Indietro
- Which of the following mixtures has the highest pH? (a) Equal volumes of 1.0 M HCl and 1.0 M NaOH (b) Equal volumes of 0.1 M HNO3 and 0.1 M KOH (c) Equal volumes of 0.1 M HCN and 0.1 M NaOH (d) Equal volumes of 0.1 M NaF and 0.1 M HCl
Problema 1
- What is the percent dissociation in a solution that is 0.50 M in acetic acid (CH3CO2H) and 0.10 M in sodium acetate (NaCH3CO2)? (Ka = 1.8 x 10^-5) (a) 0.018% (b) 0.090% (c) 7.2 x 10^-3% (d) 2.3%
Problema 2
- A 1.00 L buffer solution is 0.250 M in HF and 0.250 M in NaF. Calculate the pH of the solution after the addition of 100.0 mL of 1.00 M HCl. (Ka = 3.5 x 10^-4) (a) 4.11 (b) 3.82 (c) 3.46 (d) 3.09
Problema 3
- What is the pH of a buffer solution prepared by dissolving 0.250 mol of NaH2PO4 and 0.075 mol of NaOH in enough water to make 1.00 L of solution? (Ka (H2PO4-) = 6.2 X 10^-8) (a) 6.32 (b) 6.83 (c) 7.21 (d) 7.71
Problema 4
- Which is the best acid-base pair to use in the preparation of a buffer with pH = 10.5? (a) HOI and OI- (Ka = 2.0 x 10^-11) (b) HNO2 and NO2- (Ka = 4.5 x 10^-4) (c) HIO3 and IO3- (Ka = 1.7 x 10^-1) (d) H2PO4^- and HPO4^2- (Ka = 6.2 x 10^-8)
Problema 5
- Calculate the concentrations of NH4+ and NH3 and the pH in a solution prepared by mixing 20.0 g of NaOH and 0.500 L of 1.5 M NH4Cl. Assume that the volume remains constant.
Problema 8
- A 25.00 mL sample of 1.00 M CH3CO2H is titrated with 1.00 M NaOH. Calculate the pH after 30.00 mL of NaOH has been added. (Ka = 1.8 x 10^-5) (a) 6.90 (b) 9.36 (c) 11.54 (d) 12.95
Problema 9
- The pH titration curve applies to the titration of 40.0 mL of a 0.100 M solution of an acid with 0.100 M NaOH. What are the approximate pKa values for this acid?
Problema 11
(a) pKa1 = 5, pKa2 = 10 (b) pKa1 = 7, pKa2 = 11 (c) pKa1 = 5, pKa2 = 10, pKa3 = 13 (d) pKa1 = 5, pKa2 = 7, pKa3 = 10
- What is the solubility-constant expression for Ca3(PO4)2 (s)? (a) [Ca2+]3 [PO43-]2 (b) [Ca2+]3 [PO43-]2 / [Ca3(PO4)2] (c) [Ca(PO4)2] / [Ca2+]3 [PO43-]2 (d) [Ca2+]2 [PO43-]3
Problema 12
- What is the molar solubility of Ag2SO3 in water? The solubility-product constant for silver sulfite is 1.5 x 10^-14 at 25 °C. (a) 1.2 x 10^-7 M (b) 2.0 x 10^-5 M (c) 8.7 x 10^-8 M (d) 1.6 x 10^-5 M
Problema 13
- Consider a saturated solution of the slightly soluble salt BaCO3. Adding which of the following substances will increase the solubility? (a) HNO3 (b) Na2CO3 (c) Ba(NO3)2 (d) KOH
Problema 14
- What is the molar solubility of BaF2 in a solution containing 0.0750 M LiF (Ksp = 1.7 x 10^-6) (a) 2.3 x 10^-5 M (b) 3.0 x 10^-4 M (c) 1.2 x 10^-2 M (d) 1.3 x 10^-3 M
Problema 15
- What is the molar solubility of AgI in 0.20 M NaCN? (a) 6.2 x 10^-4 M (b) 1.0 x 10^-1 M (c) 7.6 x 10^-2 M (d) 2.1 x 10^-3 M
Problema 17
- A solution containing sulfide ions is added to a solution of 0.036 M Cu2+ and 0.044 M Fe2+. At what concentration of sulfide ion will a precipitate begin to form? What is the identity of the precipitate? (a) 1.4 x 10^-16 M, FeS (b) 3.6 x 10^-35 M, CuS (c) 3.6 x 10^-35 M, FeS (d) 1.4 x 10^-16 M, C
Problema 18
- Consider the following table of standard reduction potentials:
Problema 35
(b) Which substances can be oxidized by B2+? Which can be reduced by D?
