I saw this video that says water “expands into” steam and that 1 cup of water can expand into as much as 1600 cups of steam.
But like… Why specifically 1600? Is steam a gas? If it’s a gas it can basically occupy any volume however large, right? The molecules will just go far apart from each other “forever”, no?
This led to a series of increasingly existential questions….
(1) Is steam not a gas? It does look a little like water when it rises from my kettle.
(2) Do different liquids “expand into” different volumes of their gaseous substances?
And more exestentially…
(3) What does the “volume” of a gas even mean if it can expand basically infinitely to “fill any container” as I was taught in school?
This is the YouTube video here: https://youtu.be/-8lXXg8dWHk
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Steam engineer here! 1600 times is just the measured expansion of water, it’s how much it increases in volume.
1. Yes steam is a gas. But, the steam you see rising from your kettle is not 100% steam, it is some percentage water. Once you have steam that is 100% a gas with no entrained liquid water, it is called saturated steam, and when you increase the temperature of that steam it is called superheated steam.
2. Different liquids do expand into different volumes and do so at different temperatures and pressures, this is the basis of refrigeration systems and why you can’t put just any refrigerant into every system, but that is a topic for another time.
2. A gas will expand to fill any container it is in, that is correct, but so will the other gases in the room. You would have regular air mixed in with your steam, like a steam room, you can still breath because there is still air in their.
3. The big part of this expansion is when you are making steam in a sealed system, like a boiler, or steam piping system. If the steam has no where to expand to it increases the pressure on the container. Steam for heating use doesn’t really require much if any pressure at all, but using steam for propulsion or power generation like a steam turbine does require pressure.
4. Going back to volume, the vice versa is true, if you have 1600cu.ft of steam, then turning it back into water only gives you 1 cubic foot. If you do that inside of a sealed container you create a vacuum. If you watch the videos of someone boiling water in a soda can and then placing the soda can in ice water and it rapidly crumples the can, the rapid change in volume of the steam to water caused a vacuum and sucked the can inwards, crumpling it.
Does this make sense? Would you like me to clarify anything?
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