By Jack Brubaker – Updated Aug 30, 2022
Vladimir_Timofeev/iStock/GettyImages
Carbon dioxide (CO₂) circulates in Earth’s atmosphere at roughly 0.033 percent. It forms during animal respiration and hydrocarbon combustion. Unlike most gases, CO₂ does not liquidate at ambient temperatures; it sublimates—transiting directly from solid to gas.
Density is the mass of a substance per unit volume, expressed in grams per milliliter (g/mL) or grams per cubic centimeter (g/cc). For gases, the metric is usually g/mL due to the small values involved.
At standard conditions (0 °C, 1 atm), CO₂ has a density of 0.001977 g/mL. This is marginally higher than air’s 0.001239 g/mL, making CO₂ slightly heavier and more prone to accumulate in low‑lying areas.
In its solid form—commonly called dry ice—CO₂’s density rises to 1.56 g/mL under standard conditions. For context, liquid water’s density is about 1.00 g/mL, so dry ice sinks when introduced to water.
These values are corroborated by data from the NIST Chemistry WebBook and other reputable chemical databases.
Understanding CO₂ density is essential for applications ranging from climate science to industrial processes.
