Question

What is the pH at the equivalence point in the titration of a 20.9 mL sample of a 0.479M aqueous hydrofluoric acid solution with a 0.313M aqueous sodium hydroxide solution?

Answer 1

The pH at the equivalence point in the titration of hydrofluoric acid with sodium hydroxide is 7.00.

Step-by-step explanation:

In a titration, the equivalence point is the point at which the number of moles of acid and base are equal. For the titration of a strong acid with a strong base, such as in the case of hydrofluoric acid and sodium hydroxide, the equivalence point occurs at a pH of 7.00.

It's important to note that this information is specific to the titration of a strong acid with a strong base. The pH at the equivalence point can be different for other acid-base titrations.

Answer 2

The pH at the equivalence point in the titration of the hydrofluoric acid (HF) solution with sodium hydroxide (NaOH) is approximately 7.

At the equivalence point, the moles of acid (HF) equal the moles of base (NaOH), leading to the formation of water and sodium fluoride (NaF). The balanced equation is:

HF + NaOH — NaF + H₂O

Sodium fluoride is a salt, and its aqueous solution undergoes hydrolysis. The fluoride ion (F⁻) reacts with water to form hydrofluoric acid (HF) and hydroxide ions (OH⁻):

F⁻ + H₂O ⇌HF + OH⁻

The hydrolysis of sodium fluoride results in the production of hydroxide ions, causing the solution to be slightly basic. The pH at the equivalence point is around 7, indicating neutrality.

In summary, the pH at the equivalence point is approximately 7 due to the hydrolysis of the salt formed from the neutralization reaction, resulting in a slightly basic solution.