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

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

3. What is Qualitative Analysis?

4. Qualitative Analysis

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?

7. What does it look like?

8. Who are the Students? SNC2D Grade 10, Academic SCH4C Grade 12, College
Discuss what they should know
SNC2P
Grade 10, Applied

9. Why is it important? Forensics Fireworks Food/Water Quality Analysis
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. impossible to differentiate between white powders
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 Flame Colour Solution Colour Ion Symbol Colour lithium
red
sodium
Na+
yellow
potassium K+
violet
cesium
Cs+
calcium
Ca2+
strontium
Sr2+
barium
Ba2+
yellowish-green
copper
Cu2+
bluish-green
boron
B2+
green
lead
Pb2+
bluish-white
Solution Colour
Ions
Symbol
Colour
chromium (II)
copper (II)
Cr2+
Cu2+
blue
chromium (III)
copper (I)
iron (II)
nickel (II)
Cr3+
Cu+
Fe2+
Ni2+
green
iron (III)
Fe3+
pale yellow
cobalt (II)
manganese (II)
Co2+
Mn2+
pink
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
Ions
Symbol
Colour
chromium (II)
copper (II)
Cr2+
Cu2+
blue
chromium (III)
copper (I)
iron (II)
nickel (II)
Cr3+
Cu+
Fe2+
Ni2+
green
iron (III)
Fe3+
pale yellow
cobalt (II)
manganese (II)
Co2+
Mn2+
pink

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

22. Textbook Table – Example #2

23. Textbook Table – Example #3
Anions
Cl-
Br- I-
S2-
OH-
SO42-
CO32-
PO43-
SO32-
C2H3O2-
NO3-
High
Solubility (aq)
≥ 0.1 mol/L
(at SATP)
most
Group 1
Group 2
NH4+
Sr2+
Ba2+
Tl+
all
All Group 1 compounds, including acids, and all ammonium (NH4+) compounds are assumed to have high solubility in water.
Low solubility (s)
< 0.1 mol/L (at SATP)
Ag+
Pb2+
Hg22+
(Hg+)
Cu+
Ca2+
Ra2+
none
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)

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