why/how does pure oxygen become toxic at a certain depth?
478875
Good info Klaus, but you mostly are discussing decompression, in which dissolved gases (usually nitrogen) bubbles out of the blood when going from high to low pressure-Not the reason oxygen is toxic.  The blood requires a certain pressure of oxygen, in other words, and certain number of molecules.  The normal concentration of oxygen in the atmosphere is about 21%, which of course is about perfect.  If you are in an environment that has twice the pressure, you require oxygen at half the concentration, or about 10%.  Its still the same number of molecules total, just a lower concentration.  Clearly, if you are in an environment of 10X the pressure compared to sealevel, you only need a concentration of oxygen of about 2%...again, its still the same number of molecules of oxygen, but because of the greater pressure, there is a lot more total gas molecules present.  Oxygen is a highly reactive molecule, and causes (obviously) oxidation...such as rust on iron.  In the body, this is a toxic effect-More to the point, though, is that the body requires a certain amount of carbon dioxide to maintain the proper acid-base balance.  If far too much oxygen is given, it swamps the ability of hemoglobin to bind CO2, thus causing acidosis-the acidification of the blood.  So, the deeper you dive, the lower *percentage8 of oxygen you require (though again, its the same *amount* of oxygen)- the oxygen is replaced by the most inert gas that can be obtained-helium usually.
891771
YOU KNOW THAT OXYGEN IS COLOURLESS AND ODOURLESS SO YOU CAN'T SEE IT AT THE TIME OF ITS PRODUCTION DURING PHOTOSYNTHESIS;THEREFORE ITS EXPERIMENT IS CARRIED OUT UNDER WATER BECAUSE IN WATER YOU CAN SEE OXYGEN BY FORMATION OF BUBBLES.
429253
If it generates more than 70ppm, then according to the EPA it is unsafe.  Personally, if you can smell the ozone, then it's unsafe.  This means that it's producing at least 30ppm.
561048
Some oxide of chlorine. No idea about which one would be stable at those conditions, though.
102988
Since Oxygen is a gas, it is less dense than water...hense it will float.\n\nIf you produced Oxygen underwater, as it is produced, it will buble up.  If you place some type of container (filled with water) above the bubbles, the Oxygen will collect there and displace (push out) the water.\n\nThis picture should give you the idea,\nhttp://intro.chem.okstate.edu/1314F00/Lecture/Chapter5/Gasoverwater1.GIF
1166728
the water substance drowns the oxygen out of the "would be fire" in the hydrogen peroxide\n\nfire needs O2 to live
952154
Their is more Nitrogen in the air than oxygen, because it is a very stable molecule (N2), it takes a lot of energy to react nitrogen gas with respect to Oxygen, oxygen is very reactive, (it is an oxidizer) so  a lot of reactions can happen  (ie. rust forming or combustion reactions) it is also good to note that because of this, that oxygen is the 2nd most abundant element in the earth's crust primarily found in mineral form (i.e. silicon dioxide = sand)
897385
Typical Oxygen is O2 and it shares 2 electrons with each other. If you need the charge it is -2 meaning it is looking to gain 2 electrons to be neutral.
925123
if the water is at very very low pressure it can become gaseous.\n\nSee also - the triple point of water
868418
# Anoxic autotrophs: Obtain hydrogen from chemicals such as sulfur.\n[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[Dead Zones are areas where the bottom water (the water at the sea floor) is anoxic, meaning that it has very low (or completely zero) concentrations of dissolved oxygen.]]]]]]]]]]]]]]]]]]]]]]]]]\nDead Zones are areas where the bottom water (the water at the sea floor) is anoxic, meaning that it has very low (or completely zero) concentrations of dissolved oxygen. These dead zones are occurring in many areas along the coasts of major continents, and they are spreading over larger areas of the sea floor. Because very few organisms can tolerate the lack of oxygen in these areas, they can destroy the habitat in which numerous organisms make their home.\n\nThe cause of anoxic bottom waters is fairly simple: the organic matter produced by phytoplankton at the surface of the ocean (in the euphotic zone) sinks to the bottom (the benthic zone) where it is subject to breakdown by the action of bacteria, a process known as bacterial respiration. The problem is, while phytoplankton use carbon dioxide and produce oxygen during photosynthesis, bacteria use oxygen and give off carbon dioxide during respiration. The oxygen used by bacteria is the oxygen dissolved in the water, and that’s the same oxygen that all of the other oxygen-respiring animals on the bottom (crabs, clams, shrimp, and a host of mud-loving creatures) and swimming in the water (zooplankton, fish) require for life to continue.