Objectives
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Students will: discriminate solutions from other mixtures (ex. Suspension),
demonstrate water's ability to dissolve in solids, liquids and gases
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Standards Addressed
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Minnesota Graduate Standards: Middle Level: Physical Science |
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(Prep): 1) Project WET guide; 2) Copies of a) "Case of the Missing Coin Collection, Part I" p 57-58, b) "Case of the Missing Coin Collection Part II" p 60 and c) Solution Investigation Guide, p 59; 3) baby food jar, lid labeled "A" (sugar and water); 4) baby food jar, lid labeled "B" (sand and water); 5) two 100 ml graduated cylinders; 6) water; 7) rubbing alcohol; 8)vegetable oil; 9) two balloons; 10) three bottles 7-Up or Sprite: one chilled in ice water; one heated in hot water; one left alone; and 11) chilled water
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Time Requirement
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Prep time: one hour
Activity: one 50-minute class period |
Procedure/ Outline
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1.
Define SOLUTION. List examples of solutions we use/consume daily/often.
2.
Using background information on p 54-55 of Project WET guide, help students understand why water is the UNIVERSAL SOLVENT. Explain and show why water is abbreviated H20 and how the (+) and (-) attractions of IONS help make solutions in water.
3.
Explain and give examples of how water can dissolve liquids, solids and gases.
4.
Have students read Part 1 of the mystery; have them look for clues in the story and underling them. Discuss.
5.
Hand out the Solution Investigation sheet, complete the experiments as demonstrations or in small groups and discuss. How do these activities help us with the mystery?*
6.
Have students read Part 2 of the mystery. Do we keep soda in the refrigerator to JUST keep it cold? (NO!) It keeps the carbonation (DISSOLVED CO2) in the soda for a longer period of time
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Modifications /Adaptions/ Extensions
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1.
Discuss that solutions may be a part of the water we drink. Are they GOOD or BAD? How can we keep what we want and get rid of the rest? (water treatment plant connection).
2.
Show that SUPER-saturated solutions (NaCl) may be DENSER than less-saturated solutions. Mix different concentrations of NaCl solution and make them different colors - you have to use canning/pickling salt or it WON'T work! You can layer them in a beaker or glass tube to show that less-dense solutions can "float" on more dense solutions. Show different solutions and suspensions from the activity. Which of these are SOLUTIONS and WHY? What is one thing from the mystery that helps keep gas in a solution?
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Assessment
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QUIZ TIME!! What is a solution? What is one reason why water is the UNIVERSAL
SOLVENT?
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Other Comments
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The demonstration of the activities with student helpers is less expensive and
saves time. Students will need to be led into the soda connection - ask them
about each area in the room for help |
