CHEM---base

(1)
MgO, Mg(OH)2, CaO, Ca(OH)2
They are all weak bases.
It's because when they are dissolved in water, only a small amount of OH- will be produced. The reason is, they are insoluble, or only slightly soluble in water.
A strong base is a base which 100% ionized in water to give OH-. A weak base usually only 5% ionized.
Some people may confused about all metal oxides are weak bases. However, it isn't correct. Sodium oxide, potassium oxide and barium oxide are all strong metal oxide bases.

(2)
MgO, Mg(OH)2, CaO, are all white coloured solid
Ca(OH)2 is a colourless solution

NaO of course is a strong base because it's soluble in water (alkali).
Group I metal oxides and metal hydroxide are usually colourless alkaline liquid.

1.係唔係weak base???

metal oxide is weak base.
There fore MgO and CaO is weak base.

Ca(OH)2 and Mg(OH)2 is weak base.
Because they are sightly soluted in the water.

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2.佢地係唔係colourless liquid


唔係
MgO and CaO are black.
Ca(OH)2 and Mg(OH)2 are white.

2007-04-24 13:10:16 補充：
hey!
Ca(OH)2 is just sightly soluted in the water
Why it is a colourless solution?