Dry ice – why is it dangerous, where to get it, how to make it, use it and store it?

Ice in the concept of most people is water frozen at a temperature below 0°C. However, there is a substance that can also take this form, creating dry ice. What it is, what properties it has and where it is used is worth understanding.

What is dry ice?

We are talking about a well-known gas with the chemical formula CO2, which makes up dry ice. It acquires its characteristic solid form due to strong cooling at a temperature of -78.5°C. Its appearance and structure resembles the ice familiar to everyone, which is why it was named that way. However, under normal conditions, when the temperature rises to room temperature, it turns into a gas, bypassing the liquid form. Dry ice is very similar to its water counterpart and has the same color and cooling ability. Moreover, if used incorrectly, it is dangerous to human health.

How is dry ice made?

Special equipment is used for production. Carbon dioxide enters it, where it is cooled, as a result of which it takes on the state of loose snow. This is not the final stage yet. Further, the production of dry ice involves pressing, as a result of which solid cubic-shaped elements are formed. Some craftsmen are trying to recreate this process at home. It must be said that you can make dry ice yourself, but it is a labor-intensive, expensive and dangerous process.

Dry ice - properties

Cooled carbon dioxide acquires a variety of properties, including:

Density 1561 kg/m³.
White color.
The ability to easily turn into steam, remember that dry ice is carbon dioxide.
The ability to cool nearby objects. The temperature of dry ice is -78.5°C.

Explanation of processes

Dry ice is a very simple substance (solid phase CO₂). It is commercially available and is mainly used for transporting food products or cleaning technical surfaces. But in a home laboratory, dry ice turns into an invaluable reagent! The “highlight” of dry ice is that it immediately changes from a solid state to a gaseous state without an intermediate liquid phase (this process is called sublimation).

The sublimation temperature of carbon dioxide is -78.5°C. When dry ice comes into contact with water, it rapidly changes from a solid to a gaseous state. From the outside it looks like boiling, only with brighter and more characteristic steam formation. Moreover, evaporating carbon dioxide is heavier than air (density 1.9768 kg/m³ versus 1.225 kg/m³), and therefore the “smoke” does not rise, but spreads along the surface around the container with water.

When liquid soap is added, the bubbles of the released gas quickly foam it, and a thick foam is formed, filled with white carbon dioxide.

If you put dry ice in a metal spoon, it will jump and rattle. The fact is that on a warm metal surface, dry ice very quickly sublimates, forming pockets of high pressure, which is why our piece of ice “bounces.”

When dry ice sublimates in water, the released carbon dioxide reacts with the water, forming carbonic acid and changing the acidity. This property of dry ice can be used to create beautiful color transformations with indicator solutions. In a neutral environment, indigo carmine is blue, litmus is red-orange, and phenolphthalein is colorless. When sodium hydroxide is added, the medium becomes alkaline and the solutions change color to green, blue and crimson, respectively. When dry ice is added to alkaline solutions, carbonic acid is formed. As a result, the acidity of the solutions increases, the medium becomes neutral and the color of the solutions changes to the original color.

How is dry ice different from regular ice?

If ordinary ice, when heated, begins to melt and turn into water, that is, it takes the form of a liquid, then carbon dioxide in the solid state is instantly transformed into steam. Frozen liquid, which is familiar to everyone, can be held in your hands without much discomfort, which cannot be said about cooled CO2. Without special gloves, it is not easy to withstand prolonged contact with the skin, and you can get various injuries. When using dry ice, these features must be taken into account and safety rules must be followed.

Cooking formula with soda, vinegar, salt

To prepare solid carbon dioxide according to this recipe, you will need to prepare the materials in the correct proportions. Components may not be replaced without permission.

Ratio:

For 25.25 grams of sodium bicarbonate, use 200 ml of 9% vinegar.
When using 30% essence, 87.4 g of soda is used.
At a concentration of 70%, 210 grams of NaHCO3 are used.

