Q&A Hero

Q: If 40 mL of 0.10 M NaOH is added to 50 mL of 0.20M HC2H3O2, what is the pH of the resulting solution at 25ºC? Ka for HC2H3O2 is 1.8x10-5 at 25ºC.A) 10.5B) 4.3C) 4.9D) 2.7E) 4.6

Q: A 75.0-mL sample of 0.0500 M HCN (Ka= 6.2 x10-10) is titrated with 0.421 M NaOH. What is [H+] in the solution after 3.0 mL of 0.421 M NaOH has been added?A) 8.2 x10-6MB) 2.0 MC) 1.2 x10-9MD) 1.0 x10-7ME) none of these

Q: A solution contains 10. mmol of H3PO4 and 5.0 mmol of NaH2PO4. How many milliliters of 0.10 M NaOH must be added to reach the second equivalence point of the titration of the H3PO4with NaOH?A) 250 mLB) 2.0 x102 mLC) 50 mLD) 150 mLE) 1.0 x102 mL

Q: Which of the following indicators is most suitable for the titration of a 25.00-mL sample of 0.140 Mpropionic acid, HC3H5O2, with strong base?A) alizarin yellow (transition pH range: 10.0-12.0)B) methyl red (transition pH range: 4.2-6.3)C) methyl orange (transition pH range: 3.1-4.4)D) thymol blue (transition pH range: 8.0-9.6)E) bromothymol blue (transition pH range: 6.2-7.6)

Q: What is the pH at the equivalence point of the titration of a strong acid with a strong base? A) 3.9 B) 4.5 C) 8.2 D) 7.0 E) none of these

Q: Which of the following statements is true concerning the titration of a weak monoprotic acid with a strong base? A) At the equivalence point, the solution has excess moles of strong base. B) At the equivalence point, the solution is acidic. C) At the equivalence point, the solution has excess moles of weak acid. D) At the equivalence point, the solution is composed of the conjugate base of the weak acid. E) At the equivalence point, the pH is 7.

Q: What is the hydronium-ion concentration of a solution that is formed by combining 600. mL of 0.10 M NaOH with 400. mL of 0.80 M HNO3at 25ºC?A) 0.080 MB) 0.010 MC) 0.80 MD) 0.45 ME) 0.26 M

Q: What is the pH of a solution that is formed at 25ºC by combining 300 mL of 0.040 M NaOH with 400 mL of 0.030 M HCl?A) 2.0B) 3.0C) 5.0D) 7.0E) 1.0

Q: What is the hydronium-ion concentration of a solution formed by combining 700. mL of 0.18 M HCl with 300. mL of 0.51 M NaOH at 25ºC?HCl(aq) + NaOH(aq)→NaCl(aq) + H2O(l)A) 0.13 MB) 3.7 x10-13MC) 0.33 MD) 0.18 ME) 0.027 M

Q: What is the hydronium-ion concentration of a solution formed by combining 400. mL of 0.21 M HNO3with 600. mL of 0.11 M NaOH at 25ºC?A) 0.082 MB) 6.7 x10-13MC) 0.21 MD) 0.018 ME) 0.11 M

Q: What molar ratio of acetic acid to sodium acetate is required to create a buffer solution having a pH of 4.89 at 25ºC? Kafor HC2H3O2 is 1.8x10-5.A) 0.72B) 1.4C) 0.56D) 2.0E) 2.9

Q: A certain weak base B has a base-ionization constant Kb of 2.4 x10-4at 25ºC. If strong acid is added to a solution of B, at what pH will [B] = [BH+]?A) 8.5B) 10.4C) 7.0D) 3.6E) 5.5

Q: What is the pH of a solution that is 0.026 M in HA and also 0.0060 M in NaA? (Ka=5.3x10-6)A) 8.15B) 4.64C) 5.91D) 5.28E) 7.70

Q: What is the hydronium-ion concentration in a solution resulting from mixing 173 mL of 0.100 M HCN and 73 mL of 0.100 M KOH at 25ºC? Ka for HCN = 4.9 x10-10 at 25ºC.A) 4.5 x10-6MB) 7.0 x10-6MC) 3.4 x10-13MD) 6.7 x10-10ME) 1.0 x10-13M

