Inorganic 2: Group 2 Flashcards
What ions do group 2 elements form?
2+ ions
Why are group 2 elements called alkaline earth metals?
Their oxides and hydroxides are alkaline
Are found in the Earth’s crust
Describe the trend in reactivity down group 2.
Reactivity increases as you go down the group
What are CaO and Ca(OH)2 used for?
Neutralising acids in soil
Most plants have an optimum level of acidity or alkalinity
How does magnesium react with water and steam?
Reacts very slowly with cold water, but rapidly with steam
Mg(s) + H2O(g) –> MgO(s) + H2(g)
How does calcium react with water?
More vigorously than magnesium
Ca(s) + 2H2O(l) –> Ca(OH)2 + H2(g)
Describe trend in reactivity of group 2 elements with water.
Reactivity increases
M(s) + 2H2O(l) –> M(OH)2(aq) + H2(g)
Describe trend in solubility of hydroxides down group 2.
Solubility of hydroxides increases down group 2
Describe the solubility of Mg(OH)2.
Almost insoluble
What is Mg(OH)2 used for?
Milk of magnesia
Used to treat indigestion
Describe solubility of Ca(OH)2.
Sparingly soluble
Describe solubility of Ba(OH)2.
Strongly alkaline solution
Ba(OH)2(s) + H2O(l) –> Ba2+(aq) + 2OH-
Describe the trend in solubility of sulfates down group 2.
Solubility decreases
MgSO4 is soluble
BaSO4 is virtually insoluble
What is BaSO4 used for in medicine?
Barium meal
Outlines the gut in medical X-Rays
What is BaSO4 used for in chemistry?
As a test for sulfate ions
1) Acidify sample solution with HNO3 or HCl to remove carbonate ions as CO2, as carbonate ions would also form a white precipitate
2) Add BaCl2 to the sample solution
3) A white precipitate of BaSO4 will form if sulfate ions are present
