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Ch.17 - Applications of Aqueous Equilibria
Chapter 17, Problem 48c

Is the pH greater than, equal to, or less than 7 after the neutralization of each of the following pairs of acids and bases? (c) KOH and HI

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1
Identify the nature of the acid and base involved in the reaction. KOH is a strong base, and HI is a strong acid.
Write the balanced chemical equation for the neutralization reaction: \[ \text{KOH} + \text{HI} \rightarrow \text{KI} + \text{H}_2\text{O} \]
Recognize that the neutralization of a strong acid with a strong base typically results in a neutral solution, meaning the pH should be close to 7.
Consider the products of the reaction: KI is a salt formed from a strong acid and a strong base, which does not hydrolyze in water to affect the pH.
Conclude that the pH of the solution after neutralization is expected to be equal to 7, as neither the salt nor the water formed will alter the pH.

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Key Concepts

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

Neutralization Reaction

A neutralization reaction occurs when an acid reacts with a base to produce water and a salt. In this process, the acidic properties of the acid and the basic properties of the base cancel each other out, typically resulting in a solution that is closer to neutral, with a pH around 7. The specific pH after neutralization depends on the strength of the acid and base involved.
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Strong Acids and Bases

Strong acids, like hydroiodic acid (HI), completely dissociate in water, releasing all their hydrogen ions (H+). Similarly, strong bases, such as potassium hydroxide (KOH), fully dissociate to release hydroxide ions (OH-). The complete dissociation of both a strong acid and a strong base in a neutralization reaction typically results in a neutral pH of 7, assuming equal molar concentrations.
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pH Scale

The pH scale measures the acidity or basicity of a solution, ranging from 0 to 14. A pH of 7 is considered neutral, values below 7 indicate acidic solutions, and values above 7 indicate basic solutions. Understanding the pH scale is crucial for predicting the outcome of acid-base reactions, particularly in determining whether the resulting solution will be acidic, neutral, or basic after neutralization.
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