why is water displacement method used in collecting oxygen?

why is that water displacement is being used in collecting oxygen and hydrogen gases/

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hp073 years ago

It is basically because gases are lighter than liquids. You could collect any gas using any liquid (assuming they don't react). Water is the most common liquid and so it's used.

The gas will push the water down because it is lighter, thus you can contain the gas without any leak and as tylervitale said, it has stochiometric applications too.

iceng4 years ago
What is the other collecting method ?
tylervitale5 years ago
What frollard said.
Also, beyond the fact that it demonstrates stoichiometry, it allows you to "see" the gas as it's produced. It's one thing to carry in a opaque container and say "this contains hydrogen", and it's another to be able to show exactly what it looks like. (even though it may not look like anything.) Seeing is believing, my friend.
Also, using a graduated container, it allows the easy measurement of exactly how much gas was obtained. Therefore allowing you to apply the ideal gas law.
frollard5 years ago
because water is the source material, and its a really good way to show for the sake of education that there are 2 parts hydrogen gas to every 1 part oxygen gas.

...because gasses float in water...

...because hydrogen and oxygen don't readily dissolve back into the water (in large quantity)...

...because the reservoir being open-topped allows for keeping water pressure in the whole system to push the gasses out when necessary...

It's just a good, elegant design if you intend to keep the gasses separate from one another after they're separated.