Ph, Acids, Buffers
See Graph Question 70
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See Graph Question 71
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What molar ratio of acetic acid to sodium acetate is required to create a buffer solution having a pH of 4.89 at 25°C? Ka for HC2H3O2 is 1.8 × 10-5. a. 0.72 b. 1.4 c. 0.56 d. 2.0 e. 2.9
a. 0.72
What is the pH at the midpoint of the titration? a. 2.5 b. 3.7 c. 7.8 d. 11.5 e. 12.0
a. 2.5
What is the pH of the solution after the addition of 21.1 mL of potassium hydroxide? a. 3.143 b. 3.444 c. 3.463 d. 3.990 e. 6.711
a. 3.143
What is the pH of a 1.0L solution of 0.445 M hydrocyanic acid, HCN, after 0.191 mol of potassium cyanide, KCN, is added? (Ka of HCN = 4.0 x 10-10) a. 9.031 b. 9.125 c. 9.750 d. 9.765 e. 10.117
a. 9.031
If 0.40 g of solid NaOH is added to 1.0 liter of a buffer solution that is 0.10 M in CH3COOH and 0.10 M in NaCH3COO, how will the pH of the solution change? a. The pH increases from 4.74 to 4.83. b. The pH decreases from 7.00 to 4.83. c. The pH does not change. d. The pH decreases from 4.74 to 4.65. e. The pH increases from 4.74 to 7.00.
a. The pH increases from 4.74 to 4.83.
Consider a titration performed using acetic acid and aqueous ammonia. Which of the following statements is correct? a. The solution is buffered before and after the equivalence point. b. The equivalence point would be at pH > 10. c. Methyl orange (pH color range 3.1−4.4) could be a suitable indicator. d. There is a rapid change in pH throughout the entire titration. e. An acidic salt is present at the equivalence point.
a. The solution is buffered before and after the equivalence point.
Consider the titration of a strong acid with a weak base. Which of the following statements is incorrect? a. The solution is buffered only after the equivalence point. b. The equivalence point would be less than pH = 7.0. c. At the equivalence point, only water and an acidic salt are present. d. Methyl orange (pH color range 3.1−4.4) could be a suitable indicator. e. The titration of HNO3 with dimethylamine is an example.
a. The solution is buffered only after the equivalence point.
Which acid-base combination is depicted by this titration curve? (The marker is located at titrant volume where the titration solution pH equals 7.) see graph Q.102 a. Titration of a weak base with a strong acid. b. Titration of a weak acid with a strong base. c. Titration of a strong acid with a strong base. d. Titration of a strong base with a strong acid. e. Not enough information provided.
a. Titration of a weak base with a strong acid.
In the titration of a weak monoprotic acid with a strong monoprotic base, what is the pH at the equivalence point? a. above 7.00 b. below 7.00 c. exactly 7.00 d. cannot tell without a Ka for the acid
a. above 7.00
What is the pH of the above solution at the equivalence point? a. above 7.00 b. below 7.00 c. exactly 7.00
a. above 7.00
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 Ka NH4+ (from ammonia) 5.69 × 10-10 HC2H3O2 (acetic acid) 1.75 × 10-5 HF (hydrofluoric acid) 6.8 × 10-4 CH3CH2NH3+ (from ethylamine) 2.12 × 10-11 a. acetic acid b. hydrofluoric acid c. ethylamine d. none e. ammonia
a. acetic acid
When a solution of weak electrolyte is altered by adding one of its ions from another source, the ionization of the weak electrolyte is suppressed. This behavior is termed the ____. a. common ion effect b. buffer effect c. titration curve d. equivalence point e. partial neutralization effect
a. common ion effect
The pH curve below represents the titration of a ______. see graph Q.133 mL of 0.1 M base added a. strong acid with a strong base b. strong acid with a weak base c. weak acid with a strong base d. weak acid with a weak base
a. strong acid with a strong base
One of the following buffer solutions has pOH = 5.05. Which one? Hint: Solve the general problem rather than 5 specific problems. a. 0.10 M NH3 and 0.10 M NH4Cl b. 0.10 M NH3 and 0.20 M NH4Cl c. 0.20 M NH3 and 0.10 M NH4Cl d. 0.050 M NH3 and 0.20 M NH4Cl e. 0.20 M NH3 and 0.050 M NH4Cl
