[mjaree]

Hi,

The question is:

When solutions of carbonic acid and magnesium hydroxide react, which of the following are NOT present in the net ionic equation?

I hydrogen ion II Carbonate ion III Magnesium Ion IV Hydroxide Ion

The answer is Hydrogen Ion and Hydroxide Ion.
But why is it not?

H2CO3(weak acid doesn't dissociate) + Mg(OH)2(Solid) -> MgCO3(Solid)+H20

Thanks

[onn]

Weak acid does dissociate, and that is how your ionic equation is supposed to show. What it doesn't do is to dissociate completely, so percentage yield won't be 100% as you would expect from any reactions, really