Elemente si combinatii chimice
Elemente si combinatii chimice
Elemente si combinatii chimice
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Methods obtaining O 2<br />
Industrial<br />
Fractioned distilling of liquid air. O2 have b.p. = -182.9 °C and<br />
N2 have b.p. = -195.7 °C, and thus may be ea<strong>si</strong>ly separated one<br />
to each other. Oxygen are kept in steel tubes at pressures of<br />
about 150 atm.<br />
Acidic or alkaline water electroly<strong>si</strong>s. For instance NaOH 15-<br />
20% solutions, by u<strong>si</strong>ng cathode of Fe and anode of graphite. At<br />
cathode are separated H2 and at anode are separated O2. In lab<br />
Small quantities of O2 can be obtained from thermal<br />
decompo<strong>si</strong>tion of some combinations:<br />
- oxides: 2HgO → O2 + 2Hg, 3MnO2 → O2 + Mn3O4 - peroxides: 2BaO2 → O2 + 2BaO<br />
-salts:KClO3→3 / 2O2<br />
+ KCl, 2KMnO4 → O2 + MnO2 + K2MnO4 Other way is from some redox reactions, such as:<br />
4MnO -<br />
4 + 12H + → 5O2 + 4Mn2+ + 6H2O
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