The chemical formula of dry ice is CO₂. Dry ice is the solid form of carbon dioxide: each molecule contains one carbon atom bonded to two oxygen atoms. At normal atmospheric pressure, it does not melt into a liquid puddle like ordinary water ice. Instead, it changes directly from solid CO₂ into carbon dioxide gas through a process called sublimation.
This guide explains seven useful facts about dry ice, including its formula, temperature, fog effect, production, common applications and safe handling. If you are new to the subject, you can also read our complete guide to what dry ice is.
Quick answer: what is the chemical formula of dry ice?
The chemical formula is CO₂. “Dry ice” is simply the common name for solid carbon dioxide. The formula does not change when carbon dioxide changes state: CO₂ can exist as a gas, liquid under suitable pressure, or solid dry ice.
- Chemical formula: CO₂
- Physical state: Solid carbon dioxide
- Sublimation temperature at normal atmospheric pressure: approximately −78.5°C (−109.3°F)
- Main behavior: changes directly from solid to gas instead of forming liquid meltwater
- Common uses: cold-chain transport, frozen-food cooling, laboratory shipments, events and selected industrial processes
Fact 1: dry ice is solid carbon dioxide, not frozen water
Regular ice is frozen water and has the formula H₂O. Dry ice is completely different: it is solid carbon dioxide with the formula CO₂. That difference explains why the two materials behave differently in storage, transport and cooling applications.
Because dry ice is CO₂ rather than water, it does not leave a pool of liquid water as it disappears. This can be useful when moisture around the payload is undesirable, although the cold temperature and carbon dioxide gas still require appropriate packaging and ventilation.
Fact 2: dry ice sublimates instead of melting
At normal atmospheric pressure, dry ice changes directly from a solid into gas. This phase change is called sublimation. It is the reason a dry ice pack gradually becomes lighter even when there is no liquid leaking from the box.
Sublimation begins as soon as dry ice is exposed to a warmer environment. The rate depends on factors such as quantity, pellet size, insulation, outside temperature, air movement and how often the container is opened. For practical planning, use our dry ice quantity calculator as a starting estimate rather than assuming one universal duration.
Fact 3: dry ice is extremely cold at about −78.5°C
Dry ice is approximately −78.5°C (−109.3°F) at normal atmospheric pressure. That is far colder than ordinary water ice, which is why dry ice can provide strong cooling for selected frozen-food, cold-chain, laboratory and industrial applications.
The same temperature also creates a handling hazard. Direct skin contact can cause a cold burn or frostbite-like injury. Use insulated gloves or suitable tools and avoid holding pellets in bare hands. Our Dry Ice Safety & Handling Guide covers ventilation, PPE, transport and storage precautions.
Fact 4: the visible “smoke” is not carbon dioxide smoke
Carbon dioxide gas itself is invisible. The familiar white cloud seen in dry ice demonstrations is mainly a fog of tiny water droplets. When dry ice is placed in warm water, very cold CO₂ and surrounding air cool water vapour rapidly, producing a dense low-lying fog.
This is why dry ice is popular for stage, event and photography effects. The visual effect can be dramatic, but the same ventilation rules still apply because carbon dioxide gas can accumulate in poorly ventilated or confined spaces. See our dry ice applications guide for more use cases.
Fact 5: dry ice is produced from pressurized carbon dioxide
Commercial dry ice production starts with carbon dioxide that is compressed and liquefied under pressure. When liquid CO₂ is expanded to a lower pressure, part of it rapidly cools and forms carbon dioxide “snow.” That snow is then compressed or extruded into usable dry ice forms such as pellets.
This is more accurate than saying carbon dioxide gas is simply cooled to −78.5°C until it freezes. Pressure and controlled expansion are important parts of the production process.
Fact 6: dry ice is useful because it combines strong cooling with no liquid meltwater
Dry ice is used where very low temperatures or moisture-free cooling can be useful. Common examples include transporting frozen food, supporting selected laboratory and medical shipments with an approved protocol, maintaining cold-chain loads, creating fog effects and supplying industrial cooling or cleaning processes.
Dry Ice Pakistan supplies pellet dry ice for retail and business requirements. Retail box sizes include 2kg, 5kg, 10kg, 15kg and 20kg, while bulk supply and specialized 3mm pellets are available for suitable industrial requirements. Product availability, packaging and delivery should be confirmed for the required date and location.
Fact 7: dry ice must never be sealed in an airtight container
As dry ice sublimates, solid CO₂ becomes gas and needs room to escape. An airtight container can build dangerous pressure. Dry ice should therefore be stored and transported in an appropriate insulated container that is not pressure-tight.
Ventilation is equally important. Carbon dioxide can displace oxygen in enclosed spaces, so avoid keeping significant quantities in a sealed room or unventilated vehicle. Keep dry ice away from children, never ingest it and follow workplace or carrier rules for larger shipments.
Dry ice vs regular ice: the key differences
- Formula: dry ice is CO₂; regular ice is H₂O.
- Temperature: dry ice is about −78.5°C at normal atmospheric pressure; ordinary ice is much warmer.
- Phase change: dry ice sublimates into gas; water ice melts into liquid water.
- Residue: dry ice leaves no liquid meltwater, while regular ice does.
- Safety: both require sensible handling, but dry ice additionally needs CO₂ ventilation and pressure precautions.
For a broader comparison, read Dry Ice vs Regular Ice vs Gel Packs.
What is dry ice used for in Pakistan?
In Pakistan, dry ice is commonly requested for frozen-food transport, ice cream and dessert logistics, laboratory samples, selected pharmaceutical cold-chain requirements, events and fog effects, freezer support, shipping frozen items and industrial processes. The correct quantity depends on the application, route time, insulation and external temperature.
For time-sensitive or regulated goods, dry ice should be treated as one part of the cooling system rather than a guarantee by itself. The shipper or product owner should follow the temperature range and packaging protocol that applies to the actual payload.
How long does dry ice last?
There is no single duration that applies to every box. Sublimation changes with the amount of dry ice, insulation quality, ambient heat, pellet size, empty space and lid-opening frequency. A larger mass generally provides more cooling reserve under comparable conditions, but the relationship is not perfectly linear.
If duration matters to your shipment, review our guide on how long dry ice lasts and validate critical shipments using the actual container and route conditions.
How to handle dry ice safely
- Wear insulated gloves or use suitable handling tools.
- Keep the storage and transport area well ventilated.
- Never seal dry ice in an airtight container.
- Keep it away from children and never ingest it.
- Use an insulated box that can safely vent CO₂ gas.
- For commercial or regulated transport, follow the applicable carrier, workplace and shipment requirements.
Need dry ice for your application?
Dry Ice Pakistan supplies dry ice pellets for retail packs and business requirements. Whether you need dry ice for frozen food, cold-chain transport, laboratory use, events or an industrial application, confirm the required quantity, packaging, location and timing before dispatch.
View current options on our dry ice products page or contact us on WhatsApp 0300-8260063. Prices and delivery availability can vary by location and urgency.
Final takeaway
The most important fact is simple: dry ice is solid carbon dioxide, and its chemical formula is CO₂. Its approximately −78.5°C temperature, direct solid-to-gas sublimation and lack of liquid meltwater make it useful across cold-chain, food, laboratory, event and industrial applications. Those same properties also mean safe handling, ventilation and non-airtight storage are essential.
