Lecture Free Teaching: Properties of Solutions

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Lecture Free Teaching: Properties of Solutions

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1. Lecture Free Teaching: Properties of Solutions 2010 KSTA Conference Lisa Devillez Marshall County High School

2. Lecture Free Teaching (LFT) • Note-making as “homework” / Vodcasting foundational lectures • improves textbook reading skills • classroom discussion focused on student questions • more class time for labs • more time for "advanced" problems • Active Learning!

3. Lecture Free Teaching (LFT) • Clear and concise objectives • Notes • Homework • Tests • Mastery learning & standards-based grading are complementary LFT

4. Lecture Free Teaching (LFT) • Class time • Opportunity for student feedback • Collection of active learning activities • Limit “lectures” (ie., passive instruction) in both frequency and time

5. Solutions • The perfect “unit” for LFT and developing lab skills • Narrowed scope of objectives based on difficulties of former students • Selected / modified labs to address all of the objectives

6. Objectives • 5.1 Define units of concentration, mass percent, ppm, mole fraction, molarity, and molality, and be able to calculate each from appropriate data. • 5.2 Be able to convert a concentration from one unit to the other. • 5.3 Be able to calculate solution concentration for single and serial dilutions. • 5.4 Describe the effect of solute (or solvent) concentration on boiling point and freezing point. Be able to calculate any of these effects from concentration data for nonelectrolyte solutes.

7. The Labs: General Format • Prepare a solution of the assigned concentration. • Measure property for 5 standard solutions (teacher-prepared) and student solution. • Graph property vs. concentration for the standards • Use equation for trend line and measurement for student solution to verify its concentration

8. The Labs: Documentation • Data Tables • Standards graphs • Trend line • Correlation value (R2) • Calculations • Verification of student solution concentration • % error

9. Glucose Standards

10. Glucose Standards

11. Hydrometry : Specific gravity

12. Refractometry: Snell’s Law “The determination of the concentrations of sugar solutions by Laser Refractometry” Hughes & Jelks JCE November 1988

13. Refractometry: Snell’s Law

14. Colligative Properties: Freezing point • Assigned 2.0M 100mL • Standards in molalities

15. Spectroscopy: Beer’s Law • 5mL glucose solution & 5mL Benedict’s • Spec 20; 730nm; distilled water blank

16. Calibration Curves

17. Calibration Curves