Textbook Question
Calculate the pH and the percent dissociation of the hydratedcation in the following solutions. See Appendix C forthe value of the equilibrium constant.(a) 0.010 M Cr1NO323
Ch.16 - Aqueous Equilibria: Acids & Bases
Chapter 16, Problem 137
Arrange the following substances in order of increasing H3O+ concentration for a 0.10 M solution of each. (a) Zn(NO3)2 (b) Na2O (c) NaOCl (d) NaClO4 (e) HClO4
Verified step by step guidance1
Identify the nature of each substance: Determine if each substance is an acid, base, or neutral salt. This will help predict how they affect the H3O+ concentration in solution.
Consider the dissociation of each substance in water: Write the chemical equation for the dissociation of each compound in water to understand the ions produced.
Evaluate the effect on H3O+ concentration: For acids, consider how they increase H3O+ concentration. For bases, consider how they decrease H3O+ concentration by producing OH- ions. Neutral salts typically do not affect H3O+ concentration significantly.
Rank the substances: Based on the dissociation and the nature of each substance, arrange them in order of increasing H3O+ concentration.
Check for strong acids or bases: Identify if any of the substances are strong acids or bases, as they will have a more significant impact on the H3O+ concentration compared to weak acids or bases.
Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Acid-Base Theory
Acid-base theory explains how substances can donate or accept protons (H+ ions). Strong acids, like HClO4, completely dissociate in water, increasing H3O+ concentration significantly. In contrast, weak acids or neutral salts do not contribute to H3O+ concentration as effectively, making this theory essential for understanding the behavior of the given substances.
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Dissociation of Ionic Compounds
Ionic compounds dissociate into their constituent ions when dissolved in water. For example, Zn(NO3)2 dissociates into Zn²+ and NO3- ions, while Na2O reacts with water to form Na+ and OH- ions. The extent of dissociation and the nature of the ions produced influence the resulting H3O+ concentration in the solution.
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pH and H3O+ Concentration
The pH scale measures the acidity or basicity of a solution, with lower pH values indicating higher H3O+ concentrations. The relationship between pH and H3O+ is logarithmic, meaning that a small change in pH corresponds to a significant change in H3O+ concentration. Understanding this relationship is crucial for arranging the substances based on their H3O+ levels.
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