Testing for Cations, Anions and Gases Flashcards
What colour does Lithium burn with in a roaring Bunsen flame?
Red
What colour does Sodium burn with in a roaring Bunsen flame?
Yellow
What colour does Potassium burn with in a roaring Bunsen flame?
lilac
What colour does Calcium burn with in a roaring Bunsen flame?
orange-red
What colour does copper burn with in a roaring Bunsen flame?
blue-green
If you add NaOH (Sodium Hydroxide) to Copper (II), Cu2+, what colour is the precipitate?
Blue
If you add NaOH (Sodium Hydroxide) to Iron (II), Fe2+, what colour is the precipitate?
Sludgy green
If you add NaOH (Sodium Hydroxide) to Iron (III), Fe3+, what colour is the precipitate?
Reddish Brown
How do you test whether a substance contains ammonium ions (NH4+)
Add some NaOH (Sodium Hydroxide) to the mystery substance. If a gas is given off which turns damp red litmus paper blue then ammonia is present. It also smells of cats wee!
How do you test for Ammonia Gas?
Damp red litmus paper, if ammonia present the paper will turn blue
How can you test for carbonates?
Add Hydrochloric Acid to the potential carbonate. if carbonates are present then CO2 gas will be given off which turns Limewater milky and the carbonate will effervesce
How can you test for sulphates?
Add dilute Hydrochloric Acid and then barium chloride to the compound. If a white precipitate is formed (Barium Sulphate), the original compound was a sulphate
How do you test for a chloride ion?
Add dilute Nitric Acid followed by Silver Nitrate solution. If there is a chloride ion a white precipitate of Silver Chloride will be formed
How do you test for a bromide ion?
dd dilute Nitric Acid followed by Silver Nitrate solution. If there is a bromide ion a cream precipitate of Silver Bromide will be formed
How do you test for a iodide ion?
dd dilute Nitric Acid followed by Silver Nitrate solution. If there is a iodide ion a yellow precipitate of Silver Iodide will be formed
Why do you add the nitric acid when testing for a halide?
To get rid of carbonate or sulfate ions before the test
How do you test for chlorine?
Use damp blue litmus paper, it will be bleached white if chlorine is present
How do you test for oxygen?
Relights a glowing splint
How do you test for Carbon Dioxide?
Bubble the gas through limewater, if it turns cloudy it is Carbon Dioxide
How do you test for Hydrogen?
Hydrogen makes a squeaky pop with a lit splint
What is a chemical test for water?
Add the “water” to anhydrous copper (II) sulphate. If it is water it will turn from white to blue
What is the physical test for water?
Boil the “water”, if it boils at exactly 100 degrees centigrade then it is water
What colour does Universal Indicator go for a strong acid?
Red
What colour does Universal Indicator go for a strong alkali?
Purple
What colour is Phenolphthalein in acidic conditions
Colourless
What colour is Phenolphthalein go in alkaline conditions
Bright pink
What colour is Methyl Orange in acidic conditions
Red
What colour is Methyl Orange in alkaline conditions
Yellow
