Properties of Carbon Dioxide (CO₂)
Carbon Dioxide (CO₂) is a colorless, odorless gas vital for life on Earth and with many industrial applications. It's slightly denser than air.
Physical Properties:
- State: Gas at room temperature. Can be liquefied under pressure, or solidified into "dry ice" at -78.5°C (-109.3°F). Dry ice sublimes (turns directly from solid to gas).
- Color & Odor: Colorless and odorless at typical concentrations.
- Density: About 1.5 times denser than air. This allows it to accumulate in low-lying areas and be "poured."
- Solubility: Moderately soluble in water, forming carbonic acid (H₂CO₃). This is what gives fizzy drinks their slight tang.
- Effect on Flame: Does not support combustion. It's used in fire extinguishers to displace oxygen and smother flames.
Chemical Properties:
- Acidic Oxide: Reacts with water to form carbonic acid, a weak acid: CO₂ + H₂O ⇌ H₂CO₃.
- Reaction with Limewater: Turns limewater (calcium hydroxide solution, Ca(OH)₂) milky due to the formation of insoluble calcium carbonate: CO₂ + Ca(OH)₂ → CaCO₃(s) + H₂O. This is a common test for CO₂.
- Reaction with Alkalis: Reacts with strong alkalis like sodium hydroxide (NaOH) to form carbonates: CO₂ + 2NaOH → Na₂CO₃ + H₂O.
- Reaction with Carbon: At high temperatures, CO₂ can be reduced by carbon to form carbon monoxide: CO₂ + C → 2CO.
The visualizer on the right demonstrates these properties interactively!