor.

5. Nitrous Oxide and Carbon Disulfide

• Experiment: Known as barking dog.
• Process: Combustion wave creates blue flame and barking sound.
• Safety: Requires lab precautions.

6. Thermite and Dry Ice

• Components: Aluminum and metal oxide.
• Reaction: Exothermic, explosive with dry ice due to rapid vaporization.

7. Elephant Toothpaste

• Safe Experiment: Can be done at home.
• Components: Hydrogen peroxide, soap, yeast.
• Result: Large foam production due to oxygen separation.

8. Pharaoh's Serpent

• Danger: Toxic gases, mercury thiocyanate breakdown.
• Process: Creates ash resembling a serpent.

9. Aluminum and Iodine

• Reaction: Vigorous with water as catalyst.
• Outcome: Purple smoke from iodine evaporation.

10. Hot Ice (Sodium Acetate)

• Concept: Supersaturation principle.
• Result: Crystals form "ice" that releases heat.

11. Halloween Clock

• Process: Instant color change demonstrating redox reaction.
• Components: Includes starch, sodium metabisulfate, mercury ions.

12. Nitric Acid and Copper

• Reaction: Oxidation of copper, releasing toxic nitrogen dioxide.
• Safety: Toxic gas production requires careful handling.

13. Sodium and Chlorine

• Formation of Salt: Violent reaction producing sodium chloride.
• Experiment: Involves chlorine gas and sodium in controlled conditions.

14. Nitrogen Triiodide

• Unstable: Explosive with minimal stimulus (touch, sound).
• Use: No practical application due to instability.

15. Dancing Gummy Bears

• Components: Potassium/sodium chlorate with candy.
• Effect: Violent reaction releasing heat, light, and purple smoke due to sugar oxidation.

Conclusion

• Demonstrations: Highlight the power and complexity of chemical reactions.
• Safety: Emphasized throughout the reactions to manage potential dangers.