To check the correct ratio of the components, heating is carried out. After waiting for the reaction, a small amount of acid is added. When gas is released with a hissing sound, more acid must be added. Pour gently until the mixture subsides.
Excess water from the solution is evaporated on the stove. The action is carefully controlled; when the crust forms, the heating stops. The composition is infused for 5 minutes.
When the crust expands and the solution is tightened with ice, a few drops of boiling water are poured in.
The mixture is stirred, lumps and ice are removed.
The resulting thick mass is placed in a glass jar and placed in the refrigerator.
Cools to a temperature of +15-20 degrees.
If the instructions are followed correctly, a pinch of table salt is added, which activates crystallization. This produces dry ice.

Expert opinion

Advice!

When crystallization does not occur or is weak, the problem is a lack of acetate. There must be more of it in order for solid carbon dioxide to form. As an alternative, it is recommended to use commercial sodium acetate, available in powder form. The recipe will differ from the instructions described above.

The crystals are poured into water - take 5 small spoons for 3 of the same spoons of liquid.
The microwave is set for 10 seconds, if necessary, time is added until the solution becomes clear.
The grains remaining on the walls of the dish are carefully removed.
The mixture is placed in the refrigerator until it cools.
An acetate granule is added to initiate crystallization.

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What is dry ice used for?

This substance is used in a variety of areas of human activity. Some areas where dry ice is used:

Food industry. Dry ice allows you to “shock” food, which preserves its structure and all its healing properties. It is also used when transporting meat, fish and other semi-finished products. Dry ice is used for cocktails and produces a beautiful effect with it.

Medicine. Donor organs and tissues and other biological materials are covered with dry ice.

Sphere of entertainment. At various holidays and parties, cooled gas is used to create the effect of fog creeping across the ground.

Fire extinguishing.

Science and experimental experiments.

In everyday life, for example, to protect against mosquitoes and midges.

Test purchase

After the tragedy at the bloggers' get-together, fearless youth vying with each other began to set up their own experiments - to test how dry ice works. By the way, buying it is not difficult.

There are different ways to use dry ice. In the food industry - for freezing products, cooling and transporting them. Ice is also used in research activities and in the medical industry for storing and transporting medications. And also - for non-abrasive blast cleaning of various surfaces, stripping molded plastics and rubbers, cooling flowers and delaying their blooming...

Dry ice often becomes an attribute of various shows, photo shoots, weddings; a spectacular veil of fog is now often used even at children's parties.

- I need it for a video. We will film in the studio,

— I explain to the seller.

- Of course, come, -

The man answers me.
— Do you need induction training?
Within a few minutes on the other end of the line, I was told the basics of handling dry ice: keep it in an insulated container, use gloves, ventilate the room. I open a second site, where they ask for 80 rubles for 10 kilograms. Let me explain: dry ice is needed for a photo shoot.

“You can use a heavy smoke generator, it will beautifully spread thick fog across the floor,” the seller suggests. I ask about the instructions - the merchant assures that when used correctly, dry ice is completely harmless. Like, you can work with it even indoors. I remind you of the recent tragedy, and he is perplexed:

Where can I get dry ice?

It is not difficult to purchase refrigerated carbon dioxide today. Currently, many companies are engaged in its production and sale. Those wondering where dry ice is sold should check with the appropriate stores, such as Costco, Safeway, Wal-Mart and others. It should be borne in mind that some sellers sell goods only to persons over 18 years of age. It is necessary to buy ice immediately before use, because its shelf life is extremely short, it very quickly turns into a gaseous state.

Making ice with a fire extinguisher

To make your own dry ice, you will need:

fire extinguisher containing carbon dioxide (OC on the label);
fabric bag or thick pillowcase;
channel tape;
protective equipment (insulated gloves, respirator, goggles).

