Dry ice is solid carbon dioxide (dioxide), which quickly transforms into steam under atmospheric pressure and room temperature. The liquid phase is bypassed.
Externally,
carbon dioxide really resembles ordinary ice (hence the name). The temperature of "dry ice" is close to -79˚. “Melts”, absorbing 590 kJ / kg. Non toxic It is used primarily for cooling quickly spoiled products during transportation or in the absence of refrigeration chambers.
Dry ice is in demand in mechanical engineering, foundry, in the manufacture of rubber products, in the processing of plastics and polymers, in water / rail transport, in laboratories and other industries (in the restoration of facades, when cleaning wooden surfaces, and cleaning ventilation systems).
Carbon dioxide plants are required for the industrial production of carbon dioxide. Getting dry ice (the price of a kilogram ranges from 35 to 45 rubles, depending on the region and the difficulty in delivery) does not always work. First of all, such factors as the remoteness from the place of production of carbon dioxide and the complexity of transportation (special (thermal) containers are needed) play a role here. But if these problems are still solvable, then what to do with urgency? After all, there are situations when solid carbon dioxide is needed immediately, and it can take not only hours, but a day to find and deliver it.
It turns out that even in a seemingly hopeless situation, you can get time to work for you, within a few minutes by preparing solid carbon dioxide at home.
Want to know how to make dry ice? Everything new, as you know, forgotten old. One has only to recall the school curriculum.
For independent production of a small volume of dry ice, you will need:
- fire extinguisher (carbon dioxide, labeled with type OU, the other is not suitable);
- a bag made of dense cotton fabric;
- mittens (felt or cotton, but very dense);
- a mask to protect the face (or at least glasses).
A carbon dioxide fire extinguisher (OS marking) is already filled with carbon dioxide, which is in a liquid state (under pressure) and reaches a rather low temperature at the outlet (approximately -72 ° C). That is why precautionary measures (gloves, mask) are so important.
Getting down. We take a fire extinguisher, remove the seal from it and remove the safety pin from the handle. We put the bag prepared in advance on the bell, lay the cylinder on the floor (on its side) and carefully, slowly, press the lever. By intermittent frequent presses, we gradually release carbon dioxide. Prior to this, it is important to fix the bag on the bell (just press it by hand), otherwise it will fly off (under pressure) from the first press.
When the bag is full, release the lever and turn the contents inside out - you will see pieces of the very dry ice that we need so much.
Long-term storage of the resulting product is possible only at a temperature of -80 ° C and below. At home, creating such conditions is almost impossible, but you can extend the life of dry ice by creating a semblance of a thermos. A cardboard box laid out inside with polyethylene and polystyrene is quite suitable. Air circulation should be excluded.