Group 2 compounds: solubility in water

• Hydroxide solubility increases as you go down the group. Mg forms a white precipitate, Ca forms a cloudy solution:

  M2+(aq) + 2OH- -> M(OH)2(s)

  and the rest are fully soluble.

  Thermal stability increases as group descends
• The sulphates become less soluble as the group descends- Mg forms a solution, Ca forms a cloudy solution, Sr and Ba form a white precipitate.

  M2+(aq) + SO42-(aq) -> MSO4(s)

  (M= Ca, Sr, Ba)
• All group 2 carbonates are insoluble and form white precipitates.

  M2+(aq) + CO32-(aq) -> MCO3(s)

  Thermal stability increases as group descends.