A weak acid is titrated with a strong base and the pH is measured at each...

A weak acid is titrated with a strong base and the pH is measured at each interval. It the equivalence point is reached when 30 mL of the base has been added, describe how the pKa of the acid can be determined.

Solutions

Expert Solution

The method is described for any general monoprotic acid HA
dissociation of weak acid ---
HA H⁺ + A^-
dissociation constant of HA , Ka = [H⁺][A^-]/[HA]
when concentrations of both HA and A^- are equal then Ka = [H⁺]
this is also revealed by the henderson equation.
so pH = pKa when weak acid and it's conjugate base concetrations are same.This occurs at half equivalence point. For the given problem half equivalence volume of NaOH is 15 ml. so the pH value corresponding to 15 ml is noted from the plot , Which is pKa value of the given weak acid.
Multi protic acids dissociations also can be studied by the same method.

queen_honey_blossom answered 1 year ago

Next > < Previous

Related Solutions

classify each substance as a strong acid , weak acid , strong base or weak base...

classify each substance as a strong acid , weak acid , strong base or weak base KOH, Ca(OH)2, H 2SO4, HI, HCOOH, NaOH, HCN, C5H5N

Classify each substance as a strong acid , weak acid strong base or weak base for...

Classify each substance as a strong acid , weak acid strong base or weak base for the following compounds HI C5H5N NaOO HCOOH KOH Ca(OH)2 H2SO4 HCN

What is the pH of a weak acid strong base titration after each of the following...

What is the pH of a weak acid strong base titration after each of the following additions? Ka for HF is 3.5 x 10-4. a. 10.0 mL of 0.250 M NaOH added to 15.0 mL of 0.400 M HF b. 25.0 mL of 0.250 M NaOH added to 35.0 mL of 0.1785 M HF c. 20.0 mL of 0.250 M NaOH added to 20.0 mL of 0.350 M HF Please show your work so I can better understand this. thanks!...

Consider a monoprotic weak acid (HA) that is titrated with a strong base. What is the...

Consider a monoprotic weak acid (HA) that is titrated with a strong base. What is the relationship between the strength of the weak acid and the pH of the solution at the equivalence point? There is no relationship between the strength of the acid and the pH at the equivalence point. The pH at the equivalence point is always 7 in an acid base titration. The weaker the acid, the higher the pH at the equivalence point. The stronger the...

When a weak acid (HA) is titrated with NaOH (a strong base), (a) what species...

When a weak acid (HA) is titrated with NaOH (a strong base), (a) what species are present in the weak acid solution before the titration is started? (b) what species is/are decreasing during the titration? (c) what species is/are increasing during the titration? (d) what species is/are not involved in the reaction? (e) what is meant by the equivalence point? (f) what important species concentration increases after the equivalence point?

A 25.0 mL of a weak acid is titrated with a strong base (0.1 M). Calculate...

A 25.0 mL of a weak acid is titrated with a strong base (0.1 M). Calculate the pH of the solution during the titration if the weak acid concentration is 0.10 M and its Ka = 1.8 x 10-5 and 10.0 mL of base has been added. (Hint: use Henderson-Hasselbach equation). a) pH = 4.56 b) pH= 5.28 c) pH= 4.74

An acid with a Ka= 0.000343, is titrated with a strong base, what would the pH...

An acid with a Ka= 0.000343, is titrated with a strong base, what would the pH be after half the volume of base needed to reach the equivalenc point has been added?

Classify each titration curve as representing a strong acid titrated with a strong base

Classify each titration curve as representing a strong acid titrated with a strong base, a strong base titrated with a strong acid, a weak acid titrated with a strong base, a weak base titrated with a strong acid, or a polyprotic acid titrated with a strong base. Calculate the pH of the resulting solution if 20.0 mL of 0.200 M HCl(aq) is added to 30.0 mL of 0.200 M NaOH(aq). pH = Calculate the pH of the resulting solution if 20.0 mL...

Weak Acid - Strong Base Titration Calculate the pH at the given amounts below in the...

Weak Acid - Strong Base Titration Calculate the pH at the given amounts below in the titration. You are titrating 35.0 mL of .15 M HNO2 with .1 M NaOH until you reach 100 mL of NaOH added. For this problem the Ka value is 4.6 x 10-4 a) 0.00 mL NaOH added b) 30.0 mL NaOH added c) 60.0 mL NaOH added d) 100.0 mL NaOH added

What is the approximate pH at the equivalence point of a weak acid-strong base titration if...

What is the approximate pH at the equivalence point of a weak acid-strong base titration if 25 mL 21) of aqueous formic acid requires 29.80 mL of 0.0567 M NaOH? Ka =1.8 × 10-4 for formic acid. A) 2.46 B) 8.12 C) 11.54 D) 5.88

Subjects