Q: What mass of sodium hydroxide must be added to 75.0 mL of 0.205 M acetic acid in order to create a buffer with a pH of 4.74? Ka for acetic acid is 1.8 x10-5.A) 40 gB) 0.31 gC) 1.0 gD) 0.000055 gE) 0.61 g

Q: What is the hydronium-ion concentration of a buffer solution that is 0.50 M Na2HPO4and 0.20 M NaH2PO4? For H3PO4, Ka1= 6.9 x10-3, Ka2= 6.2 x10-8, and Ka3= 4.8 x10-13.A) 1.7 x10-2MB) 2.8 x10-3MC) 1.6 x10-7MD) 2.5 x10-8ME) 1.9 x10-13M

Q: What is the pH of a buffer made by combining 175 mL of 0.33 M NaC2H3O2with 126 mL of 0.48 M HC2H3O2? The Ka of acetic acid is 1.75 x10-5.A) 4.74B) 4.78C) 5.79D) 4.69E) 5.24

Q: What is the hydrogen-ion concentration of a solution that is 0.052 M in acetic acid and 0.052 M in sodium acetate at 25ºC? The acid-ionization constant of acetic acid is 1.8 x10-5 at 25ºC.A) 1.8 x10-3MB) 1.8 x10-6MC) 1.8 x10-7MD) 1.8 x10-5ME) 1.8 x10-4M

Q: What is the pH of a solution that is 0.12 M in acetic acid, HC2H3O2, and 0.50 Min sodium acetate, NaC2H3O2, at 25ºC? Ka of acetic acid is 1.8 x10-5.A) 4.12B) 1.53C) 4.74D) 2.29E) 5.36

Q: Suppose a buffer solution is made from formic acid (HCHO2) and sodium formate (NaCHO2). What is the net ionic equation for the reaction that occurs when a small amount of sodium hydroxide is added to the buffer?A) NaOH(aq) + HCHO2(aq) → NaCHO2(aq) + H2O(l)B) Na+(aq) + HCHO2(aq) → NaH(aq) + HCO2+(aq)C) OH-(aq) + HCHO2(aq) → CHO2-(aq) + H2O(l)D) H3O+(aq) + OH-(aq) → 2H2O(l)E) NaOH(aq) + H3O+(aq) → Na+(aq) + 2H2O(l)

Q: Suppose a buffer solution is made from formic acid (HCHO2) and sodium formate (NaCHO2). What is the net ionic equation for the reaction that occurs when a small amount of hydrochloric acid is added to the buffer?A) H3O+(aq) + HCHO2(aq) → H2O(l) + H2CHO2+(aq)B) H3O+(aq) + CHO2-(aq) → HCHO2(aq) + H2O(l)C) HCl(aq) + CHO2-(aq) → HCHO2(aq) + Cl-(aq)D) HCl(aq) + OH-(aq) → H2O(l) + Cl"(aq)E) H3O+(aq) + OH-(aq) →2H2O(l)

Q: A weak acid, HF, is in solution with dissolved sodium fluoride, NaF. If HCl is added, which ion will react with the extra hydrogen ions from the HCl to keep the pH from changing? A) Na+ B) OH" C) Na" D) F" E) none of these

Q: Which of the following mixtures will be a buffer when dissolved in a liter of water? A) 0.4 mol NH3and 0.4 mol HCl B) 0.3 mol NaCl and 0.3 mol HCl C) 0.1 mol Ca(OH)2and 0.3 mol HI D) 0.2 mol H3PO4and 0.1 mol NaOH E) 0.2 mol HBr and 0.1 mol NaOH

Q: Which of the following solutions would show the greatest change in pH upon the addition of 10.0 mL of 1.0 M NaOH to 1.0 L of the solution?A) 0.50 M HC2H3O2B) 0.50 M HC2H3O2+ 0.50 M NaC2H3O2C) 0.10 M HC2H3O2+ 0.10 M NaC2H3O2D) 0.10 M HC2H3O2E) 0.50 M NaC2H3O2

Q: Which of the following mixtures will be a buffer when dissolved in 1 L of water?A) 0.3 mol KCl and 0.3 mol HClB) 0.2 mol HC2H3O2 and 0.1 mol NaOHC) 0.4 mol NH3 and 0.4 mol HClD) 0.2 mol HBr and 0.1 mol NaOHE) 0.1 mol Ba(OH)2 and 0.2 mol HCl

