Dry ice, formula, molecule, structure, composition, substance:
Dry ice is solid carbon dioxide (carbon dioxide, carbon dioxide, carbon dioxide, carbon monoxide (IV), carbonic anhydride).
Dry ice is the solid form of carbon dioxide, a binary chemical compound of carbon and oxygen, with the formula CO2.
The chemical formula of dry ice is the same as that of ordinary carbon dioxide CO2.
The structure of the dry ice molecule and the structural formula of dry ice are similar to the structure and structural formula of carbon dioxide:
Under normal conditions (atmospheric pressure and room temperature), dry ice turns into a gaseous state, bypassing the liquid phase. However, the transition from solid to gaseous state is quite slow. In this regard, when the substance comes into contact with solid carbon dioxide, frostbite occurs quite quickly, which can become critical.
The sublimation temperature at normal atmospheric pressure is −78.5 °C (194.65 K). During sublimation, it absorbs about 590 kJ/kg (140 kcal/kg) of heat.
In appearance, dry ice resembles regular ice (hence the name) or a snow-like mass. But unlike water ice, it has a temperature of -78.5°C. Has a sour “soda” smell.
Dry ice is compressed into small granules or larger blocks.
The density of dry ice is about 1560 kg/m³.
Dissolves in water. In 100 grams of water, 0.3803 grams of CO2 dissolves at 16 °C, 0.3369 grams of CO2 - at 20 °C, 0.2515 grams of CO2 - at 30 °C. Dissolving in water, it forms carbonic acid H2CO3. The part of carbon dioxide undissolved in water evaporates, causing a rapid decrease in the temperature of the liquid and forming a dense fog over the water, which poses a danger to life and health due to the high content of CO2 in it and a decrease in the volume fraction of oxygen. In turn, the liquid may harden. Dry ice fog hovers above the ground or the surface of an object (liquid, etc.).
Carbon dioxide is non-flammable, but its atmosphere can support the combustion of active metals, for example, alkali metals and alkaline earth metals - magnesium, calcium, barium.
Solid carbon dioxide is non-toxic and non-explosive.
Dry ice (like carbon dioxide) prevents the growth of bacteria, viruses and the rotting of food.
Otherwise, the properties of dry ice are similar to those of carbon dioxide.
Feature of dry ice
This substance is very interesting in its structure. Dry ice can sublimate, that is, it can go from a solid state to a gaseous state, without a liquid phase. The sublimation temperature of dry ice is -78.5 °C.
In stores, dry ice is sold either in briquettes or granules. If you buy it for experiments, it is preferable to choose granules, as they are more convenient to dispense. It should be remembered that this is a consumable item, which means you do not need to buy it in advance. During the day, up to 15% of the mass of dry ice can evaporate. On top of everything else, this is a rather expensive purchase.
Dry ice can be produced in industrial facilities using special equipment. But in small quantities for experiments, it can be made at home.
Safety requirements for handling dry ice:
In terms of the degree of impact on the human body, carbon dioxide belongs to the 4th hazard class according to GOST 12.1.007-76.
Solid carbon dioxide is non-toxic and non-explosive.
Solid carbon dioxide can cause frostbite to the skin and damage to the mucous membrane of the eyes.
Do not handle solid carbon dioxide with unprotected hands. It is recommended to wear safety glasses and gloves when crushing and packaging dry ice.
Operating personnel must have: an insulating hose gas mask, safety glasses, cloth gloves, a padded jacket.
Gaseous carbon dioxide contained in the air of the working area up to 0.5% by volume does not pose a health hazard; at higher levels, it has a harmful effect on human health.
Carbon dioxide is one and a half times heavier than air and can accumulate in poorly ventilated rooms near the floor and in pits, as well as in the internal volumes of equipment for the production, storage and transportation of gaseous, liquid and solid carbon dioxide, reducing the oxygen content in the air, which can cause the phenomenon of oxygen insufficiency and suffocation.
Premises for the production of solid carbon dioxide, as well as premises for storing containers filled with carbon dioxide, must be equipped with general supply and exhaust and emergency ventilation.
(see GOST 12162-77 “Solid carbon dioxide. Technical conditions”, GOST 8050-85 “Gaseous and liquid carbon dioxide. Technical conditions”).
Let's start making dry ice
There is nothing complicated about understanding how to make dry ice at home. You will need two fire extinguishers, thick gloves and an ice bag. The first fire extinguisher will be needed for the experiment itself; here preference should be given to the carbon dioxide model. The second one will be needed as a security measure.
Thick cotton gloves are needed for your own safety. It is also advisable to cover all exposed skin and eyes. During the experiment, the balloon may slip out of your hands.
