Domanda del libro di testo
Identify each substance as an acid or a base and write a chemical equation showing how it is an acid or a base according to the Arrhenius definition. a. HNO3(aq) b. NH4+(aq) d. HC2H3O2(aq)
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Ch.17 - Acids and Bases
Tro6th EditionChemistry: A Molecular ApproachISBN: 9780137832217
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TOC.tableOfContents
- Ch.1 - Matter, Measurement & Problem Solving118
- Ch.2 - Atoms & Elements106
- Ch.3 - Molecules and Compounds131
- Ch.4 - Chemical Reactions and Chemical Quantities56
- Ch.5 - Introduction to Solutions and Aqueous Solutions82
- Ch.6 - Gases114
- Ch.7 - Thermochemistry96
- Ch.8 - The Quantum-Mechanical Model of the Atom60
- Ch.9 - Periodic Properties of the Elements90
- Ch.10 - Chemical Bonding I: The Lewis Model89
- Ch.11 - Chemical Bonding II: Molecular Shapes, VSEPR & MO Theory85
- Ch.12 - Liquids, Solids & Intermolecular Forces51
- Ch.13 - Solids & Modern Materials47
- Ch.14 - Solutions90
- Ch.15 - Chemical Kinetics115
- Ch.16 - Chemical Equilibrium68
- Ch.17 - Acids and Bases136
- Ch.18 - Aqueous Ionic Equilibrium153
- Ch.19 - Free Energy & Thermodynamics93
- Ch.20 - Electrochemistry106
- Ch.21 - Radioactivity & Nuclear Chemistry74
- Ch.22 - Organic Chemistry140
Tro6th EditionChemistry: A Molecular ApproachISBN: 9780137832217Non è quello che usi tu?Cambia libro di testo
Capitolo 17, Problema 15
A solution of 0.23 mol of the chloride salt of protonated quinine (QH+), a weak organic base, in 1.0 L of solution has a pH of 4.58. What is the Kb of quinine (Q)?
Guida verificata passo dopo passo1
Identify the given information: the concentration of QH+ is 0.23 M, and the pH of the solution is 4.58.
Calculate the concentration of H+ ions using the pH value: \([H^+] = 10^{-pH}\).
Determine the concentration of OH- ions using the relationship \([OH^-] = \frac{K_w}{[H^+]}\), where \(K_w = 1.0 \times 10^{-14}\) at 25°C.
Set up the equilibrium expression for the dissociation of QH+ in water: \(QH^+ \rightleftharpoons Q + H^+\).
Use the expression for the base dissociation constant \(K_b = \frac{[Q][OH^-]}{[QH^+]}\) to solve for \(K_b\), using the concentrations of \([OH^-]\) and \([QH^+]\) at equilibrium.
Concetti chiave
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Weak Bases and Their Ionization
Weak bases, like quinine (Q), do not fully ionize in solution. Instead, they establish an equilibrium between the base and its conjugate acid when dissolved in water. The degree of ionization is characterized by the base dissociation constant (Kb), which quantifies the strength of the base in terms of its ability to accept protons.
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Percorso guidato
01:00
Calculating Percent Ionization of Weak Bases
pH and pOH Relationship
pH is a measure of the hydrogen ion concentration in a solution, indicating its acidity or basicity. The relationship between pH and pOH is given by the equation pH + pOH = 14 at 25°C. In this case, knowing the pH allows us to calculate the pOH, which is essential for determining the concentration of hydroxide ions in the solution, a key factor in calculating Kb.
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Percorso guidato
02:09pH and pOH Calculations
Equilibrium Expressions and Kb Calculation
The Kb of a weak base is derived from its equilibrium expression, which relates the concentrations of the products and reactants at equilibrium. For the dissociation of a weak base, Kb = [BH+][OH-] / [B], where [B] is the concentration of the base, [BH+] is the concentration of the conjugate acid, and [OH-] is the concentration of hydroxide ions. This relationship is crucial for calculating Kb from the given pH.
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Percorso guidato
03:20Equilibrium Constant Expressions