Q&A Hero

Q: Arrange the following 0.10 M aqueous solutions in order of increasing pH: NaOH, HBr, NaCH3CO2, KBr, NH4Br. A) HBr, KBr, NH4Br, NaCH3CO2, NaOH B) NaOH, NaCH3CO2, NH4Br, KBr, HBr C) NaOH, NaCH3CO2, KBr, NH4Br, HBr D) HBr, NH4Br, KBr, NaCH3CO2, NaOH

Q: If an equal number of moles of the weak acid HCN and the strong base KOH are added to water, is the resulting solution acidic, basic, or neutral? A) acidic B) basic C) neutral D) There is insufficient information provided to answer this question.

Q: Which one of the following salts, when dissolved in water, produces the solution with the highestpH? A) NaHSO4 B) LiClO4 C) MgO D) CH3NH3I

Q: Which of the following salts are acidic? A) LiCl, NaCl, KCl B) NH4Cl, CuCl2, AlCl3 C) NaCH3CO2, KCH3CO2, RbCH3CO2 D) NaCl, NH4Cl, Na2CO3

Q: Dihydrogen phosphate H2PO4-, has an acid dissociation constant of 6.2 10-7. What is the conjugate base of H2PO4-and what is its base dissociation constant? A) H3PO4, 1.6 106 B) H3PO4, 1.6 10-8 C) HPO42-, 1.6 106 D) HPO42-, 1.6 10-8

Q: Acetic acid CH3COOH, has an acid dissociation constant of 1.8 10-5. What is the conjugate base of acetic acid and what is its base dissociation constant? A) CH3C(OH)2+, 5.6 104 B) CH3C(OH)2+, 5.6 10-10 C) CH3COOH, 5.6 10-10 D) CH3CO2-, 5.6 10-10

Q: Methylamine CH3NH2, has a base dissociation constant of 3.7 10-4. What is the conjugate acid of methylamine and what is its acid dissociation constant? A) CH3NH3+, 2.7 103 B) CH3NH3+, 3.7 10-4 C) CH3NH3+, 2.7 10-11 D) CH3NH2-, 2.7 10-11

Q: Ammonia NH3, has a base dissociation constant of 1.8 10-5. What is the conjugate acid of ammonia and what is its acid dissociation constant? A) NH4+, 1.9 109 B) NH4+, 1.8 10-5 C) NH4+, 5.6 10-10 D) NH2-, 5.6 10-10

Q: What is the relationship between Kaand Kbat 25C for a conjugate acid base pair? A) Ka Kb= 1 10-14 B) Ka/Kb= 1 10-14 C) Kb/Ka= 1 10-14 D) Ka+ Kb= 1 10-14

Q: How many grams of pyridine are there in 100 mL of an aqueous solution that has a pH of 9.00? The Kbfor pyridine is 1.9 10-9and the equation of interest isC5H5N(aq) + H2O(l) C5H5NH+(aq) + OH-(aq).A) 0.053 gB) 0.42 gC) 0.79 gD) 7.9 g

Q: Determine the ammonia concentration of an aqueous solution that has a pH of 11.50. The equation for the dissociation of NH3(Kb= 1.8 10-5) isNH3(aq) + H2O(l) NH4+(aq) + OH-(aq).A) 2.5 MB) 0.55 MC) 5.7 10-3MD) 3.2 10-3M

Q: Aniline, (C6H5NH2, Kb= 4.3 10-10at 25C) is an industrially important amine used in the making of dyes. Determine the pH of an aniline solution made by dissolving 3.90 g of aniline in enough water to make 100 mL of solution. A) 4.87 B) 9.13 C) 9.74 D) 10.74

Q: What is the pH of a 0.30 M pyridine solution that has a Kb= 1.9 10-9? The equation for the dissociation of pyridine isC5H5N(aq) + H2O(l) C5H5NH+(aq) + OH-(aq).A) 4.62B) 8.72C) 9.38D) 10.38

