4.6 Chemical Analysis
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How do you conduct a flame test
Dip platinum wire into hydrochloric acid dip wire into a sample of solid or solution Place tip of wire into non-luminous Bunsen burner
What colour is Lithium’s flam e
Red
What Colour is Sodium’s flame (Na)
Yellow
What colour is Potassium flame (k)
Lilac
what colour is Ca (Calcium) flame
Orange-Red
What colour is Cu flame ( copper)
Blue- Green
How do you conduct a sodium Hydroxide test
Dissolve sample in water add a few drops of sodium hydroxide
What colour precipitate is Fe2+(sodium hydroxide)
Green Fe(OH)2
What colour precipitate is Fe3+ (sodium Hydroxide)
Brown Fe(OH)3
what colour precipitate is Cu2+ (sodium hydroxide)
Blue Cu(OH)2
What is the test for Ammonium test
Dissolve sample in water Add sodium hydroxide and warm it Test gas evolved with damp red litmus paper
What is a positive Ammonium test
Turns damp red litmus paper to blue
How do you test for halides
Dissolve the sample in water Add nitric acid Add silver nitrate solution
What colour is Cl - precipitate and its’ formular (for a halides test)
White AgCl
What colour is Br - precipitate
Cream AgBr
What colour is I- precipitate for a halide test
Yellow AgI
How do you carry out the test for Carbonates
Add hydrochloric acid If there is effervescence, bubble gas through limewater turns cloudy if carbonate
Describe the test for sulphates
Add Hydrochloric acid If there is no effervescences add barium chloride forms a white percipitate
What is the colour of the precipitate for barium Chloride
White precipitate
Why is it important to check if there is no effervensence
to prevent false positives Carbonate ions also forms a white precipitate