2 - Solubility and uses of group 2 Flashcards
What is the form of group 2 hydroxides and sulfates when solid?
White solids
What is the trend in solubility of the hydroxides of the elements Mg-Ba?
Increases down the group
Mg(OH)2 is sparingly soluble. What does this mean?
Its solubility is low
What is Mg(OH)2 used for in medicine?
Used in indigestion tablets to neutralise excess acid in the stomach
What is Ca(OH)2 used for in agriculture?
Used to neutralise acidic soils
In both cases of Mg(OH)2 and Ca(OH)2, the reaction is..
H+ (aq) + OH- (aq) → H2O (l)
What is the trend in solubility of the sulfates of the elements Mg-Ba?
Decreases down the group
What group 2 sulfate is insoluble?
BaSO4
What is BaSO4 used for in medicine?
- Patients are given a suspension of Barium sulfate
- Barium sulfate is opaque to X rays
- This coats tissues so that they show up on x-rays, showing the structure of organs
What is acidified BaCl2 used for?
To test for sulfate ions
How do we know that sulfate ions are present when BaCl2 is added?
A white precipitate of BaSO4 will form
Why does the BaCl2 need to acidified with HCl first?
To get rid of any sulfites or carbonates
- These also produce a white precipitate so could give a false positive result
What can magnesium be used for?
Used in the extraction of Titanium from its ore
What are the 3 steps in extracting titanium?
1) TiO2 is converted to TiCl4 (liquid) at 900°C
2) The TiCl4 is purified by fractional distillation in an agron atmosphere
3) The Ti is extracted by Mg in an argon atmosphere at 500°C
Why is titanium expensive?
- Mg is expensive
- High temperatures are required
