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All values refer to 25 °C and to the thermodynamically stable standard state at that temperature unless noted. Values from CRC refer to "100 kPa (1 bar or 0.987 standard atmospheres )". Lange indirectly defines the values to be standard atmosphere of "1 atm (101325 Pa)", although citing the same NBS and JANAF sources among others.
Hydrogen gas is very rare in Earth's atmosphere (around 0.53 ppm on a molar basis [103]) because of its light weight, which enables it to escape the atmosphere more rapidly than heavier gases. However, hydrogen is the third most abundant element on the Earth's surface, [ 104 ] mostly in the form of chemical compounds such as hydrocarbons and water.
Table of specific heat capacities at 25 °C (298 K) unless otherwise noted. [citation needed] Notable minima and maxima are shown in maroon. Substance Phase Isobaric mass heat capacity c P J⋅g −1 ⋅K −1 Molar heat capacity, C P,m and C V,m J⋅mol −1 ⋅K −1 Isobaric volumetric heat capacity C P,v J⋅cm −3 ⋅K −1 Isochoric ...
Liquid hydrogen bubbles forming in two glass flasks at the Bevatron laboratory in 1955 A large hydrogen tank in a vacuum chamber at the Glenn Research Center in Brook Park, Ohio, in 1967 A Linde AG tank for liquid hydrogen at the Museum Autovision in Altlußheim, Germany, in 2008 Two U.S. Department of Transportation placards indicating the presence of hazardous materials, which are used with ...
Thus, each additional degree of freedom will contribute 1 / 2 R to the molar heat capacity of the gas (both c V,m and c P,m). In particular, each molecule of a monatomic gas has only f = 3 degrees of freedom, namely the components of its velocity vector; therefore c V,m = 3 / 2 R and c P,m = 5 / 2 R. [10]
For an ideal gas, the molar heat capacity is at most a function of temperature, since the internal energy is solely a function of temperature for a closed system, i.e., = (,), where n is the amount of substance in moles.
This list includes substances that boil just above standard condition temperatures. Numbers are boiling temperatures in °C. 1,1,2,2,3-Pentafluoropropane 25–26 °C [151] [3] Dimethoxyborane 25.9 °C; 1,4-Pentadiene 25.9 °C; 2-Bromo-1,1,1-trifluoroethane 26 °C; 1,2-Difluoroethane 26 °C; Hydrogen cyanide 26 °C; Trimethylgermane 26.2 °C [96]
To achieve the same increase in temperature, more heat energy is needed for a gram of that substance than for a gram of a monatomic gas. Thus, the specific heat capacity per mole of a polyatomic gas depends both on the molecular mass and the number of degrees of freedom of the molecules. [25] [26] [27]