Q: What is the pH of a 0.100 M NH3solution that has Kb= 1.8 10-5? The equation for the dissociation of NH3isNH3(aq) + H2O(l) NH4+(aq) + OH-(aq).A) 1.87B) 2.87C) 11.13D) 12.13

Q: Which of the following can be classified as a weak base? A) CH3NH2 B) NH2OH C) Both CH3NH2and NH2OH D) Neither CH3NH2nor NH2OH

Q: What is the selenide ion concentration [Se2-] for a 0. 100 M H2Se solution that has the stepwise dissociation constants ofKa1= 1.3 10-4andKa2= 1.0 10-11? A) 3.6 10-3M B) 1.3 10-4M C) 1.3 10-5M D) 1.0 10-11M

Q: What is the pH of a 0.10 M H2Se solution that has the stepwise dissociation constants Ka1= 1.3 10-4and Ka2= 1.0 10-11? A) 2.44 B) 3.89 C) 4.89 D) 5.50

Q: Calculate the concentration of bicarbonate ion, HCO3-, in a 0.0 10 M H2CO3solution that has the stepwise dissociation constants Ka1= 4.3 10-7and Ka2= 5.6 10-11. A) 6.6 10- 5M B) 4.3 10-7M C) 4.3 10- 9M D) 5.6 10-11M

Q: Calculate the pH of a 0.20 M H2SO3solution that has the stepwise dissociation constants Ka1= 1.5 10-2and Ka2= 6.3 10-8. A) 1.26 B) 1.32 C) 1.82 D) 2.52

Q: Calculate the pH of a 0.020 M carbonic acid solution, H2CO3(aq), that has the stepwise dissociation constantsKa1= 4.3 10-7and Ka2= 5.6 10-11. A) 1.70 B) 4.03 C) 6.37 D) 10.25

Q: What is the second stepwise equilibrium constant expression for phosphoric acid H3PO4? A) Ka2= ([H3O+][H2PO4-])/([H3PO4]) B) Ka2= ([H3O+]2[HPO42-])/([H3PO4]) C) Ka2= ([H3O+]3[PO43-])/([H3PO4]) D) Ka2= ([H3O+][HPO42-])/([H2PO4-])

Q: Which of the following are weak diprotic acids? A) carbonic acid - H2CO3, hydrosulfuric acid - H2S, acetic acid - CH3CO2H B) formic acid - HCO2H, acetic acid - CH3CO2H, benzoic acid - C6H5CO2H C) carbonic acid - H2CO3, oxalic acid - H2C2O4, sulfurous acid - H2SO3 D) hydrocyanic acid - HCN, sulfuric acid - H2SO4, phosphoric acid - H3PO4

Q: The percent dissociation of acetic acid changes as the concentration of the acid decreases. A 100-fold decrease in acetic acid concentration results in a ________ fold ________ in the percent dissociation. A) 10, increase B) 10, decrease C) 100, increase D) 100, decrease

Q: What is the percent dissociation of a benzoic acid solution with pH = 2.59? The acid dissociation constant for this monoprotic acid is 6.5 10"5. A) 0.50% B) 1.5% C) 2.5% D) 3.5%

Q: Vinegar is a 5.0% solution by weight of acetic acid (CH3CO2H) in water. Given that the pH for acetic acid is 2.41, the Ka= 1.8 10-5 and assuming the density of vinegar to be 1.00 g/cm3, what is the percent dissociation of acetic acid in vinegar?A) 0.47%B) 1.5%C) 4.0%D) 5.0%

Q: Vinegar is a 5.0% solution by weight of acetic acid (CH3CO2H) in water. Given thatKa= 1.8 10-5 for acetic acid and assuming the density of vinegar to be 1.00 g/cm3, what is the pH of this vinegar solution?A) 2.00B) 2.41C) 2.87D) 4.74

