Making Dry Ice

Dry ice or card ice is popularly used as a cooling agent in household items and also, as a preserving medium for beverages, vegetables, fish and meat. As compared to regular wet ice, it keeps the items cold and fresh for a longer period. Speaking about dry ice temperature, it measures approximately -109° F (or -78.5° C). Because of this extremely low temperature, dry ice is also applicable to create a cloud like effect in parties and theaters.

Commercial production of dry ice is done by using pure carbon dioxide, which is released as a byproduct of other manufacturing processes (e.g., ethanol plants). If dry ice is required in small amounts, some experienced people try their hands on making it at home. Though an easy procedure, making dry ice at home requires special care and attention. Hence, it is usually not recommended to make dry ice at home. Before discussing the steps of how to make dry ice, let's first understand 'what actually makes up dry ice'.

What is Dry Ice?

Dry ice can be defined as the frozen form of pure carbon dioxide. The name 'dry ice' is given with respect to the direct process of changing its state from solid to gaseous form. As we all know, traditional wet ice (formed after freezing water) melts to water after raising its temperature. And with further increase in temperature, water then boils and turns to vapor or gas state. In short, liquid water is the intermediary step between solid ice and water vapor. Unlike this, dry ice turns directly to carbon dioxide without melting, a phenomenon called sublimation.

How to Make Dry Ice?

Whether you are using dry ice for conducting experiments or just to create smoke for Halloween party, it should be handled carefully. Otherwise, any negligence can lead to permanent damage of skin, eyes and other painful side effects. Some of the safety precautions for handling dry ice are wearing protective glasses and thick leather hand gloves. Do not keep dry ice in an airtight container or it will explode. Also, the room where dry ice is used should be airy and well ventilated. Explained below are the ways in which you can make dry ice at home:

Manufacturing Dry Ice Commercially
The carbon dioxide produced from industrial plants is pressurized, thus converting it into liquid carbon dioxide. Still maintaining the same pressure, this liquid carbon dioxide is kept in an enclosed tank. When exposed to normal temperature, some amount of liquid carbon dioxide gets converted to gaseous carbon dioxide; while the remaining freezes to ice. With hydraulic pressure and a dry ice block press (or pelletizer), dry ice are molded into blocks or pellets. Read more on where to buy dry ice.

Making Dry Ice at Home
There is nothing like dry ice maker for this procedure. Required supplies include safety gears, carbon dioxide extinguisher, tongs, cloth bag and duct tape. After wearing protective gears, lay the cloth bag on a flat work table. Attach the cloth bag opening to the nozzle of the extinguisher. Securing the bag with the duct tape, press down the handle of the extinguisher for 10 -15 seconds, during which the compressed carbon dioxide will fill the cloth bag. As you release the duct tape, the carbon dioxide will solidify in the bag, leading to formation of dry ice. Know more on dry ice experiments.

Always remember to discard unused dry ice outdoors. Use tongs to lift or transfer dry ice and never handle it with bare skin. For safety purpose, consider buying dry ice from the market, rather than making it on your own.