Which of the following is/are true regarding a 0.10 M...

Which of the following is/are true regarding a 0.10 M solution of a weak base, $\mathrm{B}^{-}$? (a) $[\mathrm{HB}]=0.10 \mathrm{M}$ (b) $\left[\mathrm{OH}^{-}\right]=[\mathrm{HB}]$ (c) $\left[\mathrm{B}^{-}\right]>[\mathrm{HB}]$ (d) $\left[\mathrm{H}^{+}\right]=\frac{1.0 \times 10^{-14}}{0.10}$ (e) $\mathrm{pH}=13.0$

Which of the following is/are true regarding a 0.10 M solution of a weak base, $\mathrm{B}^{-}$?
(a) $[\mathrm{HB}]=0.10 \mathrm{M}$
(b) $\left[\mathrm{OH}^{-}\right]=[\mathrm{HB}]$
(c) $\left[\mathrm{B}^{-}\right]>[\mathrm{HB}]$
(d) $\left[\mathrm{H}^{+}\right]=\frac{1.0 \times 10^{-14}}{0.10}$
(e) $\mathrm{pH}=13.0$

Key Concepts

Weak Base Equilibrium

Weak bases do not completely dissociate in aqueous solution. Instead, they establish a dynamic equilibrium in which the base reacts with water to form its conjugate acid and hydroxide ions. This concept underpins the understanding of how weak bases behave in solution, differentiating them from strong bases that fully ionize.

Hydrolysis Reaction

In aqueous solution, a weak base often undergoes a hydrolysis reaction with water, forming its conjugate acid and hydroxide ions in a one-to-one ratio. This reaction is key to predicting the relative amounts of species present in solution, as the equilibrium favors only partial conversion of the original base.

Equilibrium Concentration Relationships

Because the hydrolysis of a weak base produces products in a 1:1 molar ratio, the concentrations of the conjugate acid and hydroxide ions are approximately equal at equilibrium. Furthermore, since only a small fraction of the weak base reacts, the concentration of the unreacted base remains higher than that of the product, an insight that is critical when analyzing the composition of weak base solutions.

Relationship between pH, pOH, and the Water Ion Product (Kw)

The connection between the concentrations of hydroxide ions and hydrogen ions in any aqueous solution is governed by the ion product constant of water (Kw). This relationship, often used to calculate pH and pOH, is fundamental to acid-base chemistry and helps in determining the overall basicity of a solution from the concentration of hydroxide ions generated during hydrolysis.

Transcript

Please give Ace some feedback