Chemistry students love dry ice! Use this easy-to-obtain substance to ignite student curiosity and teach a few things as well! Teach kinetic theory, phase changes, changes of state with this laboratory activity.
Start the Experiment!
Put on goggles and gloves.
- Get a 250-ml beaker
- a straw,
- soap solution
- a coin
- a NaOH pipette
- and pipette of universal indicator
For each of the following situations, write down what you observed and a possible explanation for what happened.
1. Take a small piece of dry ice and place it on the table-top. Gently nudge it.
2. Place the dry ice in the beaker. Get the bubble solution and practice blowing bubbles with the straw. When all of the dry ice has changed to vapor, gently blow bubbles and get them to land in the beaker. DON'T blow directly into the beaker.
3. Get another small piece of dry ice from your teacher. Place it on your table. Insert a coin’s thin edge into the ice so that it sticks up in the air. Remove the coin.
4. Place the dry ice in a film canister and put on the lid. QUICKLY, point it away from yourself and others!!
5. Clean out your beaker, then add 25-ml of warm tap water to it. Add 3 drops of Universal Indicator, and then 3 drops of NaOH. Get another small piece of dry ice from your teacher. Add the dry ice to the beaker and observe.
Observations & Explanations for the Teacher
1. For this situation, the dry ice will float across the table like an air-hockey puck. This is because the "warm" table is causing the dry ice to sublime and produce a "cushion" of carbon dioxide gas for the dry ice to float on.
2. The density of the dry ice vapor is higher than the density of regular air, so the bubbles will float on top of the vapor. Since the vapor is invisible, it will appear that the bubbles are floating in the middle of the beaker, unsupported.
3. Placing a coin on edge in the dry ice causes the dry ice to sublime where the "hot" coin touches the ice, causes a burst of vapors to push the coin away. This happens on both sides of the coin in rapid succession, making the coin vibrate.
4. Sublimation inside a closed container builds up gas pressure, which eventually pops the top off of the film canister.
5. Universal indicator will be a violet color in a basic solution of NaOH. As the carbon dioxide interacts with the water, it forms carbonic acid, thus acidifying the solution and causing the indicated color to shift to green and finally to pink.
Dry Ice Explorations
Students love dry ice! Use this easy-to-obtain substance to ignite student curiosity and teach a few things as well!