1. Qualitative analysis – the identification of the specific substances present
Quantitative analysis – the measurement of the quantity of a substance present

2. Qualitative Analysis
Many substances can be identified by their unique physical or chemical properties:
Observation of colour of solution
For cations that are usually colourless in solution and highly soluble, a flame test may be used (only works when a single cation is present)
For gases, perform a gas test to identify if the gas produced is H2, O2, or CO2
Other possible qualitative tests
Reactions with other substances to produce a new colour and/or precipitate

3. 1. Qualitative Analysis – Colour of Solution

4. 2. Qualitative Analysis – Flame Test
The majority of solids are white powders and difficult to distinguish between just by looking.
Flame tests can give a good indication of what metal ion it contains.

6. 3. Qualitative Analysis – Gas Test
Most gases are clear, colourless and odourless. 
So it's not easy to distinguish between them with a simple chemical test.

7. Test for Hydrogen
Hydrogen is less dense than air and explosive when mixed with Oxygen.
A test-tube filled with hydrogen can be safely held up-turned since no Hydrogen can escape by sinking into denser air.

9. Oxygen Test
Oxygen has a similar density to air, so needs to be contained in a "right-side up" container
So, if we light a splint and blow out the flame so that the end is still glowing (the reason the flame does not reappear is that 79% of the air around it is not Oxygen)
Placing the glowing splint in pure Oxygen means that every gas molecule that collides with the glowing ember is Oxygen.
This increases the rate of reaction, providing enough heat to re-light the flame. 

11. Carbon Dioxide Test
Carbon Dioxide puts out fires. But so do most other gases.
So the test for Carbon Dioxide must be something that only Carbon Dioxide does.
Only Carbon Dioxide turns Lime-water milky white
The white colour is a precipitate of Calcium Carbonate ( like chalk).

13. 4. Other possible tests
Conductivity – to determine if solution is ionic or covalently bonded
pH – to determine id the solution is acidic or basic
Universal indicator (neutral is green, red is acid, blue is base)
Bromothymol blue (neutral is green, yellow is acid, blue is base)
Phenolphthalein (pink is base)

14. Melting point/boiling point
Solubility in water – to determine polar or non polar

15. 5. Qualitative Analysis – Reactions in Solution
This is a type of test where we set up a double displacement reaction using one unknown solution and one known solution
In this test, we would predict that if a precipitate forms then a certain ion must have been present in the unknown solution

16. Indicate the test being performed
Identify a Positive Test
What Observations did you see?
Analysis – what does this mean?
Identify a Negative Test

17. To Complete A Sequential Analysis
Locate the possible cations on the solubility table.
Determine which anions would precipitate the possible cations.
Plan a sequence of precipitation reactions that would use anions to precipitate a single cation at a time.
Use filtration between the steps to remove cation precipitates that might interfere with subsequent additions of anions.
Draw a flow chart to assist testing & communication.

18. Example 1 No Lead (II) ions present A solution known to contain Pb2+
Positive test is a white precipitate
Solution contained Lead(II) ions, precipitated as PbCl2
Negative test is no precipitate
No Lead (II) ions present
Add NaCl

19. Example 2 A solution known to contain Sr2+
Positive test is a white precipitate
Solution contained Sr2+ ions, precipitated as SrSO4
Negative test is no precipitate
No Sr2+ ions present
Add Na2SO4

20. Example 3 A solution known to contain Cu2+
Positive test is a white precipitate
Solution contained Copper (II) ions, precipitated as Cu(OH)2
Negative test is no precipitate
No Copper (II) ions present
Add NaOH

21. To Complete A Sequential Analysis
Locate the possible cations on the solubility table.
Determine which anions would precipitate the possible cations.
Plan a sequence of precipitation reactions that would use anions to precipitate a single cation at a time.
Use filtration between the steps to remove cation precipitates that might interfere with subsequent additions of anions.
Draw a flow chart to assist testing & communication.

22. You try!
Design a sequential analysis for each of the ions below, to determine if it is present in the solution.
Ag+
Ca2+
Mg2+

23. Example with Two Ions
A solution is thought to contain lead (II) ion or magnesium ion. Design a sequential qualitative analysis to determine whether the solution contains either or both of these ions

24. Solution known to contain Pb2+ (aq) or Mg2+ (aq)
If Solution contains Pb2+ ions, a ppt will form of PbCl2
Solution contained Pb2+ ions, precipitated as PbCl2
If Solution does not contain Pb2+ ions then no ppt will form
No Lead (II) ions present
Add NaCl – the Na+ is always soluble, the Cl- will ppt with Pb2+, the Cl- is soluble with Mg2+

25. If a positive test occurred, filter off the ppt and run a second test for the second cation

26. If a white ppt forms, the Mg2+ ions present in form if MgCO3
Add Na2CO3 – again, Na+ is always soluble, but the CO32- will ppt with Mg2+
If a white ppt forms, the Mg2+ ions present in form if MgCO3
If no ppt forms then no Mg2+ was present

27. Another Example with Two Ions
A solution is thought to contain calcium ion and mercury (II) ion. Design a sequential qualitative analysis to determine whether the solution contains either or both of these ions

28. Solution known to contain Ca2+ (aq) or Hg2+ (aq)
If Solution contains Hg2+ ions, a ppt will form of HgCl2
Solution contained Hg2+ ions, precipitated as HgCl2
If Solution does not contain Hg2+ ions then no ppt will form
No Hg2+ ions present
Add NaCl – the Na+ is always soluble, the Cl- will ppt with Hg2+, the Cl- is soluble with Ca2+

29. If a positive test occurred, filter off the ppt and run a second test for the second cation

30. If a white ppt forms, the Ca2+ ions present
Add Na2SO4 – again, Na+ is always soluble, but the SO42- will ppt with Ca2+
If a white ppt forms, the Ca2+ ions present
If no ppt forms then no Ca2+ was present

31. You Try!!
Design a sequential analysis for each of the pairs of ions below, to determine if one or both are present in the solution.
Ba2+ and Pb2+
Ag+ and Zn2+
Sr2+ and Mn2+
Cu+ and Fe3+

32. Example containing three ions!
Solution known to contain Ag+1aq or Cu2+aq or Ba2+ ion
Chose an anion that will produce a ppt for one of the cations
Add NaCl – the Na+ is always soluble, but the Cl- will ppt with Ag1+
If Solution contains Ag1+ ions, a ppt will form of AgCl
If Solution does not contain Ag1+ ions then no ppt will form

33. If a positive test occurred, filter off the ppt and run a second test for the second cation

34. If a ppt forms, the Cu2+ ions present in the form of Cu(OH)2
Add NaOH – This causes basic conditions and OH- ion will ppt with Cu2+ (Ba2+ is soluble with OH-)
If a ppt forms, the Cu2+ ions present in the form of Cu(OH)2
If no ppt forms then no Cu2+ was present

35. If a positive test occurred, filter off the ppt and run a third test for the third cation

36. Add Na2SO4 –Na+ is always soluble and Ba2+ ion will ppt with SO42- ion
If a ppt forms, the Ba2+ ion present
If no ppt forms then no Ba2+ was present

37. You should perform the colour of solution test and the PPT tests to narrow down which ions you think are present.
You should also determine the colours that each ion would produce in a flame test before performing the flame test
The flame test is not used to confirm or eliminate the presence of a particular ion.