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Ch.16 - Acid-Base Equilibria
Chapter 16, Problem 90b

Which member of each pair produces the more acidic aqueous solution: (b) CuCl or Cu1NO322

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Identify the cation and anion in each compound: CuCl contains Cu^+ and Cl^-, while Cu(NO_3)_2 contains Cu^2+ and NO_3^-.
Consider the hydrolysis of the cations: Cu^+ is less likely to hydrolyze compared to Cu^2+, which can hydrolyze to form H^+ ions, increasing acidity.
Evaluate the anions: Cl^- is a weak conjugate base of a strong acid (HCl) and does not affect acidity, while NO_3^- is also a weak conjugate base of a strong acid (HNO_3) and does not affect acidity.
Compare the hydrolysis of the cations: Since Cu^2+ can hydrolyze to produce H^+ ions, Cu(NO_3)_2 is expected to produce a more acidic solution than CuCl.
Conclude that Cu(NO_3)_2 produces a more acidic aqueous solution than CuCl due to the hydrolysis of Cu^2+.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Acidity and pH

Acidity refers to the concentration of hydrogen ions (H+) in a solution, which determines its pH level. A lower pH indicates a more acidic solution. Understanding how different substances dissociate in water to release H+ ions is crucial for comparing their acidity.
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Metal Cation Behavior

Metal cations can influence the acidity of a solution based on their charge and size. Cations like Cu²⁺ can hydrolyze in water, forming acidic solutions by releasing H+ ions. The extent of this hydrolysis is key to determining which compound is more acidic.
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Complex Ion Formation

Complex ions form when metal cations coordinate with ligands, affecting their properties, including acidity. For example, Cu(NO3)2 may form complex ions that can alter the pH of the solution compared to simpler salts like CuCl. Understanding these interactions is essential for predicting acidity.
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