Q: Potassium hydrogen phthalate (molar mass = 204.2 g/mol) is one of the most commonly used acids for standardizing solutions containing bases. KHP is a monoprotic weak acid with Ka= 3.91 10-6. Calculate the pH of the solution that results when 0.40 g of KHP is dissolved in enough water to produce 25.0 mL of solution.A) 2.10B) 3.26C) 4.30D) 5.41

Q: Benzoic acid (C6H5CO2H = HBz) solutions are sometimes used in experiments to determine the molarity of a basic solution of unknown concentration. What is the pH of a 0.100 M solution of benzoic acid if Ka= 6.5 10-5and the equilibrium equation of interest isHBz(aq) + H2O(l) H3O++ Bz-(aq)?A) 1.00B) 2.59C) 4.19D) 5.19

Q: A tablet containing 500.0 mg of aspirin (acetylsalicylic acid or HC9H7O4) was dissolved in enough water to make 100 mL of solution. Given that Ka= 3.0 10-4for aspirin, what is the pH of the solution?A) 1.57B) 2.54C) 3.52D) 5.08

Q: Para-Aminobenzoic acid (PABA), p-H2NC6H4(COOH), is used in some sunscreens and hair conditioning products. Calculate the pH of an aqueous solution with [PABA] = 0.030 M and Ka= 2.2 10-5. A) 1.52 B) 3.09 C) 4.66 D) 6.18

Q: What is the hydronium ion concentration of a 0.100 M hypochlorous acid solution withKa= 3.5 10-8? The equation for the dissociation of hypochlorous acid is:HOCl(aq) + H2O(l) H3O+(aq) + OCl-(aq).A) 1.9 10-4B) 5.9 10-4C) 1.9 10-5D) 5.9 10-5

Q: What is the hydronium ion concentration of a 0.100 M acetic acid solution with a Ka= 1.8 10-5? The equation for the dissociation of acetic acid is:CH3CO2H(aq) + H2O(l) H3O+(aq) + CH3CO2-(aq).A) 1.3 10-2MB) 4.2 10-2MC) 1.3 10-3MD) 4.2 10-3M

Q: What is the strongest monoprotic acid of the following set if all the acids are at 0.100 M concentration? A) hydrofluoric acid with Ka= 3.5 10-4 B) benzoic acid with Ka= 6.5 10-5 C) acetic acid with Ka= 1.8 10-5 D) hypochlorous acid with Ka= 3.5 10-8

Q: The pH of 0.150 M CH3CO2H, acetic acid, is 2.78. What is the value of Kafor acetic acid? A) 2.8 10-6 B) 1.9 10-5 C) 1.7 10-3 D) 1.1 10-2

Q: The pH of 0.255 M HCN is 4.95. What is the value of Kafor hydrocyanic acid? A) 1.3 10-10 B) 4.9 10-10 C) 1.1 10-5 D) 4.4 10-5

Q: Determine the acid dissociation constant for a 0.020 M formic acid solution that has a pH of 2.74. Formic acid is a weak monoprotic acid and the equilibrium equation of interest isHCOOH(aq) + H2O(l) H3O+(aq) + HCO2-(aq).A) 1.8 10-3B) 1.8 10-4C) 3.6 10-4D) 3.6 10-5

Q: Determine the acid dissociation constant for a 0.010 M nitrous acid solution that has a pH of 2.70. Nitrous acid is a weak monoprotic acid and the equilibrium equation of interest isHNO2(aq) + H2O(l) H3O+(aq) + NO2-(aq).A) 8.0 10-3B) 2.0 10-3C) 5.0 10-4D) 4.0 10-4

Q: Determine the acid dissociation constant for a 0.10 M acetic acid solution that has a pH of 2.87. Acetic acid is a weak monoprotic acid and the equilibrium equation of interest isCH3COOH(aq) + H2O(l) H3O+(aq) + CH3CO23-(aq)A) 1.3 10-2B) 1.3 10-3C) 1.8 10-5D) 1.8 10-6

