Activity

Summary

In this inquiry activity, students investigate types of solutions, identifying the solute and solvent, and classifying each solution.  They them solve stoichiometry problems involving solutions of different concentrations.

Grade Level

High school

Objectives

By the end of this lesson, students should be able to

• identify the solute and solvent in a solution.
• perform stoichiometric calculations involving solutions.
• classify solutions.
• define terms related to solutions.

Chemistry Topics

This lesson supports students’ understanding of

• Solutions
• Solute
• Solvent
• Stoichiometry
• Tyndall effect
• Molarity

Time

Teacher Preparation: 30 minutes

Lesson: 45 minutes

Materials

For each group:

• Beakers filled with each of the following:
  • Bromothymol Blue in water
  • Milk in water
  • Oil in water
• Baking soda
• Straw
• Flashlight
• Safety goggles

Safety

• Always wear safety goggles when working with chemicals in a laboratory setting.
• Be sure to not inhale any liquid through the straw.
• Students should wash their hands thoroughly before leaving the lab.
• When students complete the lab, instruct them how to clean up their materials and dispose of any chemicals.

Teacher Notes

• Have the students complete the solution activity before completing the stoichiometry worksheet.
• Students should be familiar with how to solve stoichiometry problems before completing this activity.
• Students should be familiar with the concepts of molarity before completing this activity.

Downloads

• Teacher Guide.doc
• Teacher Guide.pdf
• Student Activity.doc
• Student Activity.pdf
  

Submitted by
Kathy Teski
Milford High School
Milford, Ohio

Thanks to
PASCO

For the Student

Lesson

Materials

• Beakers filled with each of the following:
  • Bromothymol Blue in water
  • Milk in water
  • Oil in water
• Baking soda
• Straw
• Flashlight

Bromothymol Blue in water:

What was the solute? _________________  What was the solvent? ____________

Is this a solution? _____ Why? ______________________________________

_________________________________________________________________

Blow bubbles into the beaker of blue water used above:

What was the solute? _________________  What was the solvent? ____________

Why did the color change from blue to yellow? _____________________________

__________________________________________________________________

Is this a solution? _____  Why ? ____________________________________________

__________________________________________________________________

Now add baking soda into the beaker of water used above:

What was the solute? _________________  What was the solvent? ___________

Why did the color change from yellow to blue? ___________________________

_________________________________________________________________

Is this a solution? _____ Why ? ___________________________________

_________________________________________________________________

Milk in Water:

What was the solute? ________________  What was the solvent? ____________

Now shine a light into the beaker.  What did the light show in the beaker of liquids? __________________________________________________________________

_________________________________________________________________

Is this a solution? _____ Why ? _________________________________

_________________________________________________________________

How is it classified? _______________________________________

Oil in Water:

What was the solute? _________________  What was the solvent? ___________

Is this a solution? _____ Why ? ______________________________________

_________________________________________________________________

How is it classified? _______________________________________

Work in groups to develop definitions of the following terms.  Provide an everyday example of each in the second column.  Use your own words, though you may consult references.

                             Term Defined                                               Everyday Example

Solute:

Solvent:

Concentrated:

Dilute:

Suspension:

Colloid:

Solution:

Dissolving:

Tyndall Effect:

Electrolyte:

Precipitate

Saturated:

Unsaturated:

Stoichiometry with Solutions

Each of the following problems has the correct answer given. Determine how each of these problems was solved.

2 NaOH (s)   +   FeCl₂ (aq)   ⇾  Fe(OH)₂ (s)   +   2 NaCl (aq)

1.   100.0 g sodium hydroxide reacts in stoichiometric proportions with what volume of 0.500M iron(II) chloride solution?  (2.50 L)

2.   100.0 ml of 0.500 M iron(II) chloride solution reacts with excess sodium hydroxide to produce what mass of iron(II) hydroxide as a precipitate. (4.49 g)

3 AgNO₃ (s) + Ni(CH₃COO)₃ (aq)  ⇾  3 AgCH₃COO (s) +  Ni(NO₃)₃ (aq)

3.   What volume of 0.100M nickel(III) nitrate can be produced from the reaction of 100.0 g silver nitrate with excess nickel(III) acetate? (1.96 L)

4.   What mass of silver acetate precipitate would be produced from the reaction to 250.0 ml of 0.250M nickel(III) acetate and excess silver nitrate? (31.3 g)

5.   What concentration nickel(III) nitrate would be produced from the reaction of 250.0 mL of 0.250M nickel(III) acetate and excess silver nitrate? (0.250 M)

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