Have you ever seen a hard-boiled egg get sucked inside a glass bottle with a satisfying pop? This classic egg in a bottle experiment uses air pressure to create a surprising science trick that feels like magic!
Egg in a Bottle Experiment
This egg in a bottle experiment explores how air molecules behave when heated and cooled. When hot air inside a glass bottle cools, it decreases in volume, creating low-pressure air. The atmospheric pressure outside the bottle’s mouth pushes the hardboiled egg inside!
Grade Level Recommendation: Best for grades 3-6. This experiment makes a great science fair project!
Supplies:
- 1 hard-boiled egg (completely peeled, slightly wider than the opening of the bottle)
- 1 glass bottle (milk bottle or juice bottle with a narrow mouth)
- 🛑 Matches or lighter (adult supervision required)
- Strips of paper
💡 Note: While glass bottles are preferred, heat-safe plastic bottles can also be used. It’s a good idea to test for safety first. Some plastic bottles may not provide a strong enough seal for the experiment.
Egg in a Bottle Instructions:
Prep the Hardboiled Egg: Make sure the hardboiled egg is completely peeled and slightly wider than the opening of the bottle.
Light the Paper: Take a small strip of paper, light it with a match or lighter, and carefully drop it inside the bottle.
Place the Egg: Quickly place the wider end of the egg down on top of the bottle’s mouth. Make sure it creates a good seal.
Watch the Magic: As the flame goes out, the air pressure decreases inside the bottle, and the atmospheric pressure outside pushes the egg inside the bottle with a pop!
💡Investigate: Try placing the jar in a bowl of hot water. Did it have the same effect?
Egg in a Bottle Science Information:
When you light the strip of paper and drop it into the glass bottle, the flame heats up the air molecules inside. These air molecules move faster and spread farther apart, creating expanding air. This expansion means the air takes up more space, and some escape from the bottle’s mouth before you place the egg on top.
When the flame goes out, the air inside the bottle begins to cool. Cooling causes the air molecules to slow down and come closer together, creating less space between them. This lowers the air pressure inside the bottle and creates what scientists call a partial vacuum.
Outside the bottle, the atmospheric pressure remains the same, and it’s now much higher than the pressure inside the bottle. Air naturally moves from high-pressure to low-pressure areas—but the egg is blocking the opening! So, the atmospheric pressure pushes the egg inside the bottle to balance the pressure difference.
This experiment demonstrates a key property of air pressure: air always moves from an area of high pressure to an area of low pressure until the pressures are balanced. This same principle is seen in real life in weather patterns, airplane wings, and even how we breathe!
Science Fair Connection:
This experiment is perfect for a science fair project! You can explore different ideas of variables like using bottles with different-sized openings, eggs of varying sizes, or testing how hot air versus cold air affects the outcome. Create a diagram of the setup and present your findings with clear observations and data.
Key Science Fair Questions:
- Can other objects (like a small balloon or a ping-pong ball) be used instead of an egg?
- How does the size of the bottle’s opening affect the result?
- What happens if the egg is larger or smaller?
Related Science Experiments to Explore
- Balloon Rocket: Release a balloon and watch it “rocket” along a string to demonstrate how air pressure changes create movement.
- Balloon In A Jar Experiment: Explore how changes in air pressure can cause a balloon to get pulled into a jar!
- Rising Water Experiment: Place a burning candle in the water and watch what happens to the water. A fun way to explore how heat affects air pressure.
- Tea Bag Rocket (Thermal Expansion): This experiment uses a hollow tea bag to demonstrate thermal expansion. When lit on fire, it rises due to the expansion of air inside.
- Can Crusher Experiment: Observe how rapid cooling reduces air pressure inside a heated can, causing it to collapse under external air pressure.
- Hot and Cold Air Balloon Experiment: Use a balloon and a plastic bottle to explore how warm air expands (increasing pressure), while cool air contracts (decreasing pressure).
- Make a Bottle Rocket: Find out what happens when you combine water and air pressure!
- Potato Straw Experiment: Explore how a weak paper straw can become strong enough to puncture a potato using air pressure and forces.
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