Dissolving Salt

Studetns observe whapt happens to salt when mixed with water and what occurs as the water evaportes.  Students watch and measure the amount of water that has evaporated over the course of time.  The students will also see that after the water has evaporated that the salt is still in the bottom of the cup.  This lesson plan also has PDF files of the procedures for each group and a lab journal page for recording their results. It has rubrics for the journal page and participation. You could also use this in a mixtures lab.

Weblink address (URL): 
Dissolving Salt

Standards & Objectives

Essential and guiding questions: 
  • How does the weight of the cup after the water evaporated compare with the weight of the cup and the salt before the water was added? Explain why.
  • What is the material in the cup?
  • Was your prediction correct?
  • When the salt dissolved in the water, was it a chemical reaction or a physical change? How do you know? (It was a physical change because all of the salt was still there when the water vaporated. There were no new substances formed.)

Lesson Variations

Blooms taxonomy level: 
Understanding
Extension suggestions: 

Extensions:

  • You may want to consider having part of the class do this activity using sugar or baking soda. Then allow the teams to compare data at the completion of the procedures.

Helpful Hints

Materials:

  • For each team:
  • clear plastic cup
  • scale
  • table salt
  • plastic spoon for stirring
  • measuring spoon

References

Contributors: 
Christine Gillum
Originator: 
Ayers Institute for Learning & Innovation