lab chem

• Preparation of oxygen gas

  1. Thermal decomposition of potassium chlorate

  2. Using MnO2 catalysts
• Oxygen gas

  • Colorless
  • Odorless
  • Tasteless
  • Low solubility in water
  • Higher density than air
  • 21% oxygen in air by mass
• MnO2

  Catalyst that speeds up the rate of chemical reaction without participating in the reaction
• Oxygen gas evolution

  KClO4 → KCl + 2O2 (g) ↑
• Gas collection by water displacement

  Gas is collected by filling the container with water and inverting. The container must be fully submerged in the water as the gas is introduced to displace the water in the container
• Reaction of oxygen with metals

  1. Cu (s) + O2 (g) → CuO (s)

  2. Fe (s) + 3O2 (g) → Fe2O3 (s)
• Reaction of metal oxides with water

  1. Fe2O3 (s) + H2O (l) → Fe(OH)3 (aq)

  2. Red litmus paper → blue color
• Reaction of oxygen with non-metals

  1. C (s) + O2 (g) → CO2 (g)

  2. CO2 (g) + H2O (l) → H2CO3 (aq)

  3. Blue litmus paper → red color
• Reaction of sodium with water

  Na + H2O → NaOH + H2
• Alkali metals (Group 1)

  React violently with water producing heat and light