The question: Can vinegar make an eggshell disappear?
Make a prediction
What will the egg look and feel like after 2 days in vinegar? Write your guess on the worksheet before you start. Scientists call this a hypothesis.
What you need
1 raw egg
White vinegar (about 1 1/2 cups)
A tall clear glass or jar
A spoon
A ruler or string to measure
Steps
Measure around the middle of the egg and write it down.
Gently place the egg in the glass and cover it with vinegar. Watch for bubbles!
After 24 hours, carefully pour off the vinegar and add fresh vinegar.
After 48 hours, gently scoop the egg out and rinse it. The shell should be gone.
Measure it again and gently feel it. Hold it up to a flashlight!
🔬 Put the naked egg in corn syrup or salt water overnight. Does it shrink or grow?
⚠️ Safety: This egg is for science, not eating. Wash hands after touching raw egg, and handle it over a sink in case it breaks.
What's happening? The science
An eggshell is made of calcium carbonate. Vinegar contains acetic acid. When they meet, they react and make carbon dioxide gas (the bubbles you saw), and the shell slowly dissolves.
What is left is held together by a thin, stretchy membrane. Water from the vinegar can pass through the membrane into the egg, which is why the egg often gets a little bigger. This movement of water is called osmosis.
Think further
What other reaction in this unit made carbon dioxide bubbles?