b. 0.10 M NH3 and 0.20 M NH4Cl
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 × 10-5. a. 40 g b. 0.31 g c. 1.0 g d. 0.000055 g e. 0.61 g
b. 0.31 g
Which of the following aqueous mixtures would make a good buffer system? a. 0.25 M HClO4 and 0.22 M NaClO4 b. 0.35 M NH4Br and 0.37 M NH3 c. 0.12 M HCN and 0.21 M HCl d. 0.11 M KOH and 0.29 M KCl e. 0.36 M HNO3 and 0.29 M KNO3
b. 0.35 M NH4Br and 0.37 M NH3
What is the pH of the solution before any sodium hydroxide is added? a. 0.196 b. 0.527 c. 0.726 d. 0.963 e. 2.125
b. 0.527
A solution that is 0.20 M in NH3 is also 0.30 M in NH4Cl. What is the [OH−] in this solution? a. 4.5 × 10^−6 M b. 1.2 × 10^−5 M c. 7.4 × 10^−5 M d. 6.4 × 10^−4 M e. 2.4 × 10^−7 M
b. 1.2 × 10^−5 M
What is the value of Kb for the weak base? a. 6.3 x 10^-6 b. 1.6 x 10^-9 c. 5.0 x 10^-4 d. 2.0 x 10^-11 e. 7.9 x 10^-13
b. 1.6 x 10^-9
Which of the following aqueous mixtures would make a good buffer system? a. 100.0mL of 0.25M HBr and 50.0mL of 0.22M NaOH b. 100.0mL of 0.35M NH3 and 50.0mL of 0.37M NaOH c. 100.0mL of 0.12M HCN and 100.0mL of 0.21M HCl d. 50.0mL of 0.11M KOH and 50.0mL of 0.29M KCl e. 100.0mL of 0.36M NaBr and 100.0mL of 0.29M KBr
b. 100.0mL of 0.35M NH3 and 50.0mL of 0.37M NaOH
If 50.00 mL of 0.1000 M NaOH is titrated with 0.1000 M HCl, what is the pH of the solution after 30.00 mL of HCl solution has been added? a. 13.00 b. 12.40 c. 12.60 d. 12.00 e. 12.80
b. 12.40
A solution is made by combining 500 mL of 0.10 M HF with 300 mL of 0.15 M NaF. What is the pH of the solution? a. 2.97 b. 3.10 c. 3.19 d. 3.22 e. 3.32
b. 3.10
What is the value of Ka for the weak acid? a. 1.3 x 10^-2 b. 3.2 x 10^-3 c. 1.8 x 10^-4 d. 3.1 x 10^-8 e. 6.3 x 10^-12
b. 3.2 x 10^-3
What is the pH of an aqueous solution containing CH3COOH and NaCH3COO in a molar ratio of 4.0 to 1.0? a. 4.37 b. 4.14 c. 9.25 d. 5.35 e. 4.74
b. 4.14
What is the pH of a solution that is 0.038 M in HA and also 0.0036 M in NaA? (Ka = 3.8 × 10-6) a. 8.45 b. 4.40 c. 6.44 d. 5.42 e. 7.18
b. 4.40
If 0.090 mole of solid NaOH is added to 1.0 liter of 0.180 M CH3COOH, what will be the pH of the resulting solution? Assume no volume change due to addition of NaOH. a. 4.51 b. 4.74 c. 5.08 d. 5.70 e. 5.94
b. 4.74
Calculate the pH of a solution prepared by adding 60.0 mL of 0.100 M NaOH to 100. mL of 0.100 M CH3COOH solution. a. 4.56 b. 4.92 c. 5.00 d. 5.08 e. 5.16
b. 4.92
What is the pH of a solution that is 0.30 M in aniline, C6H5NH2, and 0.15 M in anilinium chloride, C6H5NH3+Cl−? Aniline ionizes as follows. C6H5NH2 + H2O C6H5NH3+ + OH− a. 4.32 b. 4.92 c. 5.62 d. 5.74 e. 5.95
b. 4.92
A buffer solution is prepared by mixing 250. mL of 1.00 M CH3COOH with 500. mL of 0.500 M calcium acetate, Ca(CH3COO)2. Calculate the pH. a. 5.36 b. 5.05 c. 4.74 d. 4.58 e. 4.40
b. 5.05
Calculate the pH of 500. mL of 0.100 M acetic acid, CH3COOH, which also contains 0.100 mole of sodium acetate, NaCH3COO. a. 4.77 b. 5.05 c. 5.32 d. 5.68 e. 7.00
b. 5.05
Consider the titration of 300.0 mL of 0.410 M NH3 (Kb = 1.8 ×10-5) with 0.500 M HNO3. After 150.0 mL of 0.500 M HNO3 has been added, what is the pH of the solution? a. 4.94 b. 9.06 c. 6.06 d. 11.06 e. none of these
b. 9.06
Calculate the pH for a buffer solution prepared by mixing 100. mL of 0.60 M NH3 and 200. mL of 0.45 M NH4Cl. a. 8.65 b. 9.08 c. 9.87 d. 4.90 e. 6.62
b. 9.08
If 0.050 moles of gaseous HCl is bubbled in 1.0 liter of a solution that is 0.15 M in NH3 and 0.10 M in NH4Cl, what will be the pH of the resulting solution? a. 7.05 b. 9.08 c. 4.57 d. 9.43 e. 4.92
b. 9.08
When a weak base is titrated with a strong acid, the pH at the equivalence point is always ____. a. 7 b. < 7 c. > 7 d. < 1 e. > 4
b. < 7
Which of the following statements about buffers is false? a. A buffer resists changes in pH. b. A buffer always consists of a weak acid and a soluble ionic salt of the weak acid. c. A buffer solution can react with either H3O+ or OH− ions. d. Most body fluids contain natural buffer systems. e. Many medications are buffered to prevent digestive upset.