Q: What is the equilibrium constant expression (Ka) for the acid dissociation of nitrous acid HNO2? The equation of interest is HNO2(aq) + H2O(l) ⇌H3O+(aq) + NO2-(aq). A) Ka= ([H3O+][NO2-])/([HNO2][H2O]) B) Ka= ([H3O+][NO2-])/([HNO2]) C) Ka= ([HNO2][H2O])/([H3O+][NO2-]) D) Ka= ([HNO2])/([H3O+][NO2-])

Q: What is the equilibrium constant expression (Ka) for the acid dissociation of hydrocyanic acid HCN? The equation of interest isHCN(aq) + H2O(l) H3O+(aq) + CN-(aq).A) Ka= ([H3O+][CN-])/([HCN][H2O])B) Ka= ([H3O+][CN-])/([HCN])C) Ka= ([HCN][H2O])/([H3O+][CN-])D) Ka= ([HCN])/([H3O+][CN-])

Q: What is the pH of a solution prepared by mixing 100.00 mL of 0.020 M Ca(OH)2with 50.00 mL of 0.100 M NaOH? Assume that the volumes are additive. A) 12.67 B) 12.78 C) 12.95 D) 13.25

Q: What is the pH of a solution made by mixing 100.0 mL of 0.10 M HNO3, 50.0 mL of 0.20 M HCl, and 100.0 mL of water? Assume that the volumes are additive. A) 0.30 B) 0.82 C) 1.00 D) 1.10

Q: What is the pH of a solution made by mixing 100.00 mL of 0.20 M HCl with 50.00 mL of 0.10 M HCl? Assume that the volumes are additive. A) 0.15 B) 0.52 C) 0.78 D) 1.70

Q: What is the pH of a solution prepared by diluting 25.00 mL of 0.020 M Ba(OH)2with enough water to produce a total volume of 250.00 mL? A) 2.40 B) 2.70 C) 11.30 D) 11.60

Q: What is the pH of a solution prepared by diluting 25.00 mL of 0.10 M HCl with enough water to produce a total volume of 100.00 mL? A) 1.00 B) 1.60 C) 2.00 D) 3.20

Q: What is the pH of a solution prepared by dissolving 0.15 gram of solid CaO (lime) in enough water to make 2.00 L of aqueous Ca(OH)2(limewater)?CaO(s) + H2O(l) -> Ca2+(aq) + 2 OH-(aq)A) 2.57B) 2.87C) 11.13D) 11.43

Q: What is the pH of a 0.020 M Ba(OH)2solution? A) 1.40 B) 1.70 C) 12.30 D) 12.60

Q: What is the pH of a 0.020 M RbOH solution? A) 0.020 B) 0.040 C) 1.70 D) 12.30

Q: What is the pH of a 0. 020 M HClO4solution? A) 0. 020 B) 0. 040 C) 1.70 D) 12.30

Q: What is the approximate pH of a solution X that gives the following responses with the indicators shown? Indicators HIn  In- pH range Solution X methyl orange red-yellow 3.2-4.4 yellow methyl red red-yellow 4.8-6.0 yellow bromothymol blue yellow-blue 6.0-7.6 blue phenolphthalein colorless-pink 8.2-10.0 pink A) 4.8 - 6.0 B) 6.0 - 7.6 C) 7.6 - 8.2 D) > 8.2

Q: What is the approximate pH of a solution X that gives the following responses with the indicators shown? Indicators HIn  In- pH range Solution X methyl orange red-yellow 3.2-4.4 yellow methyl red red-yellow 4.8-6.0 orange bromothymol blue yellow-blue 6.0-7.6 yellow phenolphthalein colorless-pink 8.2-10.0 colorless A) 3.2 - 4.4 B) 4.8 - 6.0 C) 6.0 - 7.6 D) 8.2 - 10.0

