What Is Dry Ice Made Of?

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Have you ever seen smoke-like vapors from a container or a theatre performance?  Chances are its dry ice. What exactly is dry ice, and how is it different from regular ice? Let’s explore the mysterious dry ice, its chemical composition, and its unique properties. Learn about the science behind its sublimation process. But before we jump into that let’s back up a little and learn about matter itself.

What is matter?

Matter is anything that has mass and takes up space. Matter is made up of atoms. There are four states of matter we see in our everyday lives. They are:


• Solid: The atoms in solids are very closely and tightly packed. The atoms do not move around freely. They have a defined shape, mass, and volume.
• Liquid: Liquids have loosely packed atoms, therefore, liquids take up the shape of the container they are stored in. They have no definite shape but have definite volume.
• Gas: The atoms in gases are very loosely packed and move around freely. They have no defined shape or volume. The space between atoms is very large.
• Plasma: Plasma is a state of matter commonly observed in the universe. The Sun and other stars are heated balls of plasma.


There are also other lab-made states of matter, like Bose-Einstein condensates and neutron-degenerate matter, but they are not observed in day-to-day life.

The states of matter represented by the arrangement of atoms that make them up
The states of matter represented by the arrangement of atoms that make them up, Credit: Wikimedia/Yelod

Changing states of matter

One of the properties of matter is that it can change states. These are physical changes to matter that can usually be reversed. There are six main changes in the states of matter.


• Freezing: Freezing is the change from liquid to solid. A liquid needs to be lowered to a certain temperature in order to freeze. This temperature is called freezing temperature. An example for freezing is the formation of ice from water.
• Melting: Melting is when a solid turns into a liquid. The temperature required for a solid to melt is called melting temperature. When ice goes back to being water, it is called melting.
• Vaporization: When a liquid is sufficiently heated, it turns into a gas. This happens only when it reaches a temperature called vaporization temperature. Water is heated to its vaporization temperature to form water vapor.
• Condensation: Gases cool down to form liquids in a process called condensation. A cold glass of water kept out for long enough will have drops of water on the glass, because of surrounding water vapor in the air cooling enough to form water on the surface of the cold glass.
• Deposition: When a gas becomes a solid without passing through a liquid phase, it is called deposition. Moist air forms small crystals of ice when it comes in contact with a cold window.
• Sublimation: Sublimation is the reverse of deposition, wherein a solid changes into a gas without passing through a liquid phase. Solid air fresheners, such as the ones found in bathrooms, are an example of sublimation.

Camphor is a waxy solid that undergoes sublimation
Camphor is a waxy solid that undergoes sublimation, Credit: Wikimedia/Salil Kumar Mukherjee

What is dry ice made of?

Dry ice is solidified carbon dioxide. To make it, carbon dioxide is first liquefied under high pressure. The pressure is decreased, which causes some of the carbon dioxide to vaporize. This leads to a drop in temperature that solidifies the remaining carbon dioxide to a snow-like consistency. Dry ice is much colder than regular ice and is used in refrigerators and freezers. It is also used to ship foods like meats and cheeses that need to be kept cool so that they do not spoil.


Dry ice is commonly used in theater productions to produce the effect of fog. Since dry ice is just solid carbon dioxide, it undergoes sublimation to produce fog. It is also denser than air, and so it stays closer to the ground.


The extremely low temperature of dry ice makes it dangerous to handle. It can easily cause frostbite, which is why it needs to be handled with great care.

Dry ice undergoes sublimation to produce fog
Dry ice undergoes sublimation to produce fog, Credit: Wikimedia/Nina Ladygina-Glazounova

Conclusion

Dry ice is compressed carbon dioxide that can reach very low temperatures. It is used as a refrigerant and coolant. Due to its property of sublimation, it is also used to produce fog in theater productions. Since dry ice is much colder than regular ice, it can cause frostbite and needs to be handled with care.

Flesch Kincaid Grade Level: 6.8


Flesch Kincaid Reading Ease: 69.1

Dry ice (no date) Encyclopædia Britannica. Encyclopædia Britannica, inc. Available at:

https://www.britannica.com/technology/dry-ice (Accessed: April 17, 2023).


Developed in conjunction with Claire M. Coyne, S.A.C. (no date) Earth science, States of Matter | Earth Science. Available at:https://courses.lumenlearning.com/suny-earthscience/chapter/states-of-matter/ (Accessed: April 17, 2023).


Change of state of matter (2021) GeeksforGeeks. GeeksforGeeks. Available at: https://www.geeksforgeeks.org/change-of-state-of-matter/ (Accessed: April 17, 2023).


Department of Health (no date) What is Dry Ice? Available at: https://www.health.ny.gov/publications/7081/ (Accessed: April 17, 2023).

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