Domanda del libro di testo
The pH of a solution of NH3 and NH4Br is 8.90. What is the molarity of NH4Br if the molarity of NH3 is 0.016 M?
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Ch.17 - Applications of Aqueous Equilibria
McMurry8th EditionChemistryISBN: 9781292336145
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TOC.tableOfContents
- Ch.1 - Chemical Tools: Experimentation & Measurement170
- Ch.2 - Atoms, Molecules & Ions160
- Ch.3 - Mass Relationships in Chemical Reactions169
- Ch.4 - Reactions in Aqueous Solution199
- Ch.5 - Periodicity & Electronic Structure of Atoms102
- Ch.6 - Ionic Compounds: Periodic Trends and Bonding Theory92
- Ch.7 - Covalent Bonding and Electron-Dot Structures61
- Ch.8 - Covalent Compounds: Bonding Theories and Molecular Structure59
- Ch.9 - Thermochemistry: Chemical Energy122
- Ch.10 - Gases: Their Properties & Behavior155
- Ch.11 - Liquids & Phase Changes54
- Ch.12 - Solids and Solid-State Materials73
- Ch.13 - Solutions & Their Properties120
- Ch.14 - Chemical Kinetics98
- Ch.15 - Chemical Equilibrium125
- Ch.16 - Aqueous Equilibria: Acids & Bases110
- Ch.17 - Applications of Aqueous Equilibria147
- Ch.18 - Thermodynamics: Entropy, Free Energy & Equilibrium86
- Ch.19 - Electrochemistry154
- Ch.20 - Nuclear Chemistry96
- Ch.21 - Transition Elements and Coordination Chemistry156
- Ch.22 - The Main Group Elements187
- Ch.23 - Organic and Biological Chemistry51
Capitolo 17, Problema 57
Calculate the pH of a solution that is 0.25 M in HF and 0.10 M in NaF.
Guida verificata passo dopo passo1
Identify that the solution is a buffer solution, consisting of a weak acid (HF) and its conjugate base (F^- from NaF).
Use the Henderson-Hasselbalch equation for buffer solutions: \( \text{pH} = \text{pK}_a + \log \left( \frac{[\text{A}^-]}{[\text{HA}]} \right) \), where \([\text{A}^-]\) is the concentration of the conjugate base and \([\text{HA}]\) is the concentration of the weak acid.
Look up or calculate the \(\text{pK}_a\) of HF. The \(\text{K}_a\) of HF is typically around \(6.8 \times 10^{-4}\), so \(\text{pK}_a = -\log(\text{K}_a)\).
Substitute the given concentrations into the Henderson-Hasselbalch equation: \( [\text{A}^-] = 0.10 \text{ M} \) and \( [\text{HA}] = 0.25 \text{ M} \).
Calculate the pH using the equation: \( \text{pH} = \text{pK}_a + \log \left( \frac{0.10}{0.25} \right) \).
Concetti chiave
Ecco i concetti essenziali che devi comprendere per rispondere correttamente alla domanda.
Weak Acid and Conjugate Base
HF (hydrofluoric acid) is a weak acid that partially dissociates in solution, while NaF (sodium fluoride) provides the conjugate base F-. The presence of both a weak acid and its conjugate base in solution creates a buffer system, which helps maintain a relatively stable pH when small amounts of acid or base are added.
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Percorso guidato
01:46
Conjugate Acid-Base Relationships
Henderson-Hasselbalch Equation
The Henderson-Hasselbalch equation is a mathematical formula used to calculate the pH of a buffer solution. It is expressed as pH = pKa + log([A-]/[HA]), where pKa is the negative logarithm of the acid dissociation constant (Ka) of the weak acid, [A-] is the concentration of the conjugate base, and [HA] is the concentration of the weak acid.
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Percorso guidato
02:40Henderson-Hasselbalch Equation
Acid Dissociation Constant (Ka)
The acid dissociation constant (Ka) quantifies the strength of a weak acid in solution. It is defined as the equilibrium constant for the dissociation of the acid into its ions. For HF, the Ka value is essential for determining the pKa, which is needed in the Henderson-Hasselbalch equation to calculate the pH of the buffer solution.
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Percorso guidato
03:50Characteristics of Ka and Kb