Q: Which of the following solutions will not yield an effective NaH2PO4/Na2HPO4 buffer?A) 2.0 M NaH2PO4+ 1.0 M NaOHB) 1.0 M NaH2PO4+ 1.0 M Na2HPO4C) 1.0 M H3PO4+ 1.0 M Na3PO4D) 2.0 M Na2HPO4+ 1.0 M HClE) 1.0 M H3PO4+ 1.0 M NaH2PO4

Q: Which of the following will give a buffer with a pH near 4.76 when the acid and conjugate base are mixed in equimolar proportions?Acid KaNH4+(from ammonia)5.69 x10-10HC2H3O2(acetic acid) 1.75 x10-5HF (hydrofluoric acid) 6.8 x10-4CH3CH2NH3+(from ethylamine)2.12 x10-11A) acetic acidB) hydrofluoric acidC) ethylamineD) noneE) ammonia

Q: Which of the following is the most effective buffer system for a pH value of 4.45?A) H2CO3/HCO3- (Ka1 for H2CO3 is 4.3 x10-7)B) HCO3-/CO32- (Ka2 for H2CO3 is 4.8 x10-11)C) H2S/HS- (Ka1 for H2S is 8.9 x10-8)D) HC2O4-/C2O42- (Ka2 for H2C2O4 is 5.1 x10-5)E) H3PO4/H2PO4- (Ka1 for H3PO4 is 6.9 x10-3)

Q: Which of the following would be the best mole ratio of conjugate acid to conjugate base for a large buffer capacity?A) 100:1B) 1:1C) 1:100D) 1:10E) 10:1

Q: Which of the following combinations is not suitable for making a buffer?A) HClO4 and NaClO4B) NaH2PO4 and Na2HPO4C) NH4Cl and NH3D) H3PO4 and NaH2PO4E) Na2CO3 and NaHCO3

Q: Calculate the pH of a solution that is 2.00 MHF, 1.00 M NaOH, and 0.690 M NaF. (Ka=6.8x10-4)A) 3.40B) 2.94C) 3.17D) 2.71E) none of these

Q: What is the equilibrium fluoride ion concentration of a solution that initially consists of 0.47 M HF and 0.418 M HCl? Ka for HF is 6.8x10-4.A) MB) MC) MD) ME) M

Q: What is the pH of the solution if 0.021 g of sodium fluoride is added to 130.0 mL of a 0.098M HF solution? Ka for HF is 6.8x10-4.A) 2.21B) 5.08C) 2.88D) 2.11E) 4.85

Q: For a solution equimolar in HCN and NaCN, which statement is false? A) [H+] is equal to Ka. B) [H+] is larger than it would be if only the HCN were in solution. C) Addition of NaOH will increase [CN"] and decrease [HCN]. D) Addition of more NaCN will shift the acid-dissociation equilibrium of HCN to the left. E) Addition of more HCN will shift the acid-dissociation equilibrium of HCN to the right.

Q: When equal volumes of solutions are mixed, as shown below, what will be the relative pH values of the resulting solutions? A) I < V < III < II < IV B) V < I < IV < II < III C) III < I < IV = V < II D) I = V < III < II < IV E) III < I = V < III < IV < II

Q: _15.0 mL of 0.50 M HCl is added to a 100.0-mL sample of 0.377 M HNO2(Kafor HNO2=4.0x10-4). What is the equilibrium concentration of NO2"ions?A) 3.3 x10-1 MB) 1.3 x10-4 MC) 4.5 x10-2 MD) 2.0 x10-3 ME) none of these

Q: What will happen if a small amount of sodium hydroxide is added to a 0.1 M solution of ammonia?A) Kb for ammonia will decrease.B) The percent ionization of ammonia will increase.C) Kb for ammonia will increase.D) The percent ionization of ammonia will decrease.E) The percent ionization of ammonia will remain unchanged.

Q: What will happen if a small amount of hydrochloric acid is added to a 0.1 M solution of HF?A) The percent ionization of HF will decrease.B) Ka for HF will increase.C) Ka for HF will decrease.D) The percent ionization of HF will remain unchanged.E) The percent ionization of HF will increase.

