Is AlCl3 acidic or basic?
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- Posts: 23858
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Re: Is AlCl3 acidic or basic?
The Cl- anion is neutral, but the Al3+ is not. From the reaction AlCl3 + 3H2O <=> Al(OH)3 + 3HCl, HCl is a strong acid, so it will dissociate in water to form H+ and Cl-. As a result of this reaction, the solution will be acidic, with a pH < 7.
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Re: Is AlCl3 acidic or basic?
Chem_Mod wrote:The Cl- anion is neutral, but the Al3+ is not. From the reaction AlCl3 + 3H2O <=> Al(OH)3 + 3HCl, HCl is a strong acid, so it will dissociate in water to form H+ and Cl-. As a result of this reaction, the solution will be acidic, with a pH < 7.
so does this mean AlCl3 is a weak base since its conjugate acid is strong?
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Re: Is AlCl3 acidic or basic?
Emily_Stenzler_2H wrote:Chem_Mod wrote:The Cl- anion is neutral, but the Al3+ is not. From the reaction AlCl3 + 3H2O <=> Al(OH)3 + 3HCl, HCl is a strong acid, so it will dissociate in water to form H+ and Cl-. As a result of this reaction, the solution will be acidic, with a pH < 7.
so does this mean AlCl3 is a weak base since its conjugate acid is strong?
No, it means AlCl3 is a weak acid, because the only part of the molecule that is contributing to the pH of the solution is the Al+3 ion. The conjugate base of a strong acid has very little impact on the pH of the solution (with the case of Cl- and its conjugate acid, HCl). AlOH3, the conjugate base for Al3+, is a weak base and so Al3+ will be a weak acid.
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