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: nguyentienthao@gmail.com 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: nguyentienthao@gmail.com