Imploding Can!

Key Concepts

Materials: 
1                  large bowl or pan filled with cold water
1                  empty aluminum soda can
1 pair        tongs
1 pair        gloves
1                  stovetop

OPTIONAL: 1 pan
Note: This activity is best done with adult supervision. Goggles and aprons are also recommended for all participants. 

Activity Directions:
  1. Pour about 100ml of cold water into the can.
  2. Turn the stove to medium-high heat. 
  3. If you are not using a gas stove or coiled electric stove, skip to step 4. If you are using a gas stove or coiled electric stove, it is recommended that a pan is placed on the stove first.
  4. Place the can in the center of the stove (or in the center of the pan if a pan is being used). 
  5. Wait until steam begins leaving the can.
  6. Carefully remove the can from the stove with a pair of tongs.
  7. Quickly dunk the can into the large bowl of cold water by flipping it upside down and submerging the mouth of the can into the bowl. 
  8. The can has imploded!

Discussion Questions & Science Explanations:
  1. What is implosion and what causes it?
    1. Implosion is the sudden collapsing of an object towards its center, where some amount of matter is condensed into a smaller space.
    2. This implosion is caused by an imbalance between the internal pressure inside of the can and the external pressure outside, acting on the can.
  2. What happened when we heated the can?
    1. First, let’s discuss the difference between solids, liquids, and gases, the 3 common states of matter.
    2. Solids consist of molecules that are tightly packed together. Liquids consist of molecules that are packed together, but the molecules are free to slip and slide amongst each other. Gases consist of molecules that are separated and free to move around. As you may know, the amount of energy a substance has increases from a solid to a liquid to a gas. 
    3. When we heat the can and the liquid water inside of the can, we are transferring energy in the form of heat into the can!
    4. Soon enough, the liquid water molecules in the can begin to turn into water vapor, a gas. Since gas molecules are high energy molecules that are free to travel throughout the can, some of the gas molecules end up shooting outside of the can through the opening at the top. 
    5. The gas molecules that stay inside the can bounce off the walls of the can with a lot of energy, causing the internal pressure of the can to steadily rise. 
  3. Was the process of liquid water transforming into water vapor a chemical reaction? And if so, why?
    1. A chemical reaction occurs when the molecular bonds of a substance change. Changing the physical properties of a substance, such as state of matter, isn’t a chemical reaction because the substance is still the same. Some common examples of each include: burning wood (chemical), cooking an egg (chemical), iron rusting (chemical), ice melting (physical), cutting paper(physical), mixing play-doh (physical). 
    2. A change in state from a liquid to a gas is not a chemical reaction because the substance does not change. The liquid water simply increases in temperature and becomes gaseous water vapor, but that water does not actually morph into a different chemical substance.
  4. Why did the can implode when we dunked it in water?
    1. Heat likes to flow from hot to cold. When the can which was just heated on the stove is in contact with cold water, heat energy will flow from the can to the water. As energy is taken away from the water vapor bouncing around in the can, the gaseous water molecules condense into water droplets.
    2. The newly formed water droplets take up much less space than the water vapor. The water droplets, being a liquid, also exert much less pressure on the walls of the can than the water vapor. 
    3. Suddenly, the internal pressure of the can drops. Because the outside pressure acting on the can is greater than the internal pressure inside the can (these two pressures are imbalanced), the can collapses inward until the outside pressure equals the inside pressure!

Additional Experimentation:
  1. Instead of using just cold water, try using ice water! Is there a noticeable difference?
  2. Try using a longer soda can instead of a regular-sized soda can and see if you can spot any differences in their implosions. ​
Suggested video: https://www.youtube.com/watch?v=xg5NiOwf_Zw

​Published 8.21.2020

Author: Alex Zhang