Q: Which of the following substances, if added to a 0.10 M HC2H3O2solution, would not increase the hydronium-ion concentration?A) Na2CO3(s)B) NaHSO4(s)C) H2C2O4(s)D) HF(l)E) HCl(g)

Q: What is the hydroxide-ion concentration of a 0.250 M sodium oxalate (Na2C2O4) solution? For oxalic acid (H2C2O4), Ka1= 5.6 x10-2and Ka2= 5.1 x10-5.A) 7.0 x10-6MB) 1.0 x10-7MC) 9.4 x10-2MD) 3.5 x10-3ME) 2.1 x10-7M

Q: What is the pOH of a solution prepared by adding 1.42 g of sodium nitrite to 125 mL of water? Ka of HNO2 is 4.5 x10-4.A) 11.92B) 2.08C) 8.28D) 7.00E) 5.72

Q: What is the pH of a solution prepared by adding 1.67 g of potassium nitrite to 185 mL of water? Ka of HNO2is 4.5 x10-4.A) 5.82B) 2.18C) 7.00D) 11.82E) 8.18

Q: What is the pOH of a solution prepared by adding 1.12 g of ammonium iodide to 105 mL of water? Kb of NH3 is 1.8 x10-5.A) 2.94B) 11.06C) 7.00D) 5.19E) 8.81

Q: What is the pH of a solution prepared by adding 0.490 g of ammonium iodide to 155 mL of water? Kb of NH3 is 1.8 x10-5.A) 5.46B) 3.21C) 7.00D) 8.54E) 10.79

Q: In a 0.10 M solution of sodium hydrogen sulfate, the HSO4-ion is 29% dissociated. What is Ka2 for H2SO4?A) 2.4 x10-1B) 1.2 x10-2C) 1.0 x10-2D) 8.4 x10-3E) 2.0 x10-2

Q: What is the hydroxide-ion concentration in a 0.22 M solution of Na2CO3? For carbonic acid, Ka1=4.2x10-7 and Ka2=4.8x10-11. (Kw=1.0x10-14)A) 6.8 x10-3MB) 2.0 x10-4MC) 7.2 x10-5MD) 4.2 x10-9ME) 3.2 x10-6M

Q: What is the pH of a 0.38 Msolution of sodium propionate, NaC3H5O2, at 25ºC? (For propionic acid, HC3H5O2, Ka= 1.3 x10-5 at 25ºC.)A) 6.11B) 4.77C) 11.10D) 7.89E) 9.23

Q: What is Kcfor the following equilibrium? For phosphoric acid (H3PO4), Ka1=6.9x10-3, Ka2=6.2x10-8, and Ka3=4.8x10-13.HPO42-(aq) + OH-(aq) PO43-(aq) + H2O(l)A) 7.3 x10-16B) 6.4 x10-23C) 491D) 48E) 2.3 x10-35

Q: The two acid-ionization constants for sulfurous acid, H2SO3, are 1.3 x10-2 and 6.3 x10-8at 25ºC. What is Kb for the HSO3-ion?A) 6.3 x10-8.B) 6.2 x10-22.C) 7.7 x10-13.D) 1.3 x10-2.E) 8.2 x10-10.

Q: What is Kafor the methylammonium cation, CH3NH3+, at 25C? (Kbfor CH3NH2=4.4x10-4at 25ºC.)A) 1.0 x10-7B) 4.4 x1010C) 4.4 x10-18D) 2.3 x10-11E) 4.4 x10-4

Q: What is Kb for the following equilibrium? Ka for HNO2is 5.0 x10-4.NO2-(aq) + H2O(l) HNO2(aq) + OH-(aq)A) 2.0 x10-4B) 5.0 x10-4C) 5.0 x1010D) 5.0 x1018E) 2.0 x10-11

Q: The Ka for hydrofluoric acid is 6.8 x10-4. What is Kb for the fluoride ion?A) 1.5 x10-11B) 6.8 x10-4C) 1.5 x103D) 6.8 x1010E) 6.8 x10-18

