Skip to main content
Ch.16 - Aqueous Equilibria: Acids & Bases
Chapter 16, Problem 127

Classify each of the following salt solutions as neutral, acidic, or basic. See Appendix C for values of equilibrium constants. (a) Fe1NO323

Verified step by step guidance
1
Identify the ions present in the salt solution. For Fe(NO_3)_3, the ions are Fe^{3+} and NO_3^-.
Determine the nature of each ion. Fe^{3+} is a metal cation that can hydrolyze water to form acidic solutions, while NO_3^- is the conjugate base of a strong acid (HNO_3) and does not affect the pH.
Consider the hydrolysis reaction of Fe^{3+}. It can react with water to form Fe(OH)_3 and H^+, which increases the acidity of the solution.
Evaluate the overall effect of the ions on the solution's pH. Since Fe^{3+} can hydrolyze to produce H^+, the solution is expected to be acidic.
Conclude that the solution of Fe(NO_3)_3 is acidic due to the hydrolysis of Fe^{3+} ions.

Verified video answer for a similar problem:

This video solution was recommended by our tutors as helpful for the problem above.
Video duration:
4m
Was this helpful?

Key Concepts

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

Salt Hydrolysis

Salt hydrolysis refers to the reaction of a salt with water, leading to the formation of acidic or basic solutions. When a salt dissolves in water, its constituent ions can interact with water molecules, potentially altering the pH of the solution. The nature of the ions—whether they are derived from a strong acid or base—determines if the solution will be neutral, acidic, or basic.
Recommended video:

Acidic and Basic Ions

In the context of salt solutions, acidic ions (like Fe³⁺ from Fe(NO₃)₃) can donate protons to water, forming hydronium ions (H₃O⁺) and lowering the pH, while basic ions (like NO₃⁻) do not affect the pH significantly. Understanding the properties of these ions is crucial for predicting the behavior of the salt in solution and determining whether the resulting solution is acidic, basic, or neutral.
Recommended video:
Guided course
01:53
Anion Acidity and Basicity

Equilibrium Constants

Equilibrium constants (K) are numerical values that describe the ratio of products to reactants at equilibrium for a given reaction. In the context of acid-base chemistry, the equilibrium constants for dissociation reactions help predict the extent to which a salt will hydrolyze in water. By consulting equilibrium constants, one can assess the strength of the acids or bases formed from the salt's ions, aiding in the classification of the solution's pH.
Recommended video:
Guided course
01:14
Equilibrium Constant K