Question

A student titrates 10.0 mL samples of 1.0M Solutions of each of the haloacetic acids with a standard solution of NaOH. Which of the following statements correctly predicts the volume of NaOH(aq) needed to reach the equivalence point? (A) Fluoroacetic acid will need the smallest volume of NaOH(aq) to reach the equivalence point. (B) Iodoacetic acid will need the smallest volume of NaOH(aq) to reach the equivalence point. (C) All of the acids will need the same volume of NaOH(aq) to reach the equivalence point. (D) All of the haloacetic acids are weak; therefore none will reach an equivalence point.

Answer 1

All of the 1.0M haloacetic acid solutions will need the same volume of NaOH to reach the equivalence point during titration, as one mole of base is required to neutralize one mole of any monoprotic acid.

Step-by-step explanation:

The student's question pertains to the volume of NaOH needed to reach the equivalence point when titrating 1.0M solutions of various haloacetic acids. The correct statement is that all of the haloacetic acids will require the same volume of NaOH to reach the equivalence point if they are present in the same concentrations and have the same molarity. This is because the stoichiometry of the reaction dictates that one mole of NaOH is required to neutralize one mole of any monoprotic acid, regardless of the identity of the halogen atom in the acid.

As titrations are based on stoichiometric relationships, the volume of NaOH needed for neutralization will be the same for equimolar solutions of each haloacetic acid in a monoprotic acid-base reaction. In other words, answer choice (C) is correct. Despite any differences in the strength of the haloacetic acids, they are all expected to reach an equivalence point when titrated with a strong base like NaOH, and since the acids are all 1.0M, the volume of NaOH will be the same.

Answer 2

All of the acids will need the same volume of NaOH(aq) to reach the equivalence point.

Step-by-step explanation:

The equivalence point of a weak acid-strong base titration is reached when only the conjugate base of the weak acid remains. Since all the weak acids use the same reaction equation, they would all use the same amount of NaOH to react with all the present weak acids.