Textbook Question
What is the pH at the equivalence point for the titration of 0.10 M solutions of the following acids and bases, and which of the indicators in Figure 17.5 would be suitable for each titration? (a) HNO2 and NaOH
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Ch.17 - Applications of Aqueous Equilibria
McMurry8th EditionChemistryISBN: 9781292336145
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Table of contents
- Ch.1 - Chemical Tools: Experimentation & Measurement143
- Ch.2 - Atoms, Molecules & Ions134
- Ch.3 - Mass Relationships in Chemical Reactions149
- Ch.4 - Reactions in Aqueous Solution157
- Ch.5 - Periodicity & Electronic Structure of Atoms92
- Ch.6 - Ionic Compounds: Periodic Trends and Bonding Theory73
- Ch.7 - Covalent Bonding and Electron-Dot Structures47
- Ch.8 - Covalent Compounds: Bonding Theories and Molecular Structure51
- Ch.9 - Thermochemistry: Chemical Energy104
- Ch.10 - Gases: Their Properties & Behavior138
- Ch.11 - Liquids & Phase Changes43
- Ch.12 - Solids and Solid-State Materials56
- Ch.13 - Solutions & Their Properties98
- Ch.14 - Chemical Kinetics79
- Ch.15 - Chemical Equilibrium107
- Ch.16 - Aqueous Equilibria: Acids & Bases94
- Ch.17 - Applications of Aqueous Equilibria125
- Ch.18 - Thermodynamics: Entropy, Free Energy & Equilibrium66
- Ch.19 - Electrochemistry130
- Ch.20 - Nuclear Chemistry73
- Ch.21 - Transition Elements and Coordination Chemistry122
- Ch.22 - The Main Group Elements155
- Ch.23 - Organic and Biological Chemistry43
Chapter 17, Problem 87
On the same graph, sketch pH titration curves for the titra-tion of (1) a strong acid with a strong base and (2) a weak acid with a strong base. How do the two curves differ with respect to the following? (a) The initial pH
Verified step by step guidance1
insert step 1> Identify the acids and bases involved in each titration. For the strong acid-strong base titration, consider an example like HCl (strong acid) and NaOH (strong base). For the weak acid-strong base titration, consider an example like CH3COOH (acetic acid, weak acid) and NaOH (strong base).
insert step 2> Understand the initial pH of each solution before any base is added. For the strong acid, the initial pH is low because strong acids dissociate completely in water, resulting in a high concentration of H+ ions. For the weak acid, the initial pH is higher than that of the strong acid because weak acids only partially dissociate in water.
insert step 3> Sketch the pH titration curve for the strong acid with a strong base. Start with a low pH, and as the base is added, the pH will increase rapidly near the equivalence point, which is typically around pH 7 for strong acid-strong base titrations.
insert step 4> Sketch the pH titration curve for the weak acid with a strong base. Start with a higher initial pH compared to the strong acid. The curve will have a more gradual slope and the equivalence point will be above pH 7 due to the formation of a weak conjugate base.
insert step 5> Compare the initial pH of both titration curves. The strong acid-strong base titration starts at a lower pH compared to the weak acid-strong base titration, reflecting the complete dissociation of the strong acid versus the partial dissociation of the weak acid.
Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Strong Acid vs. Weak Acid
A strong acid completely dissociates in solution, resulting in a high concentration of hydrogen ions (H+) and a low initial pH. In contrast, a weak acid only partially dissociates, leading to a higher initial pH due to the lower concentration of H+ ions. This fundamental difference affects the shape of the titration curve.
Recommended video:
Guided course
01:15
Calculating Percent Ionization of Weak Acids
Titration Curves
Titration curves graph the pH of a solution as a function of the volume of titrant added. For a strong acid-strong base titration, the curve shows a sharp increase in pH at the equivalence point, while a weak acid-strong base titration displays a more gradual slope and a buffer region before the equivalence point, reflecting the weak acid's resistance to pH changes.
Recommended video:
Guided course
02:16Acid-Base Titration Curves
Equivalence Point
The equivalence point in a titration is reached when the amount of titrant added is stoichiometrically equivalent to the amount of substance in the solution. For strong acid-strong base titrations, this point typically occurs at pH 7, while for weak acid-strong base titrations, it occurs at a pH greater than 7 due to the formation of a weak conjugate base.
Recommended video:
Guided course
01:07At the Equivalence Point
Related Practice
Textbook Question
The equivalence point was reached in titrations of three unknown acids at pH 9.16 (acid A), 8.88 (acid B), and 8.19 (acid C). (a) Which is the strongest acid?(b) Which is the weakest acid?
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Textbook Question
Make a rough plot of pH versus milliliters of acid added for the titration of 50.0 mL of 1.0 M NaOH with 1.0 M HCl. Indicate the pH at the following points, and tell how many milliliters of acid are required to reach the equivalence point. (a) At the start of the titration(b) At the equivalence point (c) After the addition of a large excess of acid
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Textbook Question
Consider the titration of 40.0 mL of 0.250 M HF with 0.200 M NaOH. How many milliliters of base are required to reach the equivalence point? Calculate the pH at each of the following points. (d) After the addition of 80.0 mL of base
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