Lab - Dry Ice

Learning Intentions

  1. To show your understanding of the transition between solid and gas.
  2. To show your understanding of the kinetic molecular theory, as applied to carbon dioxide.


Notes

Dry ice is carbon dioxide (CO2) in a solid form.


Safety Warning

Dry ice is very cold (about −78.5 °C). Do not play around with it. Do not let it touch your skin. Do not put it in your mouth.


Pre-Lab Questions

  1. Water in a beaker comes to a boil.
    1. What state change occurs to the water?
    2. Why does this happen? What is happening at the molecular level as this state change occurs?
  2. Frost forms on the windshield of a car on a cold morning.
    1. What state change occurs to the water?
    2. Why does this happen? What is happening at the molecular level as this state change occurs?
  3. Water droplets form on the outside of a glass of cold water.
    1. What state change occurs to the water?
    2. Why does this happen? What is happening at the molecular level as this state change occurs?
  4. A layer of moisture forms on the inside of a window on a cold winter day.
    1. What state change occurs to the water?
    2. Why does this happen? What is happening at the molecular level as this state change occurs?
    3. Where else does a similar layer of moisture form?
  5. A puddle disappears in the afternoon sun.
    1. What state change occurs to the water?
    2. Why does this happen? What is happening at the molecular level as this state change occurs?
  6. Over a period of months, the ice cubes in the freezer gradually shrink in volume.
    1. What state change occurs to the water?
    2. Why does this happen? What is happening at the molecular level as this state change occurs?
  7. Your tongue sticks to a metal pole on a cold winter day.
    1. What state change occurs to the water in your saliva?
    2. Why does this happen? What is happening at the molecular level as this state change occurs?

Once you have finished the preceding questions, please show your answers to the teacher, who will give you the dry ice pellets.


Lab Questions

  1. Take a pellet of dry ice and gently glide it across the table. Make sure not to drop the pellet off the table, or push it too far.
    1. What state change occurs to the pellet when it touches the table?
    2. Why does this happen? What is happening at the molecular level as this state change occurs?
    3. Why does the pellet glide?
    4. Can you think of 1 (or more) analogies to the gliding of the pellet?
  2. Use tongs to pick up a piece of metal. Touch the metal to a pellet of dry ice.
    1. What state change occurs to the pellet when it touches the metal?
    2. Why does this happen? What is happening at the molecular level as this state change occurs?
    3. Why does it make a noise?
  3. In a 250 mL beaker, add 5 drops of soap to a 200 mL of lukewarm water. Add 1-2 drops of food colouring. Stir until well-mixed. Place a graduated cylinder in a tray, and pour the liquid from the beaker into the graduated cylinder. Add a pellet of dry ice to the water.
    1. What state change occurs to the pellet when it touches the water?
    2. Why does this happen? What is happening at the molecular level as this state change occurs?
    3. What is the substance in the bubbles?
    4. Why is the substance in the bubbles not coloured by the food colouring?

Wash off all your equipment and leave it to dry in the racks at the back of the room.


Assessment

Submit the answers to all the questions (including the pre-lab) on Teams.

Beginning: Answers show very little knowledge of the Kinetic Molecular Theory

Developing: Answers are mostly correct, with a few mistakes

Applying: Answers show a solid understanding of the Kinetic Molecular Theory

Extending: Answers show a sophisticated understanding of the scientific theory underlying the behaviour of the dry ice