Why do solutions of many metal salts turn out acidic?

1. A dissolved metal ion binds a shell of water molecules closely around itself. 2. The aluminium ion, for instance, holds six water molecules in that first shell. 3. The metal ion pulls electron density away from those bound water molecules. 4. One of them then donates a proton to a free water molecule, making hydronium. 5. The hydrated metal ion is therefore behaving as a weak acid. 6. The remaining bound waters can lose protons in turn, so the process is stepwise. _Source: OpenStax Chemistry (CC BY 4.0), Ch 14 "Acid-Base Equilibria", section 14.4 Hydrolysis of Salt Solutions_