Test tube reactions Flashcards
1
Q
What happens when a hexaaqua ion dissolves in an alkaline solution?
A
- precipitate formed
- water released
- M2+
- [M(H2O)6]2+ + 2OH- ⇌ [M(H2O)4(OH)2] (s) + 2H2O
- ammonia acts in the same way by removing protons
2
Q
When do carbonates of TM ions exist?
A
- in the +2 state
- those of ions in +3 state do not
3
Q
WHy do transition metal carbonates not always forms?
A
- M3+ are suffieciently acidic to react with carbonate ions to release carbon dioxide and a precipitate of the metal hydroxide
4
Q
What is the ovarall reaction between the carbonate and iron (III) hexaaqua ion?
A
- 2[Fe(H2O)6]3+ (aq) + 3CO32- (aq) → 2Fe(H2O)3(OH)3 + 3CO2 (G) + 3H2O (l)
5
Q
How do carbonate ions act as a base?
A
- combine with H3O+ ion 2 stages
- first make hydrogencarbonate ions
- CO32- (aq) + H3O+ ⇌ HCO3- (aq) + H2O
- then to give carbon dioxide and water
- HCO3-(aq) + H3O+ ⇌ CO2(g) + H2O (l)
6
Q
What happens with M2+ ions react with carbonates
A
- [M(H2O)6]2+ (aq) + CO32- → MCO3 (s) + 6H2O
7
Q
What does amphoteric mean?
A
- showing both acidic and basic properties
8
Q
How does hydorxides of alimuinium show amphoteric properties?
A
- reacts with acids :
- Al(H2O)3(OH)3 + HCl → [Al(H2O)6]3+ + 3Cl-
- reacts with bases
- Al(H2O)3(OH)3 + OH- → [Al(OH)4]- +3H2O
- reacts with sodium hydroxide to give a coloureless solution of sodium tertrahydroaluminate
