Is oxygen found pure, by itself?

Question

If it is, where is it found? Isn't it usually mixed with things?

What chemical process is used to extract it in pure form?
If it is found pure, what process is used to concentrate it?

Answer 1

Sure, in the atmosphere. Atomic oxygen (O1) is so reactive that it doesn't last long in that state, but one of the things it can combine with is itself. In that case, you get molecular oxygen (O2), which is still fairly reactive, but also stable enough to build up to measurable levels in the air. In fact, it makes up about 20% of the air we breathe.
****
My mistake. I took "mixed with" to mean "chemically combined with".

If you meant actually on its own, not in a mixture, then no. But then, it's a gas. No atmospheric gases are ever found by themselves. Not even nitrogen. Any gas released into the atmosphere will very quickly diffuse and exist only as a component of the overall air.

And that is correct, the most common industrial method of producing pure oxygen is fractional distillation of liquid air. For smaller quantities, or on-demand needs, electrolysis of water and catalytic chemical oxygen generators (like in airplanes) are frequently used.

Answer 2

Pure oxygen is not found in nature. It is mixed with other gases in the atmosphere, mainly nitrogen. The most common process used to extract it in pure form is fractional distillation from liquid air.

Answer 3

Well, it depends..