Algorithm of actions:

Wear gloves and protect your respiratory system and eyes.
Wrap the pillowcase around the fire extinguisher nozzle and secure with tape.
Remove the pin, pull the trigger.
Hold it in the working position for 3 to 5 seconds.
A white mist will begin to seep through the material. This is carbon dioxide vapor. They are harmless to humans.
Squeeze the bag tightly. The white foam-like granules that fill the bag or pillowcase are dry ice.
Carefully pour into prepared container.

Carefully! The temperature of the substance is -80 degrees. Do not touch with bare hands, there is a high risk of severe frostbite.

Similarly, you can get frozen pellets from a carbon dioxide cylinder (available in DIY stores or online).

Why is dry ice dangerous?

Its main feature is its low temperature, so it poses a risk of frostbite. You cannot hold it in your hands for a long time, and this is problematic. Protective gloves must be used. Don't forget that dry ice is a gas. When heated, it quickly evaporates and if it was previously placed in a sealed box, for example, a bag, then an explosion may occur if there is excessive vaporization. Experts recommend purchasing it immediately before use and using it immediately, avoiding long-term storage. It is dangerous to inhale the gas as it may cause suffocation. When used indoors, the air will become toxic due to increased concentrations of carbon dioxide.

People in the fog

We are talking about a well-known Instagram blogger in the CIS. The public is divided into two camps: some empathize with the girl, others accuse her of hype: couldn’t the “pharmacy inspector,” as she calls herself, not know about the mortal danger? Judge for yourself: even before blogging, she studied at a medical institute, receiving a diploma with honors in the specialty “Pharmacist”.

On numerous Russian TV programs, the blogger admitted: when the guests began to jump into the thick fog, no one, including her, thought about the danger. In a closed sauna room, solid carbon dioxide CO2 behaved like this: upon contact with chlorinated hot water of the pool, a reaction occurred. A cloud of deadly gas formed over a group of friends - some received chemical burns to the respiratory tract, and three died. In total there were 18 people at the celebration, everything could have ended much worse...

Anastasia Lapko, a researcher at the Laboratory of Applied Biochemistry at the Institute of Bioorganic Chemistry of the National Academy of Sciences, told why the tragedy occurred and what would happen if something like this were repeated, especially for R.

— Dry ice is by no means the substance that we are accustomed to thinking of as ice. This is not frozen water, but carbon dioxide, or carbon dioxide, which is produced in industrial conditions at low temperatures. Under normal conditions, it gradually sublimates or sublimes, that is, it goes from a solid state directly to a gaseous state, bypassing the liquid. But in case of contact with water, dry ice sublimes almost instantly, and a significant amount of carbon dioxide enters the environment, far exceeding permissible levels. As a result, the human body falls into a state of hypoxia, or, more precisely, hypercapnia, which is characterized by headache, nausea, insufficient breathing, loss of consciousness, and at high concentrations of carbon dioxide leads to death.

The Chairman of the Council of Young Scientists of the Department of Chemistry and Geosciences of the National Academy of Sciences also focused on the fact that an important factor is that carbon dioxide is heavier than air and accumulates at the bottom of the room:

How to make dry ice?

To obtain this substance you will need soda and a 70% acetic acid solution. How to make dry ice at home:

Take the above ingredients in equal parts and mix them in a metal container.
You should wait for the reaction to finish with hissing and add a little water to the composition.
Place the dishes on the stove. Evaporate until a film appears on the surface.
Cool the mixture to room temperature and put it in the refrigerator.
A solid substance should form in the container - sodium crystalline hydrate. If any part of the composition remains in liquid form, it must be drained.
Reheat the frozen substance and cool to room temperature, covering with a towel.
Add a little liquid to the composition and the solution will instantly take on a solid form.

Step-by-step instruction

Take a piece of dry ice and place it on a metal spoon. After a few seconds it will begin to bounce and rattle slightly.

Let's throw dry ice into a glass bowl of water - we observe white smoke and the rapid release of gas bubbles.

If you add a few drops of dishwashing liquid to the water, a thick foam of soap bubbles filled with white smoke will appear.

