Tests for Substances Flashcards
How do you test for lithium?
when heated it burns with a crimson-red flame
How do you test for sodium?
when heated it burns with a yellow-orange flame
How do you test for potassium?
when heated it burns with a lilac flame
How do you test for calcium?
when heated it burns with a brick-red flame
How do you test for NH4+ (ammonium ions)?
By using sodium hydroxide and identifying the ammonia evolved.
- ammonium ions + hydroxide ions > ammonia + water
- to check whether ammonia has been produced, there will be a pungent smell, but ammonia gas will turn damp red litmus paper blue
How do you test for copper ions?
By adding it to sodium hydroxide solution:
- a blue precipitate should be formed
How do you test for Fe2+ ions?
By adding it to sodium hydroxide solution:
- a sludgy green precipitate should be formed
How do you test for Fe3+ ions?
By adding it to sodium hydroxide solution:
- a reddish brown precipitate should be formed
How do you test for chloride ions?
By using dilute nitric acid and siver nitrate solution:
- a white precipitate of silver chloride should be formed
How do you test for bromide ions?
By using dilute nitric acid and siver nitrate solution:
- a cream precipitate of silver bromide should be formed
How do you test for iodide ions?
By using dilute nitric acid and siver nitrate solution:
- a yellow precipitate of silver iodide should be formed
How do you test for SO42- (sulphate ions)?
By using hydrochloric acid and barium chloride solution:
- a white precipitate should form
How do you test for CO32- (carbonates)?
By using dilute hydrochloric acid and identifying the carbon dioxide formed:
- to test for carbon dioxide, lime water should turn cloudy
How do you test for hydrogen gas?
Burns with a squeaky pop.
How do you test for oxygen gas?
It should relight a glowing splint.
How do you test for carbon dioxide gas?
When bubbled through lime water, the lime water should go cloudy.
How do you test for ammonia gas?
It will turn damp red litmus paper blue.
(also a very strong smell)
How do you test for chlorine gas?
It will bleach damp litmus paper.
Why, when testing for the presence of ions in a substance, would an acid be added before a metal solution?
To get rid of any traces of carbonate/sulphate ions which might confuse the precipitate result.
What would be a chemical test for checking whether something contained water?
Anhydrous (white) copper sulphate should turn blue.
What is the chemical formula of nitric acid?
HNO3
What two observations can be made when magnesium burns in air?
- White flame is produced.
- White solid is produced (magnesium oxide).
