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Science, Maths & Technology


Updated Monday, 26th September 2005

We explain how water changes state into steam

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When water converts into steam it does so at its boiling point.

At sea level water boils at 100 degrees Celsius, but this can vary depending on altitude and air pressure.

Norris Geyser basin, Yellowstone [Image: Gouldy99 under CC-BY-NC-ND licence] Creative commons image Icon Gouldy99 via Flickr under Creative-Commons license
Steam rising from the Norris Geyser Basin, Yellowstone Park [Image: Gouldy99 under CC-BY-NC-ND licence]

The high boiling point of water is also a result of hydrogen bonding - extra heat must be used to disrupt the bonds.

Without these bonds water would boil at about -80 degrees Celsius. The attractive forces in steam are much weaker than those of liquid water.

The molecules move more quickly than in liquid water, are widely separated and they can move around in any direction.





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