Final answer:
The pH at the equivalence point for the titration of a weak acid (nitrous acid) with a strong base (sodium hydroxide) will be above 7, indicating a basic solution. To find the exact pH, we would need to calculate using the acid dissociation constant (Ka) for nitrous acid or use direct experimental data, which is not provided.
Step-by-step explanation:
The pH at the equivalence point in the titration of a 23.1 mL sample of a 0.377 M aqueous nitrous acid (a weak acid) with a 0.329 M aqueous sodium hydroxide solution (a strong base) can be determined using the concept of acid-base neutralization. From the given data, similar titrations show that the equivalence point pH for a weak acid titrated with a strong base is greater than 7. However, to find the exact pH at the equivalence point for the titration of nitrous acid and sodium hydroxide, we would use the following stoichiometric relationship: moles of HNO2 = moles of NaOH.
First, we find the moles of nitrous acid (HNO2):
moles HNO2 = volume × molarity = 0.0231 L × 0.377 mol/L = 0.0087077 mol
Next, using the molar equivalence, moles NaOH required to reach equivalence point = moles HNO2, we find the volume of NaOH required:
volume NaOH = moles NaOH / molarity NaOH = 0.0087077 mol / 0.329 M = 0.0264652 L or 26.4652 mL
Since nitrous acid is a weak acid, its conjugate base formed on reaction with NaOH partially ionizes in water, resulting in a basic solution at the equivalence point. Hence, the pH is greater than 7 but without additional information such as the acid dissociation constant (Ka) for nitrous acid or direct experimental data, the exact numerical pH value cannot be specified.