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Qualitative Analysis (4C): A Foundation for Lab Skills

Qualitative Analysis (4C): A Foundation for Lab Skills. Concept Presentation Tuesday, July 13, 2010 C. Burt. Presentation Outline. Introduction Curriculum Expectations Student Demographic Instructional Approaches Misconceptions Textbook Issues Assessment & Evaluation References.

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Qualitative Analysis (4C): A Foundation for Lab Skills

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  1. Qualitative Analysis (4C):A Foundation for Lab Skills Concept Presentation Tuesday, July 13, 2010 C. Burt

  2. Presentation Outline • Introduction • Curriculum Expectations • Student Demographic • Instructional Approaches • Misconceptions • Textbook Issues • Assessment & Evaluation • References

  3. What is Qualitative Analysis?

  4. Qualitative Analysis http://jchemed.chem.wisc.edu/JCESoft/CCA/CCA3/STILLS/FEZNSUL/FEZNSULF/64JPG48/6.JPG http://edu.glogster.com/media/1/9/42/67/9426718.jpg http://www.gettyimages.ca/detail/200448588-001/Riser?language=en-US&location=CAN

  5. Curriculum Expectations B2.3 investigate precipitation reactions and flame tests, using qualitative analysis instruments, equipment and techniques [PR, AI] B2.4 conduct qualitative analysis of an unknown sample, using a flow chart and experimental procedures, including flame tests and precipitation reactions to determine the presence of metal ions [PR, AI] B2.5 identify an unknown gas sample by observing its emission spectrum and comparing it to the spectra of known gases [PR, AI]

  6. What does it look like? http://gabudjr.files.wordpress.com/2009/11/flammes_colorees_petit.jpg http://staff.norman.k12.ok.us/~cyohn/index_files/ddlab_files/image001.jpg

  7. What does it look like? http://www.physics.umd.edu/courses/Phys401/bedaque07/discrete_spectra.jpg

  8. Who are the Students? SNC2D Grade 10, Academic SCH4C Grade 12, College SNC2P Grade 10, Applied

  9. Why is it important? Forensics • identification of unknown materials • association of unknowns to potential sources Fireworks • production of colourful pyrotechnic displays for entertainment purposes Food/Water Quality Analysis • contamination recognition • toxicity testing Astronomy • indirect identification of atoms on celestial objects

  10. Instructional Approaches

  11. Course Context • Matter & Qualitative Analysis = first unit of SCH4C • review the periodic table, symbols and atomic theories • foundation for the remainder of the course (Shamai and Stavy, 1986) • develop good lab skills

  12. Proposed Sequence – Lesson #1 • Review physical properties of matter • Relate unique chemical structure to qualitative properties • examine solids and solutions • Introduce the flame test as a qualitative technique • compare solution colours to flame colours • demonstrate technique for lab • disclose what they need to show for evaluation

  13. Misconceptions • impossible to differentiate between white powders • colour of solid and solution is identical or similar to that of the flame test colour

  14. Demo / Display #1

  15. Textbook Tables Solution Colour Flame Colour Chemistry 11, McGraw-Hill Text

  16. Remake the Tables! • have the students make the tables • encourage good lab skills • allow them to test multiple times http://www.cwcompliance.com/whmis_flammable.jpg

  17. Proposed Sequence – Lesson #2 • Pre-lab preparation • Conduct lab • students generate their own tables • Practice assessment • students use their generated tables with unknown samples • can self-assess whether their tables were poor or helpful • test household solutions

  18. Proposed Sequence – Lesson #3 • Introduce precipitate formation as a qualitative technique • demo #2

  19. Demo #2

  20. Proposed Sequence – Lesson #3 • Introduce precipitate formation as a qualitative technique • demo #2 • Review terms (soluble, insoluble, aqueous) • Demonstrate how to read solubility tables • Experiment with various dropper bottles and spot plates • allow students time to see reactions and associate solubility table

  21. Textbook Table – Example #1 http://castlelearning.com/review/reference/chem%20table%20f.gif

  22. Textbook Table – Example #2 http://www.professormeyer.com/images/solubility%20chart.jpg

  23. Textbook Table – Example #3 Cations

  24. Solubility Song

  25. Evaluation • Standard pen & paper test (I) • Practical test (K / I) • Make a fire log which burns in a specific colour sequence. (A) • Identification of ions in drinking water (I) http://image09.webshots.com/9/8/54/94/111785494sGJSSV_fs.jpg

  26. References • Ministry Documents – Grade 11 and 12 Science • Shamai, R. and Stavy, R., Teaching an Introductory Course in Qualitative Analysis in Order to Enhance Learning General Chemistry, J. Chem. Educ., 1986, 63 (8), p 707 • Chemistry 12 College Preparation, Nelson Text, 2004 • Chemistry 11, McGraw-Hill Text, 2001 • www.otfchemistry.webs.com

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