🧪 | Unit 12 | Experimental techniques and chemical analysis Flashcards
A substance is held into the flame of a Bunsen burner using a wire. The flame turns red.
What is the substance?
Lithium ❤️
A substance is held into the flame of a Bunsen burner using a wire. The flame turns yellow.
What is the substance?
Sodium 💛
A substance is held into the flame of a Bunsen burner using a wire. The flame turns purple.
What is the substance?
Potassium 💜
A substance is held into the flame of a Bunsen burner using a wire. The flame turns orange-red.
What is the substance?
Calcium 🧡
A substance is held into the flame of a Bunsen burner using a wire. The flame turns blue-green.
What is the substance?
Copper (II) 💚
What is the precipitate left behind on addition of NaOH to a metal cation?
The metal hydroxide
NaOH is added to a substance. A green precipitate is formed. In excess, it dissolves into a dark green solution.
In aqueous ammonia, a grey-green precipitate is formed which is insoluble in excess.
What is the substance?
Chromium (III)
NaOH is added to a substance. A green precipitate is formed. When NaOH is added in excess, the precipitate remains insoluble.
What is the substance?
Iron (II)
NaOH is added to a substance. A light blue precipitate is formed. When NaOH is added in excess, the precipitate remains insoluble.
What is the substance?
Copper (II)
A red-brown precipitate is formed when a substance reacts with either aqueous ammonia or NaOH. When NaOH/ammonia is added in excess, the precipitate remains insoluble.
What is the substance?
Iron (III)
NaOH is added to a substance. A white precipitate is formed. When NaOH is added in excess, the precipitate dissolves to form a colourless solution.
When NH₃ is added to the substance, a white precipitate is formed. When NH₃ is added in excess, the precipitate remains insoluble.
What is the substance?
Aluminium
NaOH is added to a substance. A white precipitate is formed. When NaOH is added in excess, the precipitate dissolves to form a colourless solution.
When NH₃ is added to the substance, a white precipitate is formed. When NH₃ is added in excess, the precipitate dissolves to form a colourless solution.
What is the substance?
Zinc
NaOH is added to a substance. A white precipitate is formed. When NaOH is added in excess, the precipitate remains insoluble.
What is the substance?
Calcium
NaOH is added to a substance. When it is warmed gently, ammonia is produced.
What is the substance?
Ammonium
Tests for Aluminium
- NaOH: white precipitate formed, dissolves in excess to form a colourless solution
- NH₃: white precipitate formed, insoluble in excess
Tests for Zinc
- NaOH: white precipitate formed, dissolves in excess to form a colourless solution
- NH₃: white precipitate formed, dissolves in excess to form a colourless solution
Tests for Calcium
- NaOH: white precipitate formed, insoluble in excess
- NH₃: no visible change, or a faintly visible white precipitate
- Flame test: orange-red flame
Tests for Chromium (III)
- NaOH: green precipitate formed, dissolves in excess to form a green solution
- NH₃: grey-green precipitate, insoluble in excess
Tests for Copper (II)
- NaOH: light blue precipitate formed, insoluble in excess
- NH₃: light blue precipitate formed, dissolves in excess to form a dark blue solution
- Flame test: blue-green flame
Test for Ammonium
- NaOH: Ammonia given off when warmed gently
Tests for Iron (II)
- NaOH: green precipitate formed, insoluble in excess
- NH₃: green precipitate formed, insoluble in excess
Tests for Iron (III)
- NaOH: red-brown precipitate formed, insoluble in excess
- NH₃: red-brown precipitate formed, insoluble in excess
Test for CO₂
Bubbling through limewater
Positive obv: limewater turns milky
Test for O₂
Glowing splint test
Positive obv: splint relights
Test for H₂
Lighted splint test
Positive obv: a “squeaky pop” sound
Test for Ammonia
Warm aqueous ammonium in a test tube and place a damp red litmus paper above the solution.
Positive obv: red litmus paper turns blue
Test for SO₂
Add to acidified potassium (vii) manganate
Positive obv: purple to colourless
Solubility of Ethanoates
All are soluble
Solubility of Nitrates
All are soluble
All salts of sodium, potassium and ammonium
All are soluble
Solubility of Chlorides
All are soluble except
- silver chloride
- lead (II) chloride
Solubility of Sulfates
All are soluble except
- barium sulfate
- lead (II) sulfate
- calcium sulfate
Solubility of Carbonates
All are insoluble except
- sodium carbonate
- potassium carbonate
- ammonium carbonate
Solubility of Hydroxides
All are insoluble except
- sodium hydroxide
- potassium hydroxide
- calcium hydroxide (slightly)
Difference between a strong acid and a weak acid?
Strong acids ionize completely
Weak acids ionize partially
Difference between a strong base and a weak base?
Strong bases are soluble
Weak bases are not very soluble
Test for carbonate
Adding dilute acid will produce CO₂
Test for nitrate
Add aqueous NaOH and aluminium foil, and warm gently. Ammonia will be produced.
Characteristics of ammonia
Pungent smell, turns damp red litmus paper blue
Test for sulfite
Add a dilute acid and warm gently.
The gas produced will decolourise acidified aqueous potassium (VII) manganate solution