The cylinder is laid on its side and secured to the floor surface. Then you need to take a canvas bag. Its optimal capacity is 3-4 liters. It should be tied tightly to the neck of the fire extinguisher funnel. You can even use wire.
And how to make dry ice at home. Gently press the fire extinguisher lever, and then hold it for 2 seconds and release. If you have an old-style cylinder in your hands, then you need to unscrew the valve. This is done slowly. The bag will fill in 2-3 minutes. During the experiment, a haze similar to milky fog may accumulate around. There is no need to be afraid of him - he is absolutely harmless.
All work is carried out only with thick gloves. Otherwise, you can easily get burned by low temperatures.
The substance obtained during the experiment looks like dense and crunchy snow, but nevertheless it is not such.
That's all you need to know about how to make dry ice at home.
Using dry ice
We figured out how to make dry ice. But what can it be useful for? In addition to various experiences, it is also useful in everyday life. If you urgently need to cool a large amount of boiling water, say 200 liters, then just throw 1 kilogram of dry ice into it. The water temperature will almost immediately drop to 50-60 degrees.
A small amount of dry ice can keep water cold for up to a day, even in the hottest weather. It is interesting to observe what happens when water comes into contact with dry ice. The reaction of their interaction resembles boiling. But even though dry ice is in the water, you should not touch it. You can simply freeze your fingers.
If you put dry ice in a small container, then close it tightly and shake vigorously, the result will be a real carbonated drink. Bartenders from all over the planet take advantage of this property of the product.
Application area of dry ice
- cleaning surfaces without using abrasive particles;
- freezing vegetables, berries and fruits;
- long-term storage of mushrooms, fish, meat;
- preparation of carbonated drinks, in particular cocktails;
- transportation of products in large quantities;
- branding of horses and cattle;
- safety of food on board aircraft;
- growing vegetables, fruits and plants in a greenhouse environment;
- making baked goods by inhibiting yeast bacteria;
- storing food dry;
- creation of special effects for entertainment purposes (shows, concerts);
- funeral services;
- fight against rodents by expelling them from the hole;
- long-term preservation of flowers in an unopened state;
- dismantling of ceramic tiles and metal parts due to compression and cooling;
- medicine;
- computer industry, in particular, cooling of quickly heating parts;
- safety of production and catch.
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How to store dry ice
Before cooking, make sure you have a container for storing dry ice on hand. By neglecting this advice, you will reduce your own efforts to “no”, since the composition will instantly evaporate.
- An excellent option would be a special container designed for storing frozen products. As a rule, it consists of frost-resistant plastic, which due to its properties is not airtight. Regular ice trays will also work, but they need to be covered with something on top.
- You can also use a thermos, but do not screw it tightly. As the ice evaporates, a large amount of carbon dioxide is formed, as a result of which it will quickly tear off the lid or even explode the thermos. If you choose this method, cover the container, leaving a small gap.
- If you do not have ready-made dishes, prepare a storage tank yourself. Take a small cardboard box and wrap it with tape on all sides so that it acquires a characteristic glossy sheen. This move will preserve the properties of the product. Then line the bottom, sides and top opening lids with dense foam. Attach them with glue or use the same tape.
Important!
Do not use glass or ceramic containers to store ice unless they have sufficient heat resistance. Under the influence of temperatures, the dishes will crack or split into several parts. As for metal containers, their use is not prohibited, but the container may become deformed when in contact with cold.
It is possible to make dry ice at home. Take care of protective clothing, gloves and goggles. Take care of a container for storing the composition in advance, and carry out the procedure outdoors. Handle the fire extinguisher carefully, holding the device firmly in your hands so that it does not fall out after lifting the tap.
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Principles for handling dry ice at home
Due to their ease of use, dry ice pellets are most often used in home experiments. They are usually small in size and easier to dose. By the way, up to 15% of the mass of dry ice evaporates in a plastic container per day. Most experiments with this simplest substance are based on the same principle: when dry ice comes into contact with water, the transition from solid to gas looks like boiling. True, unlike the latter, this vaporization is quite bright and is difficult to confuse with something else. The trick is that since evaporating CO2 is heavier than air, it surrounds the container with water, as if creeping along the surface, unlike ordinary smoke, which rises upward.
For the experiment to be a success, you need to throw a granule or briquette of dry ice into a container of water. The rate of evaporation depends on the temperature of the water - the warmer the water, the shorter and brighter the effect. It is at this point that experiments can be carried out - allowing steam to escape outside or limiting evaporation in a confined space
It is important that you cannot use plastic bottles in such experiments - they may burst, or at best, the ice steam will knock out the cork. This reaction is due to the density of the substance in the gaseous state, which is why it takes up more space.
The safest use of dry ice is to make soap bubbles.
See what happens when you throw dry ice into a swimming pool:
