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Oxygen began building up in the atmosphere at approximately 1.85 Ga. At current rates of primary production, today's concentration of oxygen could be produced by photosynthetic organisms in 2,000 years. [4] In the absence of plants, the rate of oxygen production by photosynthesis was slower in the Precambrian, and the concentrations of O 2 ...
Oxygen gas is the second most common component of the Earth's atmosphere, taking up 20.8% of its volume and 23.1% of its mass (some 10 15 tonnes). [18] [69] [d] Earth is unusual among the planets of the Solar System in having such a high concentration of oxygen gas in its atmosphere: Mars (with 0.1% O 2 by volume) and Venus have much less. The O
Equation of state. In physics and chemistry, an equation of state is a thermodynamic equation relating state variables, which describe the state of matter under a given set of physical conditions, such as pressure, volume, temperature, or internal energy. [1] Most modern equations of state are formulated in the Helmholtz free energy.
It is produced through deuteron bombardment of nitrogen-14 using a cyclotron. [22] 14 N + 2 H → 15 O + n. Oxygen-15 and nitrogen-13 are produced in air when gamma rays (for example from lightning) knock neutrons out of 16 O and 14 N: [23] 16 O + γ → 15 O + n 14 N + γ → 13 N + n. 15 O decays to 15 N, emitting a positron. The positron ...
Kleiber's plot comparing body size to metabolic rate for a variety of species. [1] Kleiber's law, named after Max Kleiber for his biology work in the early 1930s, is the observation that, for the vast majority of animals, an animal's metabolic rate scales to the 3⁄4 power of the animal's mass. [2] More recently, Kleiber's law has also been ...
Infobox references. Singlet oxygen, systematically named dioxygen (singlet) and dioxidene, is a gaseous inorganic chemical with the formula O=O (also written as 1. [O. 2] or 1. O. 2), which is in a quantum state where all electrons are spin paired. It is kinetically unstable at ambient temperature, but the rate of decay is slow.
Local-density approximations (LDA) are a class of approximations to the exchange – correlation (XC) energy functional in density functional theory (DFT) that depend solely upon the value of the electronic density at each point in space (and not, for example, derivatives of the density or the Kohn–Sham orbitals).
Together with hydrogen (H 2), oxygen is evolved by the electrolysis of water. The point of water electrolysis is to store energy in the form of hydrogen gas, a clean-burning fuel. The "oxygen evolution reaction (OER) is the major bottleneck [to water electrolysis] due to the sluggish kinetics of this four-electron transfer reaction."