Now take 3 beakers with indicator solutions: indigo carmine (blue color), phenolphthalein (no color) and litmus (red-orange color). Next, add some sodium hydroxide. The solutions changed their color: indigo carmine became green, phenolphthalein - crimson, and litmus - blue. Add a few pieces of dry ice to each glass. After some time, we observe a change in the color of the solutions to the original color.

How to use dry ice?

It is unlikely that anyone will make dry ice at home for transporting or storing food. As a rule, it is made for entertainment. If you are planning a party, you can take chilled carbon dioxide to make cocktails. When food-grade dry ice gets into a glass of liquid, it begins to boil, as if it were boiling. Very beautiful and impressive. It couldn't be easier to make soda from juice and dry ice. One piece is enough to get classic sizzling water.

How to make smoke from dry ice?

There's nothing complicated about it. Dry ice is easy to use; all you need is warm water. It is important not to use a lot of ice in a confined space. Here are the steps to obtain smoke:

Pour warm water into a large metal container.
Add a couple of dry ice cubes.
The water will immediately boil, and a rich smoke-fog will pour out of the container, spreading across the floor of the room.
By lowering the material at different distances, the amount of steam can be adjusted, increasing or decreasing the mist. You can use containers with water of different temperatures for the same purposes.

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How to store dry ice?

If you have dry ice at home, you must follow the storage rules, not forgetting that when this substance evaporates, carbon dioxide is released:

Purchase a special container for these purposes - in the same place where you bought the cooled CO2 itself. It is made of stainless metal or impact-resistant polymer, covered with fine-pored foam. Thanks to this design, the shelf life of ice increases, even if it gradually evaporates in any, even the most airtight container.
If it is not possible to purchase such a container, it is not forbidden to use a portable refrigerator.
Place the cubes in a container made by yourself, the outer shell of which consists of cardboard, and the inner shell is insulated with foam plastic or penoplex. For maximum joint density, you can use sealant. Those who are interested in how long dry ice is stored should answer that it is about 3 days. The container should be placed in a dark and ventilated area. You can take it out onto the balcony in cold weather, or put it in a barn or attic.

The freezer is not suitable for these purposes, since it is not designed for such low temperatures. In addition, it is not equipped with a ventilation system, so it will not be able to ensure the release of accumulated carbon dioxide. For this reason, experts do not recommend leaving a container of dry ice in a confined space. Increased concentrations of gas are detrimental to human health.

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Necessary materials

For the experiment, special materials are prepared, sold in a regular store. There will be no problems with the purchase.

List of materials:

Acetic acid.
Pan, glass.
Cotton cloth or paper napkin.
Glasses or a mask to protect your eyes.
Household gloves.
Baking soda.

The list of components varies depending on the selected recipe. Some people make ice using a fire extinguisher, while others use powdered sodium acetate. The set of elements is specified for each option.

Once the materials are purchased, the CO2 manufacturing process begins. It is important to take precautions for a successful procedure.

Instant recipe

Take a small saucepan and place it on the gas stove.
Vinegar is poured into the bottom, NaHCO3 is poured onto the bottom, and the resulting mixture is stirred.
After achieving homogeneity, pour into a glass and place in the refrigerator for further cooling.

The resulting liquid is called sodium acetate. The proportions of soda and vinegar are the same for a successful recipe.

A frozen mixture of NaHCO3 and acid is taken out of the refrigerator. In this case, the liquid must freeze completely, otherwise it will not be possible to make ice.
Taking sodium acetate out of the refrigerator, the experiment immediately begins.
The mixture is placed on the fire and begins to melt.

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The liquid must be poured into another container; the container is covered with a napkin to prevent premature hardening.

The remaining sodium acetate is taken into the hand to proceed to the next stage of the experiment.

The napkin is removed from the vessel, then the person touches the surface of the liquid with his hand.
After contact with sodium acetate, an amazing transformation into ice will begin.