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Heating and Cooling Curve of Water

AIM:

Investigate how temperature changes over time when ice is heated from -5oC until it boils and when it is cooled down from the boiling point to the freezing point

HOW DOES IT WORK

Time Allocation: 45 Min

When ice is heated or boiling water is cooled down, the temperature remains constant during state changes. Kinetic energy also remains constant, but the potential energy increases or decreases accordingly. Between state changes, the temperature and kinetic energy changes but the potential energy remains constant. When the water is cooled the potential energy is increased and as the ice is heated the kinetic energy increases.

 APPARATUS

  • 2x 250ml Glass beaker
  • 1 x 1000ml Glass beaker
  • 1 x 150mm -100C/1100C blue fill Thermometer
  • Twister Plus Stove
  • Gas Fuel Cartridge
  • Gauze wire with Ceramic center
  • Stopwatch
  • 300g Ice Crushed
  • 25g Sodium Chloride
  • 50ml Boiling water
  • Glass Stirring Rod 300mm

    METHOD

    Heating Curve
    1. Place ice in a plastic bag and crush it.
    2. Fill beaker 250ml Beaker with 125ml of crushed ice.
    3. Insert thermometer and measure the temperature of the ice
    4. Write down the temperature of the ice.
    5. Put the wire gauze on the Bunsen burner.
    6. Light the Bunsen burner and put the beaker on top of the Bunsen burner.
    7. Measure the temperature change at intervals of 1 minute until the water reaches boiling point.
    8. Continually stir every minute with the glass stirring rod
    9. Tabulate readings
    Cooling curve
    1. Prepare an ice freeze mixture by mixing 25g Sodium Chloride and 100ml of crushed iced (One part salt and 2 parts crushed ice).
    2. Place as much mixture 1000ml beaker as to not overflow a 250ml beaker to be placed inside the 1000ml beaker.
    3. Insert thermometer, and place the smaller beaker (250 ml) into the 1000ml Beaker
    4. Pour 50ml boiling water into 2500ml beaker. Heat until the water is boiling once again.
    5. Measure temperature changes every 1 minute until the mixture is starting to freeze
    6. Swirl so mixture remains cold
    7. Copy the following table and tabulate your results.

    Write down the results for the following:

    Heating Curve

    Reading 1 Reading 2 Reading 3 Reading 4 Reading 5 Reading 6 Reading 7 Reading 8
    Temp. of ice 

     

    Cooling Curve

    Reading 1 Reading 2 Reading 3 Reading 4 Reading 5 Reading 6 Reading 7

    Reading 8
    Temp. of ice

     

    PRECAUTIONS

    • Make sure you are wearing the following protective gear:
    • Safety Goggles
    • Coat or non-flammable clothing
    • Closed shoes
    • Be sure to remain calm at all times during the experiment
    • Keep all students at a safe spectating distance
    • Do not leave any open flame unattended
    • Perform experiment in an isolated environment e.g. a classroom
    • Chemicals
    • In cases where fire spreads , extinguish through smothering flame or the use of a powder extinguisher
    • Do not eat or swallow chemicals
    • In cases where chemical comes into contact with eyes, rinse with eye bath and seek medical attention immediately.