Q: What is the approximate pH of a solution X that gives the following responses with the indicators shown? Indicators HIn  In- pH range Solution X methyl orange red-yellow 3.2-4.4 yellow methyl red red-yellow 4.8-6.0 yellow bromothymol blue yellow-blue 6.0-7.6 green phenolphthalein colorless-pink 8.2-10.0 colorless A) 3.2 - 4.4 B) 4.8 - 6.0 C) 6.0 - 7.6 D) 8.2 - 10.0

Q: At 25C, the pH of a vinegar solution is 2.60. What are the values of [H3O+] and [OH-] in the solution? A) 3.99 10-12M, 2.51 10-3M B) 2.51 10-3M, 3.98 10-12M C) 2.51 10-3M, 11.40 M D) 2.60 M, 11.40 M

Q: What statement is most consistent for an acid with a pH = 3? A) one one-hundredth as strong as an acid with a pH of 5 B) half a strong as an acid with a pH = 5 C) twice as strong as an acid with a pH of 5 D) one hundred times as strong as an acid with a pH = 5

Q: What is the hydroxide ion concentration of a lye solution that has a pH of 11.20? A) 6.31 10-12M B) 1.58 10-3M C) 2.80 M D) 11.20 M

Q: What is the hydronium ion concentration of an acid rain sample that has a pH of 3.15? A) 1.41 10-11M B) 7.08 10-4M C) 3.15 M D) 10.85 M

Q: What is the hydronium ion concentration and the pH for an aqueous solution of NH3that has a hydroxide ion concentration of 2.25 10-3M? A) 4.44 10-11M, 3.65 B) 4.44 10-11M, 10.35 C) 4.44 10-12M, 2.65 D) 4.44 10-12M, 11.35

Q: What is the hydroxide ion concentration and the pH for a hydrochloric acid solution that has a hydronium ion concentration of 1.50 10-4M? A) 6.67 10-10M, 4.82 B) 6.67 10-10M, 9.18 C) 6.67 10-11M, 3.82 D) 6.67 10-11M, 10.18

Q: Calculate the pH for an aqueous solution of pyridine that contains 2.15 10-4M hydroxide ion. A) 4.65 10-11 B) 2.15 10-4 C) 3. 67 D) 10. 33

Q: Calculate the pH for an aqueous solution of acetic acid that contains 2.15 10-3M hydronium ion. A) 4.65 10-12 B) 2.15 10-3 C) 2.67 D) 11.33

Q: If the ionization constant of water, Kw, at 40C is 2.92 10-14, then what is the hydronium ion concentration and pH for an acidic solution? A) [H3O+] > 1.71 10-7M and pH > 6.77 B) [H3O+] > 1.71 10-7M and pH < 6.77 C) [H3O+] < 1.71 10-7M and pH > 6.77 D) [H3O+] < 1.71 10-7M and pH < 6.77

Q: An acidic solution at 25C will have a hydronium ion concentration ________ and a pH value ________. A) [H3O+] > 1 10-7M, pH > 7.00 B) [H3O+] > 1 10-7M, pH < 7.00 C) [H3O+] < 1 10-7M, pH > 7.00 D) [H3O+] < 1 10-7M, pH < 7.00

Q: Human tears have a concentration of H3O+that is 3.16 10-8. The concentration of OH-in human tears is A) greater than 3.16 10-7and tears are acidic. B) greater than 3.16 10-7and tears are basic. C) less than 3.16 10-7and tears are acidic. D) less than 3.16 10-7and tears are basic.

Q: Normal rainfall has a concentration of OH-that is 3.98 10-9. The concentration of H3O+in normal rainfall is A) greater than 3.98 10-9, and the rain is acidic. B) greater than 3.98 10-9, and the rain is basic. C) less than 3.98 10-9, and the rain is acidic. D) less than 3.98 10-9, and the rain is basic.

