The following essay is available for re-publication in The Conversation.

A deep-frying turkey is a great way to make a delicious Thanksgiving meal. This method of cooking can be dangerous.

Millions of dollars of damage, trips to the ER and even deaths are caused by attempts to deep-fry turkeys. People put frozen turkeys into boiling oil and that's the majority of accidents. If you are going to deep-fry this year, you should thaw and dry your turkey before putting it in the pot. Failure to do so may cause an explosion.

What is the risk of putting a partially frozen turkey in a deep-fryer?

I am a chemist who loves studying plant, animal and fungi compounds. Differences in density are the reason frozen turkeys explode. The density of water is different between its solid, liquid and gas states. You get an explosion when density differences interact in the right way.

Understanding density

The density is how much an object weighs. Imagine holding an ice cube in one hand and a marshmallows in the other. The ice cube is heavier than the other one.

Water is denser than oil when it comes to frying. This has to do with how heavy the atoms are in each liquid and how tightly the molecule pack together.

Water is small and tightly packed together. Oil is much larger and doesn't pack together as well as water. Water and oils are both made of hydrogen and oxygen. Oxygen is heavier than carbon. One cup of water has more atoms than one cup of oil, and those individuals atoms are heavier. Oil floats on top of water because of this. It is not as dense.

Different materials have different densities, liquids, gases, and other materials can have different densities as well. The ice floats to the top because it is less dense than water.

Water becomes steam when it absorbs heat. The volume of steam is 1,700 times that of liquid water. You can see this effect when you boil water. The sound of steam coming out of the kettle can be heard through the whistle.

turkeys are filled with water

A lot of ice is contained in frozen turkeys. It can be from 50% to 80% water. If you thaw a frozen piece of meat, you will see all the liquid that comes out.

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The cooking oil is heated to around 350 degrees. The boiling point of water is 100 C. When the ice in a frozen turkey comes in contact with the hot oil, the surface ice quickly turns to steam.

The transition is not a problem when it happens at the surface of the oil. The steam escapes into the air.

Liquid water forms when the ice inside a turkey absorbs the heat and thaws. The density comes into play here.

The liquid water falls at the bottom of the pot because it is denser than the oil. The water becomes steam when it absorbs heat and energy. The volume expands by 1,700 times when the water molecule spread far apart. The gas wants to rise to the surface quickly because the density of the water has dropped to a fraction of the oil's density.

You get an explosion when you combine the fast change in density with the expansion of volume. The steam expands and rises, blowing the boiling oil out of the pot. It can catch fire if the oil comes into contact with a burner or flame. A fast-burning fire can be caused by droplets of oil catching on fire and quickly setting nearby oil molecules ablaze.

Thousands of accidents like this happen every year. If you decide to deep-fry a turkey for Thanksgiving, you should thaw it and pat it dry. Next time you add liquid to a pan that is filled with oil, you will know why.

The Conversation published this article. The original article can be found here.