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Chapter 2, Lesson 2 Multimedia

Evaporation

An animation demonstrating that hot water evaporates more quickly than cold water.

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  • Heating the water on the paper towel increases the motion of the water molecules.
  • When the molecules have enough energy, they can move fast enough to break away from the attractions holding them to other molecules.

Heating and Evaporation

A ziploc bag filled with hot water with a wet paper towel on top.  With this setup, water evaporates from the paper towel more quickly.A ziploc bag filled with room temperature water with a wet paper towel on top.  With this setup, water evaporates from the paper towel more slowly.

Compare the number of motion lines and the spacing of the water molecules in the water on each paper towel. Heated water molecules have more energy and move faster than the room temperature water molecules. These faster moving molecules are able to overcome the attractions they have for other water molecules more easily and evaporate.

Models of Water Molecules

Several different representations of a water molecule: ball and stick and space-filling.

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  • The ball-and-stick model shows that atoms are bonded at certain angles in the molecule.
  • The space-filling model shows the region taken up by the electron clouds of the atoms in the molecule.

Liquid Water

An animation demonstrating the behavior of liquid water at the molecular level. Many molecules of water intereact with each other, but can slide past one another.

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The molecules in liquid water are attracted to one another but are able to slide past each other. If you look closely, you can see some molecules where the hydrogen atoms of one molecule are “bonded” to the oxygen of another. This video appears courtesy of Roy Tasker.
© Roy Tasker, VisChem Project.

Water Vapor

An animation showing water vapor at the molecular level. Water molecules in the gas phase are much further apart than they are in the liquid phase.

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  • Molecules are very far apart. After evaporating, the molecules of water vapor has separated from the molecules in the liquid water.
  • The molecule itself does not break apart into individual atoms. This video appears courtesy of Roy Tasker.
    © Roy Tasker, VisChem Project.