While water (H2O) does contain oxygen atoms, it is important to understand that the oxygen atoms in water are already bound to hydrogen atoms, forming a stable molecule. This means that the oxygen in water is not in a form that can be easily separated and utilized for breathing.
To breathe, we require molecular oxygen (O2), which consists of two oxygen atoms bonded together. This molecular oxygen is produced primarily through processes like photosynthesis in plants, where they convert carbon dioxide into oxygen. Oxygen gas is present in the Earth's atmosphere, making it readily available for us to breathe.
While it is technically possible to separate the oxygen atoms from water molecules through a process called electrolysis, it is not an efficient or practical method for obtaining breathable oxygen. Electrolysis involves passing an electric current through water to break it down into its constituent elements, hydrogen and oxygen. However, this process requires a significant amount of energy and specialized equipment.
Furthermore, even if we were able to separate the oxygen from water through electrolysis or any other means, the amount of oxygen obtained would be minuscule compared to the amount of water needed. Water is composed of two hydrogen atoms for every oxygen atom, so extracting a sufficient amount of oxygen from water to sustain human breathing would be extremely challenging and energy-intensive.
Currently, we rely on other readily available sources of molecular oxygen, such as the oxygen present in the Earth's atmosphere, for our breathing needs. Technologies like oxygen concentrators, oxygen cylinders, and plants (which release oxygen as a byproduct of photosynthesis) are used to provide supplemental oxygen in medical or high-altitude settings where the oxygen levels may be insufficient.
In summary, while water does contain oxygen, it is not a practical or efficient source of breathable oxygen. We primarily rely on atmospheric oxygen (O2) for our respiratory needs, and technologies exist to concentrate and supply oxygen when required.