Q: What is Ka at 25ºC for the following equilibrium?C6H5NH3+(aq) + H2O(l) C6H5NH2(aq) + H3O+(aq)Kb(C6H5NH2) = 4.2 x10-10at 25ºC.A) 4.2 x10"4B) 2.4 x103C) 4.2 x10-10D) 4.2 x104E) 2.4 x10-5

Q: Consider the reaction NH3(aq) + H2O(l) NH4+(aq) + OH"(aq). Kb for NH3 is 1.8x10-5 at 25ºC. What is Ka for the NH4+ion at 25ºC?A) 5.6 x104B) 5.6 x10-10C) 1.8 x10-5D) 7.2 x10-12E) 9.2 x10-8

Q: Which of the following salts forms an acidic aqueous solution? A) NaNO2 B) KCH3CO2 C) Rb2O D) FeCl3 E) NaCN

Q: Which of the following salts will produce a neutral solution when added to pure water? A) LiHCO3 B) NH4NO3 C) Na2SO4 D) RbNO2 E) KNO3

Q: Which of the following salts is most likely to form an aqueous solution having the pH shown in the figure below? A) KCl B) Zn(NO3)2 C) NaCN D) NH4Cl E) LiBr

Q: Which of the following salts is most likely to form an aqueous solution having the pH shown in the figure below? A) NH4Cl B) NaBr C) K2CO3 D) RbCN E) LiNO3

Q: Which of the following salts is most likely to form an aqueous solution having the pH shown in the figure below? A) Na2CO3 B) RbF C) NH4Cl D) Zn(NO3)2 E) KCl

Q: Which of the following salts will produce an acidic solution when added to pure water? A) Cs2CO3 B) NaF C) KCN D) Al(NO3)3 E) Li2S

Q: Which sodium salt(s) of an amphiprotic ion will produce an acidic solution when added to pure water? 1) NaHSO4(Ka= 1.03 x10-2; Kb= 9.71 x10-13) 2) NaHCO3(Ka= 4.69 x10-11; Kb= 2.24 x10-8) 3) NaHSO3(Ka= 6.73 x10-8; Kb= 7.19 x10-13) A) 1 only B) 2 only C) 3 only D) 1 and 3 E) 1 and 2

Q: The amphiprotic anion monohydrogenphosphate acts as both an acid and a base in aqueous solution. Given the following acid-ionization and base-hydrolysis constants, what will be the approximate equilibrium pH of an aqueous solution of sodium monohydrogenphosphate? Ka= Kb= A) basic B) acidic C) neutral

Q: Given the following, what will be the approximate equilibrium pH of an aqueous solution of ammonium cyanide, NH4CN?NH4+ Ka= 5.69 x10-10HCN Ka= 6.2 x10-10A) slightly basicB) slightly acidicC) nearly neutral

Q: Given the following, what will be the approximate equilibrium pH of an aqueous solution of ammonium acetate, NH4CH3CO2?NH4+ Ka= 5.69 x10-10CH3CO2- Kb= 5.71 x10-10A) very basicB) very acidicC) nearly neutral

Q: Which of the following solutions has the highest hydroxide-ion concentration?A) 0.10 M NH4ClO4B) 0.10 M NaIC) 0.10 M NaNO3D) 0.10 M NH4ClE) 0.10 M NaCN

Q: Which of the following statements is true concerning a 0.1 M solution of Na2S and a 0.1M solution of NaHS? For H2S, Ka1=1.0x10-7 and Ka2=1.3x10-13.A) Both solutions are neutral.B) The sodium hydrogen sulfide solution is the more basic.C) Both solutions have the same pH.D) The sodium sulfide solution is the more basic.E) Both the solutions are acidic.

Q: Which of the following equilibria best represents the hydrolysis reaction that occurs in an aqueous solution of KNO2?A) NO2-(aq)+ H2O(l) HNO3(aq) + 2H+(aq)B) NO2-(aq) + H2O(l) HNO2(aq) + OH-(aq)C) NO2-(aq)+ H3O+(aq) HNO2(aq) + H2O(l)D) K+(aq) + NO2-(aq) + H2O(l) KOH(aq) + HNO2(aq)E) K+(aq) + H2O(l) KOH(aq) + H+(aq)

