Chemical Tests Flashcards
(26 cards)
Test for hydrogen gas
Gives off squeaky pop with lit splint.
Test for oxygen gas
Relights a glowing splint
Test for carbon dioxide
Bubble the gas through lime water (calcium hydroxide). Limewater turns white/cloudy/milky.
Test for ammonia gas
Damp red litmus paper turns blue
Test for chlorine gas
Damp blue litmus paper turns red then is bleached white
What are flame tests used for?
Flame tests are used to identify metal ions
Flame test for lithium
Red
Flame test for sodium
Yellow
Flame test for potassium
Lilac
Flame test for calcium
Orange-red
Flame test for copper
Blue-green
Test for ammonium ions
Add sodium hydroxide and warm, ammonia gas is produced and turns damp red litmus paper blue.
What colour precipitate is formed when NaOH is added to a solution containing Cu2+ ions?
Blue
What colour precipitate is formed when NaOH is added to a solution containing Fe2+ ions?
Green
What colour precipitate is formed when NaOH is added to a solution containing Fe3+ ions?
Brown
Test for chloride ions
Add nitric acid and silver nitrate solution (AgNO3). A white precipitate (AgCl) is formed.
Test for bromide ions
Add nitric acid and silver nitrate solution (AgNO3). A cream precipitate (AgBr) is formed.
Test for iodide ions
Add nitric acid and silver nitrate solution (AgNO3). A yellow precipitate (AgI) is formed.
Test for sulfate ions SO₄²⁻
Add dilute hydrochloric acid, add drops of barium chloride solution.
Test result for sulfate ions
White precipitate of barium sulfate
Test for carbonate ions
Add dilute HCl. Fizzing is observed as carbon dioxide gas is released which turns limewater white/cloudy/milky.
Chemical test for water
Anhydrous copper sulfate is added to liquid, if it goes from white to blue, it will be water
Physical test for water
Boil the liquid and measure it’s boiling point. If it boils at 100C it is water
Why is nichrome wire used in a flame test?
Inert (unreactive) so will not affect the colour of the flame and has a high melting point.
