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Water in equilibrium with air contains approximately 1 molecule of dissolved O 2 for every 2 molecules of N 2 (1:2), compared with an atmospheric ratio of approximately 1:4. The solubility of oxygen in water is temperature-dependent, and about twice as much (14.6 mg/L) dissolves at 0 °C than at 20 °C (7.6 mg/L).
Oxygen cycle refers to the movement of oxygen through the atmosphere (air), biosphere (plants and animals) and the lithosphere (the Earth’s crust). The oxygen cycle demonstrates how free oxygen is made available in each of these regions, as well as how it is used. The oxygen cycle is the biogeochemical cycle of oxygen atoms between different ...
Oxygen evolution. Oxygen evolution is the process of generating molecular oxygen (O 2) by a chemical reaction, usually from water. Oxygen evolution from water is effected by oxygenic photosynthesis, electrolysis of water, and thermal decomposition of various oxides. The biological process supports aerobic life.
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 ...
This energy heats water in the ocean and seas. Water evaporates as water vapor into the air. Some ice and snow sublimates directly into water vapor. Evapotranspiration is water transpired from plants and evaporated from the soil. The water molecule H 2 O has smaller molecular mass than the major components of the atmosphere, nitrogen (N 2) and ...
The atmosphere has a mass of about 5.15 × 10 18 kg, [3] three quarters of which is within about 11 km (6.8 mi; 36,000 ft) of the surface. The atmosphere becomes thinner with increasing altitude, with no definite boundary between the atmosphere and outer space. The Kármán line, at 100 km (62 mi) or 1.57% of Earth's radius, is often used as ...
If an oxygen atom and an ozone molecule meet, they recombine to form two oxygen molecules: 4. ozone conversion: O 3 + O → 2 O 2. Two oxygen atoms may react to form one oxygen molecule: 5. oxygen recombination: 2O + A → O 2 + A as in reaction 2 (above), A denotes another molecule or atom, like N 2 or O 2 required for the conservation of ...
The common allotrope of elemental oxygen on Earth, O2, is generally known as oxygen, but may be called dioxygen, diatomic oxygen, molecular oxygen, dioxidene or oxygen gas to distinguish it from the element itself and from the triatomic allotrope ozone, O3. As a major component (about 21% by volume) of Earth's atmosphere, elemental oxygen is ...