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R is the gas constant and T is the absolute temperature. Note that pK a = −log(K a) and 2.303 ≈ ln(10). At 25 °C, ΔG ⊖ in kJ·mol −1 ≈ 5.708 pK a (1 kJ·mol −1 = 1000 joules per mole). Free energy is made up of an enthalpy term and an entropy term. [11] =
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Boiling liquid oxygen This is a list of gases at standard conditions , which means substances that boil or sublime at or below 25 °C (77 °F) and 1 atm pressure and are reasonably stable. List
The higher the proton affinity, the stronger the base and the weaker the conjugate acid in the gas phase.The (reportedly) strongest known base is the ortho-diethynylbenzene dianion (E pa = 1843 kJ/mol), [3] followed by the methanide anion (E pa = 1743 kJ/mol) and the hydride ion (E pa = 1675 kJ/mol), [4] making methane the weakest proton acid [5] in the gas phase, followed by dihydrogen.
For gases, departure from 3 R per mole of atoms is generally due to two factors: (1) failure of the higher quantum-energy-spaced vibration modes in gas molecules to be excited at room temperature, and (2) loss of potential energy degree of freedom for small gas molecules, simply because most of their atoms are not bonded maximally in space to ...
The molar gas constant (also known as the gas constant, universal gas constant, or ideal gas constant) is denoted by the symbol R or R. It is the molar equivalent to the Boltzmann constant , expressed in units of energy per temperature increment per amount of substance , rather than energy per temperature increment per particle .
K a is variously named a dissociation constant, [3] an acid ionization constant, [2]: 668 an acidity constant [1] or an ionization constant. [2]: 708 It serves as an indicator of the acid strength: stronger acids have a higher K a value (and a lower pK a value).
The constants listed here are known values of physical constants expressed in SI units; that is, physical quantities that are generally believed to be universal in nature and thus are independent of the unit system in which they are measured.