effect of water on ph of acid

By the fact that:

pH = - log [H+]

where [H+] is the concentration of hydrogen ion.

For acid, no matter strong or weak, will have its [H+] decreased when water is added to it and hence its pH value will rise.

For alkali, no matter strong or weak, will have its concentration of hydroxide ion, [OH-] decreases.

Then by the fact that [H+] x [OH-] is a constant, we can deduce that [H+] increases and therefore its pH value will drop.

Oh! I think like this.

After we add water to acidic solution, the ph value will increase, the mole will decrease.

Oppositely, if we add water to basic solution, the ph value will decrease, and the mole will increase.

2010-02-20 15:05:04 補充：
That means it will effect its ph value and the value of mole.