Skip to main content
Ch.17 - Acids and Bases
Tro - Chemistry: A Molecular Approach 6th Edition
Tro6th EditionChemistry: A Molecular ApproachISBN: 9780137832217Non è quello che usi tu?Cambia libro di testo
Tutti i libri di testoTro 6th EditionCh.17 - Acids and BasesProblema 98
Capitolo 17, Problema 98

A 0.135 M solution of a weak base has a pH of 11.23. Determine Kb for the base.

Guida verificata passo dopo passo
1
Identify the relationship between pH and pOH: \( \text{pH} + \text{pOH} = 14 \). Use this to find pOH from the given pH.
Calculate the hydroxide ion concentration \([\text{OH}^-]\) using the formula \([\text{OH}^-] = 10^{-\text{pOH}}\).
Set up the expression for the base dissociation constant \(K_b\) using the formula \(K_b = \frac{[\text{OH}^-]^2}{[\text{Base}] - [\text{OH}^-]}\).
Assume that \([\text{Base}] - [\text{OH}^-] \approx [\text{Base}]\) if \([\text{OH}^-]\) is much smaller than the initial concentration of the base.
Substitute the values into the \(K_b\) expression and solve for \(K_b\).

Concetti chiave

Ecco i concetti essenziali che devi comprendere per rispondere correttamente alla domanda.

Weak Base and pH

A weak base is a substance that partially ionizes in solution, establishing an equilibrium between the base and its ions. The pH of a solution indicates its acidity or basicity, with values above 7 being basic. In this case, a pH of 11.23 suggests that the solution is basic, and the concentration of hydroxide ions can be derived from the pH to help calculate the base's dissociation constant.
Video consigliato:
Percorso guidato
08:27
Calculating pH of Weak Bases Example

Equilibrium Constant (Kb)

The base dissociation constant (Kb) quantifies the strength of a weak base in solution. It is defined as the ratio of the concentration of the products (the ions formed) to the concentration of the reactants (the un-ionized base) at equilibrium. For a weak base, Kb can be calculated using the concentrations of the base and its ions at equilibrium, which can be derived from the pH and initial concentration.
Video consigliato:
Percorso guidato
01:14
Equilibrium Constant K

Relationship Between pH and pOH

The pH and pOH of a solution are related through the equation pH + pOH = 14 at 25°C. This relationship allows us to convert pH values into pOH values, which can then be used to find the concentration of hydroxide ions (OH-) in the solution. Knowing the concentration of OH- is essential for calculating Kb, as it directly relates to the degree of ionization of the weak base.
Video consigliato:
Percorso guidato
02:09
pH and pOH Calculations
Pratica correlata
Domanda del libro di testo

Caffeine (C8H10N4O2) is a weak base with a pKb of 10.4. Calculate the pH of a solution containing a caffeine concentration of 455 mg/L.

3290
views
4
rank
Domanda del libro di testo

Morphine is a weak base. A 0.150 M solution of morphine has a pH of 10.7. What is Kb for morphine?

3278
views
1
comments
Domanda del libro di testo

Determine the [OH–] and pH of a solution that is 0.140 M in F–.

1689
views
Domanda del libro di testo

Amphetamine (C9H13N) is a weak base with a pKb of 4.2. Calculate the pH of a solution containing an amphetamine concentration of 225 mg/L.

2435
views
Domanda del libro di testo

Determine if each anion acts as a weak base in solution. For those anions that are basic, write an equation that shows how the anion acts as a base. a. Br– b. ClO– c. CN– d. Cl–

1124
views
Domanda del libro di testo

Determine whether each anion is basic or neutral. For those anions that are basic, write an equation that shows how the anion acts as a base. c. NO3–

1244
views