Is Steam Truly Invisible or Just a Common Misconception?

[jackle]

When I was at school, some 15 years ago, I was taught that steam was not a gas. This always seemed a very odd thing to say. I think it was based on the idea that it contains suspended water droplets, but wouldn't any gas have suspended droplets near it's boiling point? I'd like to settle this in my mind forever.

Thanks

 

[HallsofIvy]

"Steam", by virtue of the fact that you can see it, is not a gas.

It's not a matter of the fact that steam contains water droplets, it's the fact that steam is water droplets! Water, as a gas (above its boiling point), is not steam.

 

[chroot]

Halls, I have to differ with you.

Steam is, in fact, invisible. It is pure water vapor, and is a gas.

The whitish cloudy stuff you see rising from your pasta pot on the stove is not steam -- it's just air with condensed water droplets in it.

- Warren

 

[russ_watters]

Steam is, in fact, invisible. It is pure water vapor, and is a gas.

The whitish cloudy stuff you see rising from your pasta pot on the stove is not steam -- it's just air with condensed water droplets in it.

- Warren

...and that's the interpretation of thermodynamics texts as well.