Q: If the ionization constant of water, Kw, at 40C is 2.92 10-14, then what is the hydronium ion concentration for a neutral solution? A) [H3O+] < 1.00 10-7M B) [H3O+] > 1.71 10-7M C) [H3O+] = 1.71 10-7M D) [H3O+] < 1.71 10-7M

Q: A solution with a hydroxide ion concentration of 4.15 10-4M is ________ and has a hydrogen ion concentration of ________. A) acidic, 2.41 10-10M B) acidic, 2.41 10-11M C) basic, 2.41 10-10M D) basic, 2.41 10-11M

Q: A solution with a hydrogen ion concentration of 3.25 10-2M is ________ and has a hydroxide concentration of ________. A) acidic, 3.08 10-12M B) acidic, 3.08 10-13M C) basic, 3.08 10-12M D) basic, 3.08 10-13M

Q: Calculate the hydroxide ion concentration in an aqueous solution that contains 3.50 10-3M in hydronium ion. A) 2.86 10-4M B) 2.86 10-11M C) 2.86 10-12M D) 3.50 10-12M

Q: Calculate the hydronium ion concentration in an aqueous solution that contains 2.50 10-4M in hydroxide ion. A) 4.00 10-9M B) 4.00 10-10M C) 4.00 10-11M D) 5.00 10-11M

Q: At 50C the value of Kwis 5.5 10-14. A basic solution at 50C has A) [H3O+] < [OH-] < 2 10-7M. B) [H3O+] < 2 10-7M < [OH-]. C) [H3O+] = [OH-] < 2 10-7M. D) [H3O+] > 2 10-7M < [OH-].

Q: An acidic solution at 25C has A) [H3O+] > [OH-] > 1 10-7M. B) [H3O+] > 1 10-7M > [OH-]. C) [H3O+] = [OH-] > 1 10-7M. D) [H3O+] < 1 10-7M > [OH-].

Q: The reaction CaCO3(s) CaO(s) + O2(g) is endothermic 298 K. The effect of adding a catalyst to the system at equilibrium will ________ (decrease, increase, have no effect on) the total quantity of CaCO3 once equilibrium is reestablished.

Q: The reaction CaCO3(s) CaO(s) + O2(g) is endothermic 298 K. The effect of increasing the temperature of the system at equilibrium will ________ (decrease, increase, have no effect on) the total quantity of CaCO3 once equilibrium is reestablished.

Q: The reaction below is heated from 20C to 90C, according to Le Chtelier's principle, there will be a net reaction from ________ to ________, and the brown color will become ________.N2O4(g) 2 NO2(g) H= + 57.2 kJcolorless brown

Q: The reaction CaCO3(s) CaO(s) + O2(g) is endothermic 298 K. The effect of increasing the total volume of the system at equilibrium will ________ (decrease, increase, have no effect on) the total quantity of CaCO3 once equilibrium is reestablished.

Q: The reaction CaCO3(s) CaO(s) + O2(g) is endothermic 298 K. The effect of increasing the partial pressure of O2 in the system at equilibrium will ________ (decrease, increase, have no effect on) the total quantity of CaCO3 once equilibrium is reestablished.

Q: According to Le Chtelier's principle, if the volume of the vessel containing the equilibrium system shown below is decreased, there will be an increase in the concentration of ________ and a decrease in the concentration of ________.H2(g) 2 H(g)

Q: The reaction CaCO3(s) CaO(s) + O2(g) is endothermic 298 K. The effect of adding additional CaO to the system at equilibrium will ________ (decrease, increase, have no effect on) the total quantity of CaCO3 once equilibrium is reestablished.

Q: If additional SCN- is added to the equilibrium system shown below, Le Chtelier's principle predicts a net reaction from ________ to ________, causing the red color to become ________.Fe3+(aq) + SCN-(aq) FeSCN2+(aq)yellow colorless red

Q: For the reaction A2 + 2 B3 2 AB3, the rate of the forward reaction is 0.25 M/s and the rate of the reverse reaction is 0.75 M/s. The reaction is not at equilibrium. In order to attain equilibrium the reaction must proceed in the ________ (forward, reverse) direction in order to achieve equilibrium.