Question

Write the chemical formula of dry ice. How is it stored? Explain why is it named so?

Answer 1

Hint: It is the solid form of carbon dioxide. Do not get confused with the name as you may be thinking that the formula of normal ice and dry ice would be similar. Dry ice is not formed due to chemical change. Its chemical name is solid $$C{O}_2$$ or frozen carbon dioxide.

Complete step by step answer:
- The chemical formula of dry ice is $$C{O}_2$$.
- Dry ice is basically stored in an insulated container. The thicker the insulation, the slower dry ice will be sublimed.
- It should not be kept in an airtight container as it may explode while subliming from gas to solid state.
- At home, dry ice can be stored in Styrofoam containers, such as cooler and not in a refrigerator freezer as extremely cold conditions will result in switching off the refrigerator by thermostat.
- There should be proper ventilation in the place of storage of dry ice.
- It must be kept at a high pressure condition.
> The reason behind the naming of dry ice: The process of formation of dry ice is directly from solid carbon dioxide to carbon dioxide gas and it does not melt to produce normal ice which is liquid in state as carbon dioxide does not exist in liquid form. There is also a resemblance in its external feature that is white colour and solid chunk like look.
The sublimation temperature of this extremely cool gas is $$-{78}^{\circ }C$$.

Note: Dry ice must be handled with care as its sublimation temperature is very low so it may cause burns due to freezing (frostbite). It is generally used as a cooling agent as it is colder than water ice. $$C{O}_2$$ exists in various phases as seen in the phase diagram. Dry ice is formed in the opposite process of sublimation, where the gaseous state of $$C{O}_2$$ changes into a solid phase.