Chemical Tests Flashcards
Define Cation
Positive
Define anion
Negatives
What colour flame does Li+ create
Red
What colour flame does Ca+2 create
Orange
What colour flame does Na+ create
Yellow
What colour flame does Cu+2 create
Green
What colour flame does K+ create
Lilac
Describe a flame test
- dip nichrome wire into hydrochloric acid (to clean it so we can only see the colour of the sample and so the sample sticks to it)
- dip wire into sample
- place wire into blue Bunsen burner flame
Test for hydrogen
Lit splint in gas goes out with a squeaky pop
Because hydrogen and oxygen react to create water, and it creates a squeaky pop as the gas is forced out of the containter
Test for oxygen
Glowing splint in gas relights
Because the oxygen, splint and heat create fire
Chemical test for water
Add to white anhydrous copper sulphate turns blue (hydrated copper sulphate)
Test for water (purity test)
Boil - it should boil at 100 degrees not over a range of temperatures
Test for carbon dioxide
Bubbled through limewater turns cloudy
Test for chlorine
Damp (chlorine can diffuse into it) litmus paper in gas is bleached white
Test for ammonia
Damp red litmus paper turns blue
Because OH- is produced (alkaline/base)
Describe a hydroxide test
Dissolve sample in distilled water
Add sample to test tube
Add NaOH to tube
Hydroxide tests
What colour precipitate does Cu +2 form
Blue
Hydroxide tests
What colour precipitate does Fe +2 form
Green
Hydroxide tests
What colour precipitate does Fe +3 form
Brown
Describe a halide test
- dissolve sample into distilled water if solid
- add few drops of sample to test tube
- add nitric acid (HNO3)
- add few drops of silver nitrate
Halide tests
What precipitate is formed from Chloride
White
Halide tests
What precipitate is formed from bromide
Cream
Halide tests
What precipitate is formed from iodide
Yellow
Test for carbonate (CO3 -2)
Add hydrochloric acid
Fizzing = bubble gas through limewater which should turn cloudy if carbonate is present
Test for Sulphate (SO4 -2)
Add hydrochloric acid
No fizzing = add Barium Chloride (BaCl2) = white precipitate formed
Which anion test is used to test for I2, Cl2, Br2
Halide tests
Dissolve sample in distilled water if solid
Add sample and nitric acid to test tube
Add silver nitrate
Observe colour of precipitate formed
What cation test is used to test for Cu +2, Fe +2, Fe +3?
Hydroxide test
Dissolve sample in distilled water if it’s a solid
Add sample to test tube
Add NaOH and observe
What cation test is used to test for:
Li +1
Na +1
K +1
Ca +2
Cu +2
Flame tests
Dip nichrome wire in hydrochloric acid
Dip wire into solid
Place wire into blue Bunsen burner flame and observe colour
