Group 2 Flashcards
Why do the elements have more vigorous reactions down group 2?
Down the group, less energy is required to ionise the atoms.
How do group 2 elements react with oxygen?
2Mg + O2 -> 2MgO
Group 2 elements burn vigorously when heated in air to form white oxides
How do group 2 elements react with water?
Group 2 elements react with water forming a metal hydroxide and hydrogen.
The general equation, using M for metal is :
M + 2H2O -> M(OH)2 + H2
How does calcium react with water?
Calcium reacts to form a white precipitate of calcium hydroxide.
How do group 2 elements react with acids?
Group 2 elements react with acids to form a salt + hydrogen.
Mg + 2HCl -> MgCl2 + H2
Give an observation that would be made during the reaction of calcium with hydrochloric acid to form calcium chloride.
State how the observation would be different if magnesium was used.
Effervescence would be observed.
If magnesium was used, the effervescence would be less vigorous.
Describe the reaction of CaO with water.
The white oxide expands as water is added, producing a lot of steam.
Describe the solubility of group 2 hydroxides down group 2.
Going down group 2, the hydroxides become more soluble.
More OH- ions are released into the solution, which becomes more alkaline.
What is calcium carbonate used for in industry?
- Neutralising acidic soils
- Treating acid indigestion
Describe how calcium hydroxide acts as a base when used to neutralise soil.
If soils are too acidic, crops will not grow well.
Farmers can add controlled amounts of the base calcium hydroxide, which neutralises the acid in the soil, to increase soil pH to the desired value.
Describe how calcium carbonate/magnesium hydroxide helps to treat acid indigestion.
If stomach acid gets into the oesophagus, it causes inflammation of the tissues there, causing pain called acid indigestion.
If the bases calcium carbonate/magnesium hydroxide are taken they will neutralise this acid, removing the pain.
