Problem 1 What is the ph of a 291mL sample of 2.993M benzoic acid (C 6 H 5 COOH) (K a =6.4x10-5 )?
Problem 2 A 489mL sample of 0.5542M HNO 3 is mixed with 427mL sample of NaOH (which has a ph of 14.06). What is the ph of the resulting solution?
The K a values at 25 o C for a series of acids is given: 1.8 x 10-5 7.6 x 10-4 1.3 x 10-3 1.4 x 10-3 2.2 x 10-2 Which of the following acids has a K a = 1.4 x 10-3? Problem 3
Problem 4 Consider a solution containing 0.45M HCN and 0.69M NaCN for the next two questions. The K a for HCN = 6.2 x 10-10. What is the ph of this solution?
Problem 5 Consider a solution containing 0.45M HCN and 0.69M NaCN for the next two questions. The K a for HCN = 6.2 x 10-10. Now calculate the ph of this solution after 0.25 mol of NaOH is added to 1.00L of the solution. Assume that the volume does not change.
Problem 6 Consider a 7.3 x 10-10 M solution of HCl at 285 K. What is the ph of the solution?
Problem 7 For the following reaction, K < 1 at room temperature. HOCl (aq) + HCO 3 - (aq) H 2 CO 3 (aq) + OCl - (aq) Which of the following statements is true? A) H 2 CO 3 is a stronger acid than HOCl. B) HOCl is a stronger acid than H 2 CO 3. C) OCl - is a stronger acid than HOCl. D) HCO - 3 is stronger base than OCl -. E) More information is needed.
Problem 8 What is the ph of a solution that results from adding 0.081 mol Ca(OH) 2 (s) to 1.37L of a buffer comprised of 0.21M HF and 0.21M NaF?
Problem 9 A 0.251L solution of 1.89M sulfurous acid (K a1 = 1.5x10-2 and K a2 = 1.0x10-7 ) is titrated with 1.25M NaOH. What will the ph of the solution be when 0.6793L of the NaOH has been added?
Problem 9 A 0.251L solution of 1.89M sulfurous acid (K a1 = 1.5x10-2 and K a2 = 1.0x10-7 ) is titrated with 1.25M NaOH. What will the ph of the solution be when 0.6793L of the NaOH has been added?
Problem 10 The titration of 1.00L of a 1.00M solution of the triprotic acid, H 3 A, with 1.00M NaOH is shown below. It is not drawn to scale. What is the ph at D? H 3 A + H 2 O H 3 O + + H 2 A - K a1 =3.29x10-3 H 2 A - + H 2 O H 3 O + + HA 2- K a2 =6.43x10-7 HA 2- + H 2 O H 3 O + + A 3- K a3 =4.25x10-10
Problem 11 The titration of 1.00L of a 1.00M solution of the triprotic acid, H 3 A, with 1.00M NaOH is shown below. It is not drawn to scale. What is the ph at C? H 3 A + H 2 O H 3 O + + H 2 A - K a1 =3.29x10-3 H 2 A - + H 2 O H 3 O + + HA 2- K a2 =6.43x10-7 HA 2- + H 2 O H 3 O + + A 3- K a3 =4.25x10-10
Problem 12 Consider a 0.35M solution of each of the following salts in distilled water. Will the solution be acidic, neutral, or basic? You may need to reference a table of K a and K b Tables values.. NH 4 OBr: BaClO 4 : RbCH 3 COO: (CH 3 CH 2 ) 3 NHNO 2 :
Problem 13 How many of the following are true? 1. The buffer with the greatest buffering capacity for a phenol/sodium phenolate buffer system will have a ph of 9.60. 2. A buffer resists ph change when base is added by converting hydroxide ions to hydronium ions.. 3. A buffered system can be formed by combining a weak acid/conjugate base pair in solution. 4. A buffer is formed when you add HCl to NH 3. 5. A buffer is formed when you add HCl to CH 3 COOH.
Problem 14 Which of the following solutions will produce a buffer with ph near 10.50? 1. 1.00L of 0.50M HSO 4 - (K a = 1.0x10-7 ) + 1.00L of 0.25M KOH. 2. 2.00L 0.50M H 2 NNH 2 (K b = 3.0x10-6 ) + 2.00L 0.25M HI. 3. 0.100L 1.00M H 3 BO 3 (K a = 5.8x10-10 ) + 0.020L 2.50M HBr. 4. 0.100L of 0.50M HONH 2 (K b = 1.1x10-8 ) + 0.50L of 0.050M HNO 3. 5. 0.500L 1.00M CH 3 NH 2 (K b = 4.4x10-4 ) + 1.00L 0.25M HI.
Problem 15 The next three problems deal with the titration of 145mL of 1.35M methylamine CH 3 NH 2 (K b = 4.4 x 10-4 ) with 0.25M HCl. Water will be a major species throughout the titration. The chemical species, in addition to water, that can be found in this reaction mixture during the titration are: I. H + II. OH - III. Cl - IV. CH 3 NH 2 V. CH 3 NH 3 + What is the ph at equivalence point?
Problem 15 The next three problems deal with the titration of 145mL of 1.35M methylamine CH 3 NH 2 (K b = 4.4 x 10-4 ) with 0.25M HCl. Water will be a major species throughout the titration. The chemical species, in addition to water, that can be found in this reaction mixture during the titration are: I. H + II. OH - III. Cl - IV. CH 3 NH 2 V. CH 3 NH 3 + What is the ph at equivalence point?
Problem 16 The next three problems deal with the titration of 145mL of 1.35M methylamine CH 3 NH 2 (K b = 4.4 x 10-4 ) with 0.25M HCl. Water will be a major species throughout the titration. The chemical species, in addition to water, that can be found in this reaction mixture during the titration are: I. H + II. OH - III. Cl - IV. CH 3 NH 2 V. CH 3 NH 3 + How many ml of HCl will need to be added to reach ph=10.64?
Problem 17 The next three problems deal with the titration of 145mL of 1.35M methylamine CH 3 NH 2 (K b = 4.4 x 10-4 ) with 0.25M HCl. Water will be a major species throughout the titration. The chemical species, in addition to water, that can be found in this reaction mixture during the titration are: I. H + II. OH - III. Cl - IV. CH 3 NH 2 V. CH 3 NH 3 + What are the major species when 783mL of HCl has been added?
Problem 18 A 0.613M solution of a weak acid has a ph of 2.670 at 309K. What is the K a of the weak acid?
Consider the following titration curve: Problem 19 How many of the following are true? 1. The ph at point B is pk a1. 2. The ph at point E will be the average of pk a1 and pk a2. 3. To the right of point F [A 3- ] > [HA 2- ]. 4. HA 2- will be a major species at point E. Which is based on the following reactions: H 3 A H + + H 2 A - H 2 A - H + + HA 2- HA 2- H + + A 3-5. The second dissociation of H + will play a large role in the ph level at point E.