solubilty of hydroxides Flashcards
1
Q
what happens when not soluble?
A
its a white precipitate
2
Q
is magnesium hydroxide soluble in water
A
no
Mg2+ + 2OH-> Mg(OH)2 (S)
3
Q
why does a suspension of Mg(OH)2 in water appear slightly alkaline (pH9)?
A
some hydroxide ions may have been produced with a very slight dissolving
4
Q
state a use of magnesim hydroxide
state a equation
also why is it safe to use
also state what is it preferable to and why
A
used in medicine. to neutralise excess acid in the stomach also treats constipation Mg(OH)2 + 2HCl-> MgCl2 + 2H2O its so weakly alkaline so its safe. also preferable to calcium carbonate as it doesnt produce carbon dioxide
5
Q
how soluble is calcium hydroxide in water.
state a use for it.
also state an equation.
A
reasonably soluble Ca(OH)2 + CO2 -> CaCO3 + H20 uses: used to neutralise acidic soils also used as limewater to test for carbon dioxide. limewater turns cloudy as white calcium carbonate is produce.
6
Q
trend down the group?
A
become more soluble
