Physical & Chemical Properties

Physical Properties: How can you use the following physical properties to separate mixtures?

• Color
• Hardness - Moh's Hardness Scale using the scratch test.
  • Harder things can scratch softer things
• Reference: All about Mohs Hardness Scale for minerals
  • Example: Diamond is harder than iron so it will scratch iron. Iron can not scratch diamond.
• Malleability - a material that can be hammered into a thin sheet (becomes more malleable with heat)
• Video: Malleability & Ductility in Metals
• Ductility - a material that can be pulled into thin wire (becomes more ductile with heat)
• Video: Ductility & Fiber Optics
• Viscosity - a liquid substance that resists being poured or pours slowly (becomes less viscous with heat)
• Interactive Website About Viscosity
• Conductivity (heat) - how fast and easily a material passes along thermal energy
  • The closer the atoms and molecules are packed together the more conductive the material.
  • It's all about collisions! More collisions = faster passing along thermal energy.
  • High conductivity means warming up and cooling down fast.
  • High conductivity means having a low specific heat. (Takes less energy to raise the temperature 1^oC)
  • Conductivity (electricity) - a material that passes along electricity quickly and easily
• Density - How tightly packed are the atoms and molecules?
  • Density = mass/volume (SLOPE of a mass vs volume graph)
  • Units are g/mL or g/cm³
  • More dense things sink, less dense things float
  • Density of water = 1 g/mL
• Melting & Boiling Point - every material has its own temperature at which it melts and boils
  • ----> Reference: Interpreting Melting & Boiling Point Tables <----
  • Reference: Interactive Periodic Table - Melting & Boiling Points
  • Magnetism - If a substance is attracted to a magnet
    • Materials made of iron, nickel, cobalt and some rare earth metals and special minerals are magnetic.
  • Solubility - How well something dissolves into a certain liquid
    • More soluble - lots of the material dissolves
    • Less soluble - a little of the material dissolves, the rest sits at the bottom
    • Insoluble - none of the material dissolves
  • Video: What is Solubility
  • Video: Super Saturated Demo

Chemical Properties: Things you can only document when there is a chemical change.

• Flammability: How easily something catches on fire and burns.
• Reactivity: How fast and violently a chemical reacts with other chemicals
  • The faster and more violent the reaction, the more reactive the material
    • Low Reactivity:
      • Milk + Oxygen - spoiling (takes days/weeks)
        • Metal + Oxygen - rusting (can take months/years)
    • High Reactivity:
      • Vinegar + Baking Soda (instantly bubbles)
      • Sodium Metal + Water (instantly bubbles then catches on fire!)
• Toxicity: The degree of which a chemical will damage an organism