In industrial furnaces, coal smoke is cleaned, and then alkaline substances are used to absorb carbon dioxide (CO2). Afterward, the mixture is heated to separate the gas from the alkaline solution, and then compressed at a pressure of 70 atmospheres to convert it into a liquid form. Following this, it is allowed to evaporate under low pressure. As a result, solid CO2 is obtained, which is known as dry ice.
Liquid carbon dioxide is stored in thick cylinders and transported to factories that produce carbonated beverages and other facilities that require it. Dry ice, or solid CO2, appears similar to tightly packed snowballs and is used in various fields such as food preservation and firefighting.
The temperature of dry ice is extremely low (-78 degrees Celsius); however, when held in hand, it does not feel overly cold. This is because the CO2 gas escaping creates a barrier between the hand and the dry ice. Only when firmly gripping a piece of dry ice does one experience frostbite. The term “dry ice” primarily describes its physical properties. Dry ice itself never becomes moist or wet any surrounding objects. When exposed to heat, it immediately transforms into gas without passing through a liquid state. This characteristic makes dry ice an excellent food preservative, as the CO2 that adheres to surfaces helps inhibit the growth of microorganisms. Lastly, solid CO2 is a reliable fire extinguishing agent; simply tossing a piece of dry ice into a burning fire can extinguish it.
