Brief Description: Using various household materials, students will experiment and observe different chemical reaction and physical changes.

Grades: 5, 6, 7, 8

Time:  1 hour

Keywords: chemistry, chemical engineering, chemical reactions, physical change, matter, phases of matter  


Lesson Objectives

  • Students will understand the difference between a chemical and a physical change

Materials

  • Matches
  • Candles
  • Skim milk
  • Vinegar
  • Baking Soda
  • Sand (2 colors)
  • Raw eggs
  • Hard boiled egg
  • Salt
  • Water
  • Ice cubes
  • Cups
  • Spoons
  • Balloons
  • Graduated cylinders
  • Hot plate
  • Pan

Procedure

  1. Introduce chemical reactions and physical changes.
    1. A chemical change is defined as an irreversible process. It is a change in which one or more new substances are formed. Chemical changes can be indicated by:
      1. Change in temperature (indicating endo/exothermic reactions)
      2. Change in color
      3. Noticeable odor (after reaction has begun)
      4. Formation of a precipitate
      5. Formation of gas
    2. A physical change is reversible, no new products are formed. A change in phase is considered to be a physical change. Physical changes can be indicated by:
      1. Texture
      2. Temperature (a pan can get hot, but it does not change the chemical makeup of it)
      3. Shape
      4. Change of State (Boiling Point and Melting Point are significant factors in determining this change.)
    3. Ask the students if they can think of some examples of each.
  2. Students will explore chemical and physical changes by performing a variety of experiments. Have students record their observations, indicating what happened, what kind of reaction they think it was, and why.
    1. Experiment #1: Vinegar and Baking Soda. After mixing the two in a graduated cylinder, place a balloon over the top to capture the gas.
    2. Experiment #2: Melting of an ice cube and the boiling of water.
      1. H2O(s)H2O(l)
      2. H2O(l)H2O(g)
    3. Experiment #3: Light a match
    4. Experiment #4: Light a candle
    5. Experiment #5: Show the inside of a hard boiled egg and a raw egg.
    6. Experiment #6: Mix two different colors of sand
    7. Experiment #7: Mix vinegar and milk together.
    8. Experiment #8: Mix salt in water.
      1. After students have made their predictions, boil the water until only the salt remains in the pan.
  3. After students have recorded all of their observations and written down what type of change it was, discuss the answers as a class.

Extensions and Modifications

  • Add more experiments (ex: Mentos and diet coke)

Resources

 

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