Qualitative Analysis Flashcards
3 types of identification
- Evolution of gas
- Formation of precipitate
- Visible colour change
What metals have coloured compounds?
Transition metals
What groups’ metals form white salts and colourless solutions
Group I, II, II metals
Colour of hydrated copper sulfate
Colour of anhydrous copper sulfate
Blue, White
Colours of compounds
1. Colourless
2. White
3. Black
4. Grey
5. Dark green
6. Light green
7. Blue/bluish green
8. Yellow/brown
9. Pale pink
10. Purple
Colourless: Group I, II , III metals
White: Salts of Group I, II, III, Amphoteric metals, Ammonium salts
Black: CuO, CuS, CoO, FeO, FeS, PbS, MnO2, I2 crystals
Grey: Metals in power form
Dark green: Chromium salts
Light green: Iron II salts
Blue/Bluish green: hydrated Cu2+ salts
Yellow/Brown: Fe3+, PbI2, AgI solutions
Pale pink: Manganese salts
Purple: KMnO4
What solutions are used to test for cations
Aqueous sodium hydroxide
Aqueous ammonia
What is produced when an amphoteric metal reacts with an acid or a base
Complex soluble salt to give colourless solutions
Test for cations and results
Check notes
Test for anions and results
Check notes
Test for gases and results
(carbon dioxide, sulfur dioxide, oxygen, hydrogen, chlorine, ammonia)
Check notes
If a gas is evolved after the the addition of HNO3, what is the compound
Either a reactive metal or a carbonate
How does litmus paper work
Litmus paper is moist to dissolve the gas and allow it to dissociate to form H+/ OH- ions
Definition of thermal decomposition
Chemical reaction in which a single compound breaks down into 2 or more simpler compounds/elements upon heating
Decomposition of carbonates give ___
_____ oxide + CO2
Decomposition of nitrate give _____
_____ oxide + nitrogen dioxide + oxygen
Decomposition of sulfites give _____
_____ oxide + sulfur dioxide gas
Sulfides Sulfites Sulfates
Nitrides Nitrites Nitrates
S2-, SO3 2-, SO4 2-
N3-, NO2 - , NO3 -
Hydrated salts definition
ioninc compounds that contain water within their crystal structure known as water of crytallisation
→ upon heating, water of crystlisation will be expelled as water vapour → leaving anhydrous salt behin
Thermal stability & Reactivity
The more reactive the metal, the more thermally stable the metal compound
Heat on oxide
All stable except
Gold and silver decompose to metal + oxygen
Heat on hydroxide
Sodium and Potassium stable
Rest decompose to metal oxide + water
(For gold and silver, further decompose to metal + oxygen)
Heat on carbonate
Sodium and Potassium stable
Rest decompose to metal oxide + CO2
(For gold and silver, further decompose to metal + oxygen)
Heating of carbonates (initial and final colour + gas evolved)
Check notes
Solubility table
Check Y3 Notes
