3.2.2 - Group 2 metals Flashcards
Test for sulfates
-Add HCl (needed to react with carbonate impurities which would form a white Barium carbonate precipitate, giving false result)
-Add BaCl2
Postive result for test for sulfates
White ppt (BaSO4)
Why does melting point decrease down the metal groups? (3)
- Atomic radius increases
- Charge density decreases
- Weaker force of attraction between delocalised electron cloud and positive metal ions
Group 2 - solubility of sulphates trend
Decreases down the group
Group 2 - solubility of hydroxides trend + reason
Increases down the group, atoms get larger, electron further from nucleus, easier to remove, hence more reactive
Why is barium sulphate used in hospitals?
- Shows up on x-rays
- Is insoluble
Extraction of titanium (3 step)
- TiO2 converted to TiCl4 by heating with carbon and chlorine gas - TiO2 + 2 Cl2 + 2C —> TiCl4 + 2 CO
- Passed through fractional distillation to increase purity
- Reduced via magnesium at 1000 degrees
TiCl4 + 2Mg -> Ti + 2MgCl2
How do you remove sulfur dioxide from flue gases?
Dissolve calcium carbonate/oxide in water, and spray sulphur dioxide on it (wet scrubbing)
Mg + steam
Mg (s) + H2O (g) - MgO (s) + H2 (g)
MgO + warm water
Mg + 2 H2O - Mg(OH)2 + H2
Magnesium hydroxide use
- Antacid
- Works to neutralise stomach acid, does not produce CO2
Why is Titanium expensive?
- Na/Mg cost
- Batch process (slower/more labour intensive),
- High temperatures required
Why is calcium in sulfate reaction slow? (3)
- Calcium sulfate is insoluble
- Calcium sulfate coats the surface of the calcium
- Coating prevents further reaction by the acid
Test for group 2 ions (3)
- Dip nichrome wire in conc HCL
- Dip into sample
- Place loop into blue Bunsen flame
Result for calcium in group 2 ion test
Dark red
