Blowing up Balloons!

Key Concepts

Materials: 
1 bottle    Diet Coke
1                   uninflated balloon
1 pack       Pop Rocks (any flavor)
1                   tray

Optional: 1 funnel

Activity Directions:
  1. Pour the package of Pop Rocks into the balloon (using the funnel if you have one).
  2. Place the bottle of Diet Coke on the tray.
  3. While holding the portion of the balloon containing the pop rocks, carefully wrap the mouth of the balloon around the entire mouth of the Diet Coke, making sure that the Pop Rocks do not fall inside the bottle. 
  4. When ready, hold the portion of the balloon containing the Pop Rocks above the Diet Coke so that the Pop Rocks fall in.
  5. Observe what happens! 

Discussion Questions & Science Explanations:
  1. Why do Pop Rocks fizz when we eat them?
    1. When Pop Rocks are made, carbon dioxide gas is added into the liquid mixture at very high pressures. After the mixture solidifies and becomes Pop Rocks, the carbon dioxide bubbles are still trapped inside the candy. When we eat the Pop Rocks, they melt and release the carbon dioxide gas trapped within to create a crackling and fizzing sensation.
    2. Carbon dioxide gas is also found in sodas (which is why they’re called “carbonated”) and is responsible for that fizzing sensation. 
  2. Is soda a mixture? 
    1. Yes, soda is a mixture because it’s a combination of 2+ different substances that are not chemically bonded. They’re just mixed together. Soda is a mixture of water, carbon dioxide, sugar, flavoring and coloring.
  3. But soda is a special type of mixture called a solution. What is a solution?
    1. A solution is a homogenous mixture of two or more substances. Homogenous just means that the mixture is the same throughout. Soda is homogeneous because it looks like it’s all the same thing. 
  4. What happened when you put the Pop Rocks into the Diet Coke?    
    1. It blew up! 
  5. Was this a chemical reaction?
    1. A chemical reaction occurs when the molecular bonds of a substance change and the original substance becomes a different substance. Changing the physical properties of a substance, such as state of matter, isn’t a chemical reaction because the substance is still the same. Examples of what is and isn’t a chemical reaction: burning wood (chemical), cooking an egg (chemical), iron rusting (chemical), ice melting (physical), cutting paper(physical), mixing play-doh (physical). 
    2. This is actually not a chemical reaction. No new gas is created—we’re just releasing the gas that’s already present in the pop rocks and soda. 
  6. Why did it explode?
    1. It explodes because of a process called nucleation. The Pop Rocks contain many small dents and bumps called nucleation sites in which carbon dioxide bubbles in the soda can collect and be released as gas. A ton of bubbles can form very quickly as the pop rocks are poured in, and this release of gas inside the soda creates pressure that shoots it up out of the bottle. 
    2. In addition, the Pop Rocks themselves contain some carbon dioxide. When the Pop Rocks are exposed to moisture (the Diet Coke), the hard candy dissolves, releasing even more carbon dioxide.

Additional Experimentation:
  1. Try  using a different soda instead of Diet Coke.
  2. Use 2 or even 3 packs of Pop Rocks instead of 1. Does anything change? 
  3. Does using different flavors of Pop Rocks affect how much gas is released? 
Suggested video: https://www.youtube.com/watch?v=YGzN0o3I-tA

​Published 7.3.2020

Author: Alex Zhang