\n\nThe "creeping dead zones" are areas in the ocean where it appears that phytoplankton productivity has been enhanced, or natural water flow has been restricted, leading to increasing bottom water anoxia. If phytoplankton productivity is enhanced, more organic matter is produced, more organic matter sinks to the bottom and is respired by bacteria, and thus more oxygen is consumed. If water flow is restricted, the natural refreshing flow of "oxic" waters (water with normal dissolved oxygen concentrations) is reduced, so that the remaining oxygen is depleted faster.\n\nMany of the areas where increasing bottom water anoxia has recently been observed are near the mouths of major river systems. While Satellite images can’t see the bottom of the ocean, they can see the surface, where sediments from rivers mix with ocean waters. The images shown here are Satellite images (SeaWiFS) observations of the Mississippi River delta, the Yangtze River mouth in China (The Yangtze River mouth is not currently identified as an area with an associated dead zone, but such conditions could develop there in the future), and the Pearl River mouth in China, near Hong Kong.\n\nSeaWiFS can also observe areas where water flow is restricted, such as the Baltic Sea in Europe. The image on the left features Denmark after strong storms caused flooding and increased sediment suspension in the Baltic. On the right is an overview of the Baltic Sea, including a plankton bloom in the Skagerrak just north of Denmark.\n\nThe apparent cause of the creeping dead zones is agriculture, specifically fertilizer. While fertilizer is necessary to foster bumper agricultural crops, it also runs off the fields into the streams and rivers of a watershed. When the fertilizer reaches the ocean, it just becomes more nutrients for the phytoplankton, so they do what they do best: they grow and multiply. Which leads to more organic matter reaching the bottom, more bacterial respiration, and more anoxic bottom water.\n\nThese effects can be magnified by catastrophe. When the heavy rains of Hurricane Floyd caused extensive flooding in North Carolina in September 1999, the heavy load of nutrients (from dead animals, flooded animal waste ponds, and numerous other sources) reached the sounds that lie between the coast and the Outer Banks, oxygen levels in the water plummeted. The picture at the top of the page shows the heavy load of sediments flowing into Pamlico Sound. SeaWiFS captur
320348
Deep ocean travel requires two things:\nProtection from the enormous pressure\nAdequate supply of oxygen and breathing gas for the safe return to the surface.\n\nAs we dive deeper, our bodies are subjected to the increasing water pressure.  This is especially so if we dive only to depths of less than 100 meters.  As we dive deeper, our bodies are subjected to greater pressure.  Our blood absorbs MORE gas (namely nitrogen gas); as we return to the surface, the increased amount of nitrogen gas in the bloodstream begins to leave the bloodstream.\n\nIf divers return to the surface too fast, the nitrogen gas will bubble out too fast causing a painful and possibly fatal condition called "The Bends".  So, divers must "acclimate" to sea level pressure slowly.\n\nDivers who dive very deep must remain inside pressure chambers in which the air pressure is slowly reduced to sea level pressure, gently allowing the (bloodstream's) absorbed nitrogen gas to escape safely.
462982
Pulmonary Oxygen Toxicity occurs when a person is exposed to high oxygen levels for over 16 hours in pressures of 0.5 bar or more. It occurs in progressive, overlapping phases. During the first phase, fluid floods into the tissues of the lung that are normally filled with air. Bleeding then occurs between the alveoli, destroying capillaries and epithelial cells. Tissues begin producing in an attempt to heal the area. This causes thickening and scarring of the lungs. \nSymptoms begin with a substernal irritation that becomes progressively worse and is accompanied by an increasingly uncontrollable cough. The patient may experience tracheal or bronchial burning, that worsens during inspiration. Lung damage is sometimes irreversible.
1112275
It comes into contact with oxygen.
1089541
it is blue when exposed to oxygen but otherwise colorless
982375
Hydrogen and oxygen, when combined in an appropriate mixture, will burn to form water.  By itself neither pure hydrogen nor pure oxygen will burn (they need an oxidizer and a reductant respectively).  Water is a stable chemical component that does not have the volatile characteristics of the elements that make up its composition (hydrogen and oxygen).
182902
Specifically, water binds to the mixture, and blocks free oxygen from reaching the material to be oxidized-its a simple smothering reaction, and is why water is effective for putting out fires.  Salt is also effective, but is reduced by the relatively large size of the particles which allows some oxygen in.  There is no specific inhibition of the oxidization reaction other than this-water is neutral to this reaction, except as a space inhibitor.
640954
From 90% to 100% saturated of oxygen (at 2800 meters over sea level)\n\nMeaning your saturation is fine.\n\nWhy do you need it measured?