Cation Hydrolysis & Hydration of Metal Ions

Vocabulary flashcards covering key terms and explanations related to hydration and hydrolysis of metal ions, emphasizing the acidity differences between aluminum and copper sulfate solutions.

Hydration (of ions)

The process in which water molecules coordinate to a metal ion, forming a hydrated complex.

Hydrated Ion

A metal ion surrounded by a specific number of water molecules, e.g., [Cu(H₂O)₂]²⁺ for Cu²⁺ with two waters.

Hydrolysis (of hydrated ions)

The reaction in which a hydrated metal ion donates protons to water, generating hydronium (H₃O⁺) and increasing solution acidity.

Cation Hydrolysis

A type of hydrolysis where positively charged metal ions react with water, often producing acidic solutions.

Hydronium Ion (H₃O⁺)

The ion formed when a proton (H⁺) associates with a water molecule; responsible for acidity in aqueous solutions.

Aluminum Ion (Al³⁺)

A trivalent metal cation that, upon hydrolysis, releases three hydronium ions, making its solutions strongly acidic.

Copper(II) Ion (Cu²⁺)

A divalent metal cation that releases two hydronium ions upon hydrolysis, giving a less acidic solution than Al³⁺.

Aluminum Sulfate Solution

An aqueous solution of Al₂(SO₄)₃ whose hydrolysis produces three moles of H₃O⁺ per formula unit, resulting in high acidity.

Copper(II) Sulfate Solution

An aqueous solution of CuSO₄ whose hydrolysis produces two moles of H₃O⁺ per formula unit, giving moderate acidity.

Ion Charge

The electrical charge carried by an ion; determines the maximum number of water molecules in its hydration shell.

Acid Strength of Salt Solutions

The extent to which a salt’s cation hydrolyzes to release H₃O⁺; higher hydronium production means stronger acidity.

Mole (chemistry)

The SI unit representing 6.022×10²³ entities, used to count the number of ions, molecules, or atoms in reactions.

Maximum Hydration Number

The highest number of water molecules that can coordinate to a metal ion, often equal to the ion’s positive charge in simple cases.

Comparison of Al³⁺ vs. Cu²⁺ Acidity

Because Al³⁺ yields three H₃O⁺ and Cu²⁺ yields two H₃O⁺ upon hydrolysis, Al³⁺ solutions are more acidic than Cu²⁺ solutions.