Carbon Dioxide – Density – Heat Capacity – Thermal Conductivity

About Carbon Dioxide

Carbon dioxide is a colorless gas with a density about 53% higher than that of dry air. It is relatively nontoxic and noncombustible, but it is heavier than air and may asphyxiate by the displacement of air. When CO2 is solved in water, the mild carbonic acid, is formed. Cooled CO2 in solid form is called dry ice. Carbon dioxide is a minor component of Earth’s atmosphere but important constituent of air. It is a necessary raw material for most plant life, which remove carbon dioxide from air using the process of photosynthesis. A typical concentration of CO2 in air is currently about 0.040% or 404 ppm. The concentration of atmospheric carbon dioxide rises and falls in a seasonal pattern over a range of about 6 ppmv. The concentration of CO2 in air has also been steadily increasing from year to year for over 70 years. The current rate of increase is about 2.5 ppm per year.

Summary

Name	Carbon Dioxide
Phase at STP	gaseous
Density	2 kg/m3
Ultimate Tensile Strength	N/A
Yield Strength	N/A
Young’s Modulus of Elasticity	N/A
Brinell Hardness	N/A
Melting Point	-57 °C
Thermal Conductivity	0.0166 W/mK
Heat Capacity	840 J/g K
Price	2 $/kg

Density of Carbon Dioxide

Typical densities of various substances are at atmospheric pressure. Density is defined as the mass per unit volume. It is an intensive property, which is mathematically defined as mass divided by volume:  ρ = m/V

In words, the density (ρ) of a substance is the total mass (m) of that substance divided by the total volume (V) occupied by that substance. The standard SI unit is kilograms per cubic meter (kg/m³). The Standard English unit is pounds mass per cubic foot (lbm/ft³).

Density of Carbon Dioxide is 2 kg/m³.

Thermal Properties of Carbon Dioxide

Carbon Dioxide – Melting Point

Melting point of Carbon Dioxide is -57 °C.

Note that, these points are associated with the standard atmospheric pressure. In general, melting is a phase change of a substance from the solid to the liquid phase. The melting point of a substance is the temperature at which this phase change occurs. The melting point also defines a condition in which the solid and liquid can exist in equilibrium. For various chemical compounds and alloys, it is difficult to define the melting point, since they are usually a mixture of various chemical elements.

Carbon Dioxide – Thermal Conductivity

Thermal conductivity of Carbon Dioxide is 0.0166 W/(m·K).

The heat transfer characteristics of a solid material are measured by a property called the thermal conductivity, k (or λ), measured in W/m.K. It is a measure of a substance’s ability to transfer heat through a material by conduction. Note that Fourier’s law applies for all matter, regardless of its state (solid, liquid, or gas), therefore, it is also defined for liquids and gases.

The thermal conductivity of most liquids and solids varies with temperature. For vapors, it also depends upon pressure. In general:

Most materials are very nearly homogeneous, therefore we can usually write k = k (T). Similar definitions are associated with thermal conductivities in the y- and z-directions (ky, kz), but for an isotropic material the thermal conductivity is independent of the direction of transfer, kx = ky = kz = k.

Carbon Dioxide – Specific Heat

Specific heat of Carbon Dioxide is 840 J/g K.

Specific heat, or specific heat capacity, is a property related to internal energy that is very important in thermodynamics. The intensive properties c_v and c_p are defined for pure, simple compressible substances as partial derivatives of the internal energy u(T, v) and enthalpy h(T, p), respectively:

where the subscripts v and p denote the variables held fixed during differentiation. The properties c_v and c_p are referred to as specific heats (or heat capacities) because under certain special conditions they relate the temperature change of a system to the amount of energy added by heat transfer. Their SI units are J/kg K or J/mol K.