Question

Which of the statements below is/are true of your solution at equivalence? Select all true statements below. The concentration of acetate ions (CH2C00) at equivalence is the same as the original concentration of acetic acid (CH2COOH) at the start of the titration (i.e. 1.0 M). The number of moles of acetate ions (CH3COO") at equivalence is the same as the number of moles of of acetic acid (CH2COOH) at the start of the titration (i.e. 0.10 mol). At the equivalence point, there are equal numbers of moles of acetate ions (CH3C00“) and acetic acid (CH3COOH) in solution. At the equivalence point, a small amount of acetic acid (CH3COOH) will be present in solution since acetate (CH3COO") is a weak base. At the equivalence point, there is absolutely no acetic acid (CH3COOH) present in solution since all of it reacted.

Answer 1

True statements are :

(1.) The number of moles of acetate ions (CH₃COO^-) at equivalence is the same as the number of moles of acetic acid (CH₃COOH) at the start of the titration (i.e. 0.10 mol).

(2.) At the equivalence point, a small amount of acetic acid (CH₃COOH) will be present in solution since acetate (CH₃COO^-) is a weak base.

Explanation

The neutralization equation of acetic acid and NaOH is

CH₃COOH (aq) + NaOH (aq) $\rightarrow$ CH₃COO^- (aq) + Na⁺ (aq) + H₂O (l)

moles acetate ions produced = moles acetic acid reacted

At equivalence point, all acetic acid is neutralized to acetate ions.

Since acetate is a weak base, it hydrolyzes to give acetic acid and hydroxide ions

CH₃COO^- (aq) + H₂O (l) $\rightarrow$ CH₃COOH (aq) + OH^-(aq)