Fifty cm^3 of 1.000 M nitrous acid is titrated with 0.850 M NaOH. What is the pH of the solution

step 1 So this problem is a pretty straightforward titration with a, you start with a one molar solutio

Fifty cm^3 of 1.000 M nitrous acid is titrated with 0.850 M...

Fifty $\mathrm{cm}^{3}$ of $1.000 \mathrm{M}$ nitrous acid is titrated with $0.850 \mathrm{M} \mathrm{NaOH}$. What is the $\mathrm{pH}$ of the solution (a) before any $\mathrm{Na} \mathrm{OH}$ is added? (b) at half-neutralization? (c) at the equivalence point? (d) when $0.10 \mathrm{~mL}$ less than the volume of $\mathrm{NaOH}$ to reach the equivalence point is added? (e) when $0.10 \mathrm{~mL}$ more than the volume of $\mathrm{NaOH}$ to reach the equivalence point is added? (f) Use your data to construct a plot similar to that shown in Figure 14.6 (pH versus volume $\mathrm{Na} \mathrm{OH}$ added $)$

Fifty $\mathrm{cm}^{3}$ of $1.000 \mathrm{M}$ nitrous acid is titrated with $0.850 \mathrm{M} \mathrm{NaOH}$. What
is the $\mathrm{pH}$ of the solution
(a) before any $\mathrm{Na} \mathrm{OH}$ is added?
(b) at half-neutralization?
(c) at the equivalence point?
(d) when $0.10 \mathrm{~mL}$ less than the volume of $\mathrm{NaOH}$ to reach the equivalence point is added?
(e) when $0.10 \mathrm{~mL}$ more than the volume of $\mathrm{NaOH}$ to reach the equivalence point is added?
(f) Use your data to construct a plot similar to that shown in Figure 14.6 (pH versus volume $\mathrm{Na} \mathrm{OH}$ added $)$

Key Concepts

Henderson–Hasselbalch Equation

The Henderson–Hasselbalch equation is used to estimate the pH of buffer solutions. In titrations involving a weak acid and its conjugate base, especially at the half-equivalence point, this equation simplifies pH calculation by relating the pH directly to the pKa of the weak acid and the ratio of the concentrations of the conjugate base to the acid.

Titration Curves

A titration curve is a graph of pH versus the volume of titrant added during a titration. It visually represents the different stages of the reaction, including the initial pH, the buffer region, the steep rise near the equivalence point, and the behavior of the system when the titrant is added in excess. This plot is a crucial tool for analyzing the titration process and extracting key parameters such as the equivalence point.

Equivalence Point

The equivalence point in a titration is reached when the number of moles of titrant added exactly equals the number of moles of the analyte (acid or base) present in the solution. For weak acid–strong base titrations, the pH at the equivalence point is influenced by the conjugate base, which typically results in a pH greater than 7.

Acid?Base Titration

Acid?base titration is an analytical technique used to determine the concentration of an acid or a base by gradually adding a titrant (a solution of known concentration) until the reaction reaches completion. This process involves monitoring changes in pH as the titrant is added, which helps identify key stages of the reaction such as the initial pH, buffer region, and equivalence point.

Buffer System

A buffer system is a solution that resists changes in pH when small amounts of acid or base are added. In the context of titration, when a weak acid is only partially neutralized, its conjugate base is present along with some of the remaining acid, forming a buffer. This is especially evident at the half-neutralization (half-equivalence) point.

Half-Neutralization (Half-Equivalence) Point

The half-neutralization point occurs during the titration of a weak acid with a strong base when exactly half of the acid has been converted to its conjugate base. At this stage, the concentrations of the acid and its conjugate base are equal, and the pH can be directly related to the acid's dissociation constant using specific equations.

Weak Acid–Strong Base Titration

In a weak acid–strong base titration, the weak acid reacts with the strong base to form its conjugate base. The reaction's progress can be tracked by the gradual change of pH, where a buffer is initially formed, then complete neutralization occurs at the equivalence point, and finally a rise in pH is observed when the titrant is in excess.

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