Question

what happens when aluminium nitrate reacts with water?

Answer 1

Task:

what happens when aluminium nitrate reacts with water?

Answer:

In water $\mathrm{Al(NO_3)_3}$ dissociates into ions:

$$\mathrm{Al(NO_3)_3} + \mathrm{H_2O} = \mathrm{Al^{3+}} + 3\mathrm{NO_3^-} + \mathrm{H^+} + \mathrm{OH^-}$$

But $\mathrm{Al^{3+}}$ with $\mathrm{OH^-}$ ions tends to form a precipitate $\mathrm{Al(OH)_3}$. But we have strong acid in this solution and this doesn't allow to form aluminium hydroxide, because $\mathrm{HNO_3}$ reacts with $\mathrm{Al(OH)_3}$ to form aluminium nitrate.

That's why we have in the solution

$$\mathrm{Al(NO_3)_3} + \mathrm{H_2O} \leftrightarrow \mathrm{Al(OH)^{2+}} + \mathrm{H^+} + \mathrm{NO_3^-}$$