Removing Oxygen
To remove oxygen from water, the water must be unbonded. Hydrogen and oxygen are atomically bonded to create water. Hence, to separate the oxygen from the hydrogen, the bonds must be separated. This is different from evaporation, which is the just the shifting phase of water to a gas. Water remains water in liquid, solid or gas form. Actually separating oxygen from hydrogen will create two gases.
Why Gas?
Oxygen will only be in a gas form since oxygen in a solid or liquid form requires extreme temperatures and pressure. For example, for oxygen to form a solid, the temperature of the oxygen has to be more than -218 Celsius according to Purdue University. For oxygen to be in a liquid form, oxygen would have to be at -183 Celsius according to the health care firm Medox Healthcare. Hence, oxygen's most natural state, or the state of matter it usually is in because of environmental factors, is a gas form.
Common Ways to Separate
To create gaseous oxygen from water, a common experiment is to perform electrolysis. An electrolysis is an electrical experiment applied to water that separates atoms by their charges through a cathode and an anode. A cathode is a positively charged device while the anode is a negatively charged device. In physics, the water's hydrogen is usually positively charged and oxygen is negatively charged. Thus, when the anode and cathodes are turned on, the oxygen and the hydrogen bonds are broken, separating the two elements. Attached to the electrolysis are two glass tubes, one parallel to the cathode and the other parallel to the anode. Thus, during the experiment, gaseous oxygen will come out through the glass tube on the anode side.
Natural Ways
There is one way oxygen is naturally separated through water and its through organism's respiratory systems. Plants and animals require water to survive and many of them have body systems that separate the oxygen from water. For example, plant photosynthesis is a process where plant cells absorb water and, on a cellular level, the plant cells remove oxygen. As a result, oxygen is released from plants into the atmosphere. According to the biology department at the University of Massachusetts, this process contributed to oxygen eventually becoming a dominant gas in Earth's atmosphere thanks to plants.