Q: Which of the following equilibria best represents the hydrolysis reaction that occurs in an aqueous solution of NH4Cl?A) Cl-(aq)+ H3O+(aq) HCl(aq) + H2O(l)B) NH4+(aq)+ H2O(l) NH3(aq) + H3O+(aq)C) NH4+(aq) + OH-(aq) NH3(aq) + H2O(l)D) Cl-(aq) + H2O(l) HCl(aq) + OH-(aq)E) NH4+(aq) + Cl-(aq) NH4Cl(s)

Q: Saccharin is a weak organic base with a Kb of 4.80 x10-3. A 0.297-g sample of saccharin dissolved in 25.0 mL of water has a pH of 12.190. What is the molar mass of saccharin?A) 0.616 g/molB) 19.3 g/molC) 184 g/molD) 181 g/molE) 119 g/mol

Q: A 0.0884 M solution of a weak base has a pH of 11.79. What is the identity of the weak base? Weak Base Kb Ethylamine (CH3CH2NH2) 4.7 x10-4 Hydrazine (N2H4) 1.7 x10-6 Hydroxylamine (NH2OH) 1.1 x10-8 Pyridine (C5H5N) 1.4 x10-9 Aniline (C6H5NH2) 4.2 x10-10 A) hydrazineB) pyridineC) anilineD) ethylamineE) hydroxylamine

Q: A solution of aniline (C6H5NH2, Kb= 4.2 x10-10) has a pH of 8.75 at 25oC. What was the initial concentration of aniline?A) 1.8 x10-9MB) 9.3 x10-9MC) 7.7 x10-2MD) 4.2 x10-10ME) 5.6 x10-6M

Q: What is the equilibrium concentration of ammonium ion in a 0.51 M solution of ammonia (NH3, Kb= 1.8 x10-5) at 25oC?A) 2.0 x10-14MB) 3.3 x10-12MC) 3.0 x10-3MD) 6.0 x10-3ME) 5.1 x10-1M

Q: What is the percent ionization at equilibrium in a 0.75 M solution of dimethylamine, (CH3)2NH (Kb= 5.1 x10-4), at 25oC?A) 2.6%B) 0.068%C) 1.9%D) 100%E) 75%

Q: What is the hydroxide-ion concentration at equilibrium in a 0.17 M solution of ethylamine (C2H5NH2, Kb= 4.7 x10-4) at 25oC?A) 8.7 x10-3MB) 5.4 x10-2MC) 5.9 x10-14MD) 1.1 x10-12ME) 1.7 x10-1M

Q: What is the hydronium-ion concentration at equilibrium in a 0.72 Msolution of aniline (C6H5NH2, Kb= 4.2 x10-10) at 25oC?A) 1.4 x10-14MB) 7.2 x10-1MC) 5.8 x10-10MD) 1.7 x10-5ME) 2.4 x10-5M

Q: What is the pH of a 0.24 Msolution of methylamine (CH3NH2, Kb= 4.4 x10-4) at 25oC?A) 5.63B) 0.62C) 12.00D) 13.38E) 2.00

Q: What is the pOH of a 0.20 Msolution of pyridine (Kb= 1.4 x10-9) at 25ºC?A) 1.40B) 4.08C) 8.85D) 4.78E) 11.00

Q: What is the base-ionization equilibrium constant for an aqueous solution of ammonia, NH3?A) B) C) D) E) none of these

Q: Which of the following reactions is associated with the definition of Kb?A) CN-(aq) + H+(aq) HCN(aq)B) F-(aq) + H2O(l) HF(aq) + OH-(aq)C) Zn(OH2)62+(aq) [Zn(OH2)5OH]+(aq) + H+(aq)D) Cr3+(aq) + 6H2O(l) Cr(OH2)63+(aq)E) none of these

Q: For which of the following equilibria does Kccorrespond to the base-ionization constant, Kb,of HCO3-?A) HCO3-(aq) + H2O(l) CO32-(aq) + H3O+(aq)B) HCO3-(aq) + H2O(l) H2CO3(aq) + OH-(aq)C) H2CO3(aq) + H2O(l) HCO3-(aq) + H3O+(aq)D) HCO3-(aq) + OH-(aq) CO32-(aq) + H2O(l)E) HCO3-(aq) + H3O+(aq) H2CO3(aq) + H2O(l)