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Essential Science for Teachers: Physical Science

Physical Changes and Conservation of Matter Interactive Activity: Virtual Particle Lab

Virtual Particle Lab: Dissolving

During Session 3, one of the physical changes we examined was dissolving, particularly dissolving salt in water. The biggest question we faced was, “Does the salt disappear and, if not, where does it go?” The principle of conservation of mass tells us that no particles are lost, but how can we explain the fact that we no longer see the salt in the bottom of the beaker of water from a particle point of view?

In this lab, you’ll experiment with a realistic microscopic model of one substance dissolving in another. You’ll discover that the relative strength of the forces between particles is the key to understanding this macroscopic phenomenon.

Exploring the Model

The following is a simulation of one material dissolving into another material. The substance we would like to have dissolved — the solute — is shown in blue.

The particles that are shown as spheres could be atoms, molecules, or something more complex, depending on the substance we are trying to represent. Note that solutes do not always have to be solids — a liquid can be dissolved into a liquid (for example, at the end of Session 3, we dissolved alcohol into water).

The substance in which we want to dissolve the solute — the solvent — is shown in red. Again, these particles could be atoms, molecules, or something more complex, depending on what substance we are trying to represent.

 

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Series Directory

Essential Science for Teachers: Physical Science

Credits

Produced by Harvard-Smithsonian Center for Astrophysics. 2004.
  • Closed Captioning
  • ISBN: 1-57680-749-5

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