≡Carbon dioxide (CO₂) and dry ice
Carbon dioxide (CO₂) is a gas that can change its state under specific temperature and pressure conditions.
Formation of dry ice:
When CO₂ is cooled below:
❄️ −78 °C
it solidifies and becomes known as:
🧊 dry ice
What happens when dry ice is heated?
At normal atmospheric pressure:
dry ice does not become liquid.
it changes directly from solid to gas.
This process is called:
Sublimation.
When does CO₂ become liquid?
For CO₂ to become liquid, it requires:
pressure greater than 5 atmospheres.
White cloud effect.
When warm air comes into contact with dry ice:
CO₂ gas is rapidly released.
a dense white cloud forms near the ground.
👉 This effect is widely used in theaters and special effects.
Sublimation temperature:
CO₂ sublimates at:
194.7 K.
−78.5 °C.
−109.2 °F.
(at Earth’s atmospheric pressure).
Important precautions:
Dry ice requires care because:
it can cause cold burns on direct contact.
it should not be handled without protection.
Risks in enclosed spaces.
Although CO₂ is not highly toxic:
it can accumulate in closed environments.
it may cause hypercapnia (excess CO₂ in the blood).
this can affect breathing and health.
Did you know?