Problema 38
The strong acid HA is mixed with an equal molar amount of aqueous NaOH. Which of the following pictures represents the equilibrium state of the solution? (Na+ ions and solvent water molecules have been omitted for clarity.)
(A) (B) (C) (D)
- The following pictures represent initial concentrations in solutions that contain a weak acid HA (pKa = 6.0) and its sodium salt NaA. (Na+ ions and solvent water molecules have been omitted for clarity.)
Problema 39
. (c) Draw a picture that represents the equilibrium state of solution (1) after the addition of two OH-ions.
Problema 39b
The following pictures represent initial concentrations in solutions that contain a weak acid HA (pKa = 6.0) and its sodium salt NaA. (Na+ ions and solvent water molecules have been omitted for clarity.)
. (b) Draw a picture that represents the equilibrium state of solution (1) after the addition of two H3O+ ions.
Problema 40a
The following pictures represent solutions that contain one or more of the compounds H2A, NaHA, and Na2A, where H2A is a weak diprotic acid. (Na+ ions and solvent water molecules have been omitted for clarity.)
(a) Which of the solutions are buffer solutions?
Problema 40b
The following pictures represent solutions that contain one or more of the compounds H2A, NaHA, and Na2A, where H2A is a weak diprotic acid. (Na+ ions and solvent water molecules have been omitted for clarity.)
(b) Which solution has the greatest buffer capacity?
Problema 41a
The following plot shows two pH titration curves, each representing the titration of 50.0 mL of 0.100 M acid with 0.100 M NaOH:
. (a) Which of the two curves represents the titration of a strong acid? Which represents a weak acid?
Problema 41b
The following plot shows two pH titration curves, each representing the titration of 50.0 mL of 0.100 M acid with 0.100 M NaOH:
. (b) What is the approximate pH at the equivalence point for each of the acids?
Problema 41c
The following plot shows two pH titration curves, each representing the titration of 50.0 mL of 0.100 M acid with 0.100 M NaOH:
. (c) What is the approximate pKa of the weak acid?
Problema 42a
The following pictures represent solutions at various stages in the titration of a weak base B with aqueous HCl. (Cl- ions and solvent water molecules have been omitted for clarity.)
. (a) To which of the following stages do solutions 1–4 correspond? (i) The initial solution before addition of any HCl (ii) Halfway to the equivalence point (iii) At the equivalence point (iv) Beyond the equivalence point
Problema 42b
The following pictures represent solutions at various stages in the titration of a weak base B with aqueous HCl. (Cl- ions and solvent water molecules have been omitted for clarity.)
. (b) Is the pH at the equivalence point more or less than 7?
- The following pictures represent solutions at various stages in the titration of a weak diprotic acid H2A with aqueous NaOH. (Na+ ions and water molecules have been omitted for clarity.)
Problema 43
. (b) Which solution has the highest pH? Which has the lowest pH?
Problema 44a
The following pictures represent solutions at various stages in the titration of sulfuric acid H2A (A2- = SO4 2-) with aqueous NaOH. (Na+ ions and water molecules have been omitted for clarity.)
. (a) To which of the following stages do solutions 1–4 correspond? (i) Halfway to the first equivalence point (ii) Halfway between the first and second equivalence points (iii) At the second equivalence point (iv) Beyond the second equivalence point
Problema 44b
The following pictures represent solutions at various stages in the titration of sulfuric acid H2A (A2- = SO4 2-) with aqueous NaOH. (Na+ ions and water molecules have been omitted for clarity.)
. (b) Which solution has the highest pH? Draw a picture that represents the solution prior to addition of any NaOH.
Problema 46
The following pictures represent solutions of Ag2CrO4, which also may contain ions other than Ag+ and CrO42- that are not shown. Solution 1 is in equilibrium with solid Ag2CrO4. Will a precipitate of solid Ag2CrO4 form in solutions 2-4? Explain.
(1) (2) (3) (4)
- Is the pH greater than, equal to, or less than 7 after the neutralization of each of the following pairs of acids and bases? (c) HBr and aniline (C6H5NH2)
Problema 47