Acid-dissociation constants of two acids are listed in the table above. A 20. mL sample of a 0.10 M solution of each acid is titrated to the equivalence point with 20. mL of 0.10 M NaOH. Which of the following is a true statement about the pH of the solutions at the equivalence point? (A) Solution I has a higher pH at the equivalence point because CH_3CO_2H is the stronger acid. (B) Solution 1 has a higher pH at the equivalence point because CH_3CO_2H has the stronger conjugate base. (C) Solution 1 has a lower pH at the equivalence point because CH_3CO_2H is the stronger acid.(D) Solution 1 has a lower pH at the equivalence point because CH_3CO_2H is the Conjugate base.

Incomplete question, missing the table. See explanation

Acid-dissociation constants of two acids are listed in the table above. A 20. mL sample of a 0.10 M solution of each acid is titrated to the equivalence point with 20. mL of 0.10 M NaOH. Which of the following is a true statement about the pH of the solutions at the equivalence point? (A) Solution I has a higher pH at the equivalence point because CH_3CO_2H is the stronger acid. (B) Solution 1 has a higher pH at the equivalence point because CH_3CO_2H has the stronger conjugate base. (C) Solution 1 has a lower pH at the equivalence point because CH_3CO_2H is the stronger acid.(D) Solution 1 has a lower pH at the equivalence point because CH_3CO_2H is the Conjugate base.

Answer (B) is a true statement

Explanation:

Incomplete question: the table for the two acids is missing. An online search revealed the data missing from Chegg ( see attachment )

The equilibria for the two acids are:

CH₃COOH ⇄ CH3COO⁻ + H₃O⁺   Ka = 1.75 x 10⁻⁵

CF₃COOH ⇄ CF₃COO⁻  + H₃O⁺   Ka = 1.0 x 10⁰

The concentrations and volumes of the acids are the same so to answer the question we have to look for the respective strength of their equilibria.

(A) This statement is false since Ka for CH₃COOH is smaller than Ka for CF₃COOH, therefore CF₃COOH is a stronger acid than CH₃COOH

(B) This statement is true since the conjugate base for the weak acetic acid is  CH3COO⁻  which undergoes further hydrolysis at the equivalence point according to the equilibria:

CH₃COO⁻ + H₂O ⇄ CH₃COOH + OH⁻

with a kb = Kw/Ka = 10⁻¹⁴/1.75 x 10⁻⁵ = 5.71 x 10⁻¹⁰

For CF₃COO⁻ the hydrolysis reaction will be:

CF₃COO⁻ + H₂O  ⇄ CF₃COOH + OH⁻

Kb = 10⁻¹⁴/10⁰ = 10⁻¹⁴

Indeed Kb for the conjugate base of CF₃COOH is very small and the pH at the equivalence point will be that of water for all practical purposes while some CF₃COO⁻ will undergo hydrolysis according to its Kb making its pH higher at the equivalence point.

(C)  False statement, although the pH at the equivalence point for CF₃COOH is lower, CH₃COOH is not a stronger acid than CF₃COOH as we saw from the comparisons of their Kas.

(D) False since CH₃COOH is not a conjugate base and it does not have a lower pH at the equivalence point for the reasons stated in (B)

Answer (B) is a true statement

c is the answer because when something is left after something evaporates that shows the chemical change.

the answer would be c