Egg in a Bottle
Concept: Pressure. Pressure changes work to force the egg into and out of the bottle.
* hard boiled egg (NO SHELL)
* glass bottle with an opening that the egg will not slip into
* cotton balls (soak with rubbing alcohol or ethanol before use)
* 100 mLbeaker
* baking soda
* pie plate
Directions: To get the egg in the bottle:
1. Demonstrate that the egg will not fit into the bottle.
2. Light an alcohol soaked cotton ball on fire and drop the flaming cotton ball into the bottle.
3. QUICKLY place the egg on top of the bottle and watch the egg get pushed inside the bottle.
Alternative: Is is really necessary to have a combustion reaction to make this demo work? For many years an erroneous explanatioin cited that the egg went into the flask as a result of using up the oxygen. Less gas, less pressure, egg goes into the bottle. In recent years, several articles have been published which state that this explanation is incorrect. Can we prove it?
Is it necessary to have a combustion reaction to get the egg into the bottle? Heat the empty bottle on a hot plate for a short time (several minutes), remove the bottle from the hot plate, place the egg on top of the bottle.
To get the egg out of the bottle:
1. Tip the bottle with the egg in it so that the egg lays near the opening of the bottle (try to aim the egg pointing straight towards the opening of the bottle.)
2. Sprinkle about one teaspoon of baking soda all around the egg (especially on the sides).
3. Pour in (or better use a large turkey baster) about 30 ml of vinegar, and quickly flip the bottle upside down with the egg closing the opening above the pie plate. This procedure may take a little practice to get it down correctly.
Alternative: With the egg in position, holding the bottle upside down, use a hair dryer to heat the bottle. This should force the egg out of the bottle.
Introduction: I have absolutely nothing to put this egg in, besides this bottle here. But there is no way this egg is going to fit in that bottle, right? Well...let's try one more time.
Explanation: The process of combustion (the alcohol burning inside the bottle) causes air inside of the bottle to heat up and expand. Some of the original air is forced out of the bottle before the egg is placed on top. Before the egg is placed on top the air pressure is the same inside and outside of the bottle. When the egg seals the top of the bottle, the flame goes out and the gases on the inside of the bottle begiin to cool. The cooler molecules of gas, move less rapidly, causing less collisions of the gas molecules, which results in less air pressure. However, the air pressure remains the same on the outside of the bottle. This causes the air pressure on the outside of the bottle (which has a greater pressure than the inside of the bottle) to push the egg through the tiny opening and into the bottle.
The reaction between the baking soda and vinegar produces the gas carbon dioxide. The pressure of the carbon dioxide gas pushes the egg back out of the bottle. The gas is able to push the egg out of the bottle because there are now more gas molecules, resulting in more collisions and a increase in air pressure.
alcohol + oxygen -----> carbon dioxide + water
C2H5OH + O2 ----> CO2 + H2O + heat
baking soda + vinegar -------> carbon dioxide + sodium acetate + water
Na(HCO3) + H(C2H3O2)-----> CO2 + Na (C2H3O2) +H2O
Safety: BE CAREFUL when you burn the cotton balls!!! Children should not do this experiment
Waste Disposal: Throw the egg away and dump the rest of the materials down the drain.
Original - Public Domain:
New alternatives and cotton balls - Fortman, J. CHEM 13 NEWS, April 2002, p. 5.
Adcock, Louis H. The Egg in the Bottle Revisited: Air Pressure and Amontons' Law (Charles' Law) J. Chem. Educ. 1998 75 1567. (December 1998)