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Carbon dioxide is often mentioned in the context of its increased influence as a greenhouse gas since the pre-industrial (1750) era. In 2013, the increase in CO 2 was estimated to be responsible for 1.82 W m −2 of the 2.63 W m −2 change in radiative forcing on Earth (about 70%). [48]
By mole fraction (i.e., by quantity of molecules), dry air contains 78.08% nitrogen, 20.95% oxygen, 0.93% argon, 0.04% carbon dioxide, and small amounts of other trace gases (see Composition below for more detail). Air also contains a variable amount of water vapor, on average around 1% at sea level, and 0.4% over the entire atmosphere.
The gas constant R is defined as the Avogadro constant N A multiplied by the Boltzmann constant k (or k B): = = 6.022 140 76 × 10 23 mol −1 × 1.380 649 × 10 −23 J⋅K −1 = 8.314 462 618 153 24 J⋅K −1 ⋅mol −1. Since the 2019 revision of the SI, both N A and k are defined with exact numerical values when expressed in SI units. [2]
= milligrams of pollutant per cubic meter of air at sea level atmospheric pressure and T: ppmv = air pollutant concentration, in parts per million by volume T = ambient temperature in K = 273. + °C 0.082057338 = Universal gas constant in L atm mol −1 K −1: M = molecular mass (or molecular weight) of the air pollutant
Carbon dioxide liquid/vapor equilibrium thermodynamic data: Temp. °C P vap Vapor pressure kPa H liq Heat content liquid J/g H vap Heat content vapor J/g
Symptoms of carbon dioxide toxicity, by increasing volume percent in air [45] Carbon dioxide content in fresh air (averaged between sea-level and 10 kPa level, i.e., about 30 km (19 mi) altitude) varies between 0.036% (360 ppm) and 0.041% (412 ppm), depending on the location. [46]
1.438 776 877... × 10 −2 m⋅K: 0 [12] [e] Wien wavelength displacement law constant: 2.897 771 955... × 10 −3 m⋅K: 0 [13] ′ [f] Wien frequency displacement law constant: 5.878 925 757... × 10 10 Hz⋅K −1: 0 [14] Wien entropy displacement law constant 3.002 916 077... × 10 −3 m⋅K: 0
Although Boltzmann first linked entropy and probability in 1877, the relation was never expressed with a specific constant until Max Planck first introduced k, and gave a more precise value for it (1.346 × 10 −23 J/K, about 2.5% lower than today's figure), in his derivation of the law of black-body radiation in 1900–1901. [11]