Question

which statement explains the ph at the equivalence point for this titration?

• the ph is less than 7 because the conjugate acid goes through hydrolysis forming an acidic salt.
• the ph will be less than 2 because the strong acid fully dissociates.
• the ph is 7 because it is a neutralization reaction and 7 is neutral.
• the ph is more than 7 because the conjugate base goes through hydrolysis forming a basic salt.

Explanation:

Analyze the titration curve

Using the Titration Curves knowledge point

• The initial pH is high (around 11), indicating a weak base analyte.
• As acid is added, the pH decreases, showing a steep drop around pH 5.
• The equivalence point is located at the center of this steep vertical region, which is below 7 (approximately pH 5).

Determine the chemical species

Using the Equivalence Point pH knowledge point

• Titrating a weak base with a strong acid produces its conjugate acid at the equivalence point.
• The conjugate acid undergoes hydrolysis with water:

$$ \text{BH}^+ + \text{H}_2\text{O} ightleftharpoons \text{B} + \text{H}_3\text{O}^+ $$

• This hydrolysis produces hydronium ions, resulting in an acidic solution (\(\text{pH} < 7\)).

Answer:

• The pH is less than 7 because the conjugate acid goes through hydrolysis forming an acidic salt. (Correct answer)
• The pH will be less than 2 because the strong acid fully dissociates.
• The pH is 7 because it is a neutralization reaction and 7 is neutral.
• The pH is more than 7 because the conjugate base goes through hydrolysis forming a basic salt.