Chemistry 4.6 Flashcards
Test for hydrogen
Lit split produces a squeaky pop
Test for oxygen
Relights a glowing splint
Test for carbon dioxide
Bubble gas through limewater, turns cloudy
Test for chlorine
Bleaches damp blue litmus paper white
Describe the flame test
Dip wire loop in HCl and place in roaring flame until no more colour is observed
Dip wire loop in sample and then into roaring flame.
Observe colour
Flame test result for Lithium (Li+)
Red flame
Flame test result for Sodium (Na+)
Yellow flame
Flame test result for Potassium (K+)
Lilac flame
Flame test result for Calcium (Ca2+)
Orange-red flame
Flame test result for Copper (Cu2+)
Blue-green flame
Test for Iron (II) Fe2+
Add NaOH. Green precipitate forms
Test for Iron (III) Fe3+
Add NaOH. Orange-brown precipitate forms
Test for Copper (Cu2+)
not flame test
Add NaOH. Blue precipitate forms
Test for ammonia
Turns damp red litmus paper blue
Test for NH4+ (Ammonium)
Add NaOH (and warm). Ammonia gas is produced which turns damp red litmus paper blue.
Test for CO32- carbonate
Add HCl. Fizzing appears –> bubble gas through limewater and it will go cloudy
Test for SO42- sulphate
Add acidifed barium chloride (BaCl2). White precipitate will formed.
Test for Cl- chlorine
Add nitric acid followed by AgNO3 (acidified silver nitrate). White precipitate will form.
Test for Br- bromine
Add nitric acid followed by AgNO3 (acidified silver nitrate). Cream precipitate will form.
Test for I- iodine
Add nitric acid followed by AgNO3 (acidified silver nitrate). Yellow precipitate will form.
How to remember results (colour of precipitates) for halide ions
Milk - white
Cream - cream
Cheese - yellow
You’re testing a solid using sodium hydroxide, what must you do first?
Dissolve the solid in water.
How would you calculate the Rf value of an ink on chromatography?
Distance moved by spot/distance moved by solvent
Define cation
A positively charged ion
Define anion
A negatively charged ion
