Group 2 - chemical properties Flashcards
What is the trend in reactivity with water down the group?
the metals get more reactive down the group
What type of reaction is the reaction with water?
a redox reaction
What are the steps for the reaction with water?
M = any group 2 element
M<span>+0</span> (s) + 2H2O+1 (l) → M(OH)2+2 (aq) + H2+0 (g)
What are the uses of magnesium hydroxide?
it is milk of magnesia and is used in indigestion remidies to neutralise excess stomach acid which causes heartburn, indigestion and wind
What are the uses of slaked lime?
used to treat excess acidity in soil
Why can titanium not be extracted by the usual metal extraction techniques?
metal is usually extracted by this process:
metal oxide + carbon → metal + carbon dioxide
however titanium reaction with carbon to form titanium carbide, this is brittle
How is titanium extracted?
titanium oxide is reactied with chlorine and carbon (coke) to for titanium chloride (TiCl4) and carbon monoxide
titanium is then reduced by reaction with magnesium
TiCL4 (l) + 2Mg (s) → 2MgCl2 (s) + Ti (s)
What is the trend in solubilities of hydroxides?
going down the group they become more soluble
all are white solids
What do the different hydroxides form in water?
Mg(OH)2 - almost insoluble - sold as a suspension in water
Ca(OH)2 - sparingly soluble and a solution is used as lime water
Sr(OH)2 is more soluble
Ba(OH)2 dissolves to produce a strongly alkaline solution:
Ba(OH)2 (s) + aq → Ba2+ (aq) + 2OH-
How does the solubility of sulfates change?
the opposite
they become less soluble going down the group
What is the use of barium sulfate?
virtualy insoluble
taken by mouth as a barium meal to outline the gut in medical X-rays
it is very good at absorbing X-rays
despite barium compounds being highly toxic, it is safe because it is so insoluble
How is a test for sulfate ions in solution carried out?
the solution is acidified with nitric or hydrogchloric acid
then barium chloride solution is added to the solution under test and if sulfate is present a white precipitate is formed
Ba2+ (aq) + SO42- (aq) → BaSO4 (s)
Why is acid added in the test for sulfate ions?
the addition of acid removes carbonate ions as carbon dioxide
barium carbonate is also a white insoluble solid, which would be indistinguishable from barium sulfate
What colour is barium sulfate?
white
use in tests
