day 13 - qa and flame test lab - algonquin &...
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Day 13 QA and Flame Test Lab
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What is it?
The process of separating and identifying ions in an aqueous solution.
Why is it done? • to test the purity of products, such as drinking water• in crime detection laboratories• in medical testing, blood and urine analysis
There are many different techniques in qualitative analysis, we will use three. 1
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colour of solution
selective precipitationflame test
Qualitative Analysis
1) Solution Colour
Limitationsmost solutions are colourlesssome ions produce the same colours
Some ions produce a distinct colour in solution.
See p.344 for a list of the most common.
Day 13 QA and Flame Test Lab
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Ex. You have a solution that might contain Mg2+ or Ca2+ a) What solution could you add to find out if Mg2+ is present?
b) What solution could you add to find out if Ca2+ is present?
Limitationssome ions precipitate more than one ionex. some ions will never precipitateex. NO3 K+, Na+, NH4+
Use your Solubility Table!!!
Mg2+ is present
Mg2+ not presentMg2+ or Ca2+
Add ppt forms
no ppt
Ca2+ is present
Ca2+ not presentAdd ppt forms
no ppt
Ni+2 or Ca2+
2) Selective Precipitation A solution known to precipitate a certain ion is added. If a precipitate results, the ion is present, if there is no precipitate, the ion is not present.
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3) Flame TestMany ions give off a distinct colour when placed in a Bunsen burner flame.
Limitations colour intensity varies widely sometimes hard to see impurities can affect results not all ions show a distinctive colour
Try the Flame Test Activity!!!
nichrome wire
Day 13 QA and Flame Test Lab
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