Bài tập hoá vô cơ: axit và bazo

Chapter 14: Acids and Bases (CHEM 2B)
14.1 A research chemist adds a measured amount of HCl gas to pure water at 25°C and
obtains a solution with [H3O+] = 3.0 x 10-4M. Calculate [OH-]. Is the solution neutral
tral, acidic, or basic?
14.2 In an art restoration project, a conservator prepares copper-plate etching solutions
by diluting concentrated HNO3 to 2.0 M, 0.30 M, and 0.0063 M HNO3. Calculate
[H3O+], pH, [OH-], and pOH of the three solutions at 25°C.
14.3 Phenylacetic acid (C6H5CH2COOH, simplified here to HPAc) builds up in the blood
of persons with phenylketonuria, an inherited disorder that, if untreated, causes mental
retardation and death. A study of the acid shows that the pH of 0.12 M HPAc is 2.62.
What is the Ka of phenylacetic acid?
14.4 Propanoic acid (CH3CH2COOH, which we simplify as HPr) is a carboxylic acid
whose salts are used to retard mold growth in foods. What is the [H3O+] of 0.10 M HPr
(Ka = 1.3 x 10-5)?
14.5 Dimethylamine, (CH3)2NH, a key intermediate in detergent manufacture, has a Kb
of 5.9 x 10-4. What is the pH of 1.5M (CH3)2NH?
14.6 Sodium acetate (CH3COONa, or NaAc for this problem) has applications in
photographic development and textile dyeing. What is the pH of 0.25 M NaAc? Ka of
acetic acid (HAc) is l.8 x 10-5.
14.7 A 0.15 M solution of butanoic acid, CH3CH2CH2COOH, contains 1.51 x 10-3 M
H3O+. What is the Ka of butanoic acid?
14.8 Nitrous acid, HNO2, has a Ka of 7.1 x 10-4. What are [H3O+], [NO2-], and [OH-] in
0.50 M HNO2?
14.9 Chloroacetic acid, ClCH2COOH, has a pK of 2.87. What are [H3O+], pH,
[ClCH2COO-], and [ClCH2COOH] in 1.05 M ClCH2COOH?
Nguyen Tien Thao, Faculty of Chemistry, Hanoi College of Science, VNU
19 - Le Thanh Tong, Hoan Kiem, Hanoi, Vietnam. Email:

1

14.10 In a 0.25 M solution, a weak acid is 3.0% dissociated. (a) Calculate the [H3O+],
pH, [OH-], and pOH of the solution. (b) Calculate Ka of the acid.
14.11 The weak acid HZ has a Ka of 1.55 x10-4.
(a) Calculate the pH of 0.075 M HZ. (b) Calculate the pOH of 0.045 M HZ.
14.12 Fonnic acid, HCOOH, the simplest carboxylic acid, has many uses in the textile
and rubber industries. It is an extremely caustic liquid that is secreted as a defense by
many species of ants (family Formicidae). Calculate the percent dissociation of 0.50M
HCOOH.
14.13 Sodium hypochlorite solution, sold as "chlorine bleach," is recognized as a
potentially dangerous household product. The dangers arise from its basicity and from
ClO-, the active bleaching ingredient. What is [OH-] in an aqueous solution that is 5.0%
NaClO by mass? What is the pH of the solution? (Assume d of solution = 1.0 g/mL.)
14.14 The Ka values for acetic acid and hydrofluoric acid are 1.8 x10-5 and 7.2x10-4,
respectively. What are their pKa values?
14.15 Calculate the concentrations of all species present in 0.100 M H3PO4.
14.16 Calculate concentrations of all species present in 0.10 M H2SO4. Ka2 = 1.2 x 10-2.
14.17 Calculate [OH-], pH, and the percent hydrolysis for 0.10 M solutions of (a) sodium
acetate, NaCH3COO, and (b) sodium cyanide, NaCN. Both NaCH3COO and NaCN are
soluble ionic salts that are completely dissociated in H2O. Kb for CH3COO- = 5.6x10--10;
Kb for CN- = 2.5x10-5.
14.18 Calculate the pH of a 0.20 M solution of ammonium nitrate, NH4NO3. Ka for NH4+
= 5.6x10-10.
14.19 Calculate the pH and percent hydrolysis in 0.10 M AlCl3 solution. Ka =1.2x10-5 for
[Al(OH2)6]3+ (often abbreviated Al3+)
Additional problems:
Chapter 14: 49, 51, 53, 55, 57, 59, 61, 63, 65, 67, 69, 71, 73, 75, 77, 81, 83, 85, 87
All students must complete at leat ….%, Deadline: …

Nguyen Tien Thao, Faculty of Chemistry, Hanoi College of Science, VNU
19 - Le Thanh Tong, Hoan Kiem, Hanoi, Vietnam. Email:

2