For each salt, predict whether an aqueous solution will have...

For each salt, predict whether an aqueous solution will have a pH less than, equal to, or greater than $7 .$ Explain
your answer.
(a) $\mathrm{AlCl}_{3}$
(b) $\mathrm{Na}_{2} \mathrm{~S}$
(c) $\mathrm{NaNO}_{3}$

Key Concepts

Salt Hydrolysis

Salt hydrolysis refers to the reaction of the ions from a dissolved salt with water, which produces either hydronium (H3O+) or hydroxide (OH-) ions. This process determines whether the solution becomes acidic or basic depending on the relative strengths of the conjugate acids and bases of the original salt's parent acid and base.

Conjugate Acid-Base Pairs

In aqueous solutions, the ions that constitute a salt are the conjugate base of an acid and the conjugate acid of a base. The acid or base nature of the conjugate ion depends on the strength of its parent compound. A weak acid’s conjugate base will tend to be basic, while a weak base’s conjugate acid will tend to be acidic.

Cation Hydrolysis

Cation hydrolysis occurs when cations, particularly those with high charge density such as small or highly charged metal ions, interact with water molecules. These cations can polarize water, leading to the release of protons (H+) which acidifies the solution.

Anion Hydrolysis

Anion hydrolysis occurs when anions, especially those that are the conjugate bases of weak acids, interact with water to produce hydroxide ions. This increases the basicity of the solution since the produced OH- ions raise the pH.

Spectator Ions

Spectator ions, such as those derived from strong acids and bases (for example, Na+ or NO3-), do not undergo significant hydrolysis when dissolved in water. They remain inert in the context of acid-base reactions and therefore do not affect the pH of the solution.

Transcript

Please give Ace some feedback