b. A buffer always consists of a weak acid and a soluble ionic salt of the weak acid.
Which of the following acids would be best to create a buffer with a pH of 3.75? a. HF, Ka = 7.2 x 10-4 b. C6H5COOH, Ka = 6.3 x 10-5 c. CH3COOH, Ka = 1.8 x 10-5 d. H2S, Ka1 = 1.0 x 10-7 e. HCN, Ka = 4.0 x 10-10
b. C6H5COOH, Ka = 6.3 x 10-5
What is the pH at the equivalence point? a. above 7.00 b. below 7.00 c. exactly 7.00 d. cannot tell without the Kb for the base
b. below 7.00
An aqueous solution contains 0.27 M ammonium chloride, NH4Cl. One liter of this solution could be converted into a buffer by the addition of: a. 0.13 mol HCl b. 0.26 mol KCl c. 0.26 mol NH3 d. 0.27 mol HBr e. 0.27 mol KOH
c. 0.26 mol NH3
An aqueous solution contains 0.26 M ammonia, NH3, One liter of this solution could be converted into a buffer by the addition of: a. 0.27 mol KOH b. 0.26 mol KCl c. 0.27 mol NH4Cl d. 0.27 mol HBr e. 0.13 mol KOH
c. 0.27 mol NH4Cl
What is the pH of the solution after the addition of 19.9 mL of sodium hydroxide? a. 0.779 b. 0.827 c. 1.079 d. 2.124 e. 2.424
c. 1.079
The equivalence point of the titration of an unknown acid with NaOH is at pH = 8.10. What would be the Ka for the best choice of an indicator for this titration? a. 10−2 b. 10−4 c. 10−8 d. 10−6 e. 10−7
c. 10−8
What is the pH of an aqueous solution that contains 0.226 M potassium hydrogen phosphate, K2HPO4, and 0.451 M potassium dihydrogen phosphate, KH2PO4? (Ka for H2PO4- = 6.2 x 10-8) a. 6.562 b. 6.862 c. 6.908 d. 7.208 e. 7.508
c. 6.908
What is the pH after 0.089 mol of HCl is added to the buffer solution? a. 8.787 b. 8.866 c. 9.073 d. 9.398 e. 9.723
c. 9.073
What is the pH of this buffer solution? a. 8.176 b. 8.439 c. 9.319 d. 9.398 e. 9.476
c. 9.319
Which one of the following combinations cannot produce a buffer solution? a. HNO2 and NaNO2 b. HCN and NaCN c. HClO4 and NaClO4 d. NH3 and (NH4)2SO4 e. NH3 and NH4Br
c. HClO4 and NaClO4
A(n) ____ solution contains a conjugate acid-base pair with both the acid and the base in reasonable concentrations. a. saturated b. electrolytic c. buffer d. titrated e. equivalence
c. buffer
What will be the pH at the equivalence point? a. above 7.00 b. below 7.00 c. exactly 7.00 d. cannot tell without the Ka for HI
c. exactly 7.00
The pH curve below represents the titration of a ______. `see graph Q.134 mL of 0.1 M base added a. strong acid with a weak base b. strong acid with a strong base c. weak acid with a weak base d. weak acid with a strong base
c. weak acid with a weak base
An aqueous solution contains 0.26 M hydrocyanic acid, HCN. One liter of this solution could be converted to a buffer by the addition of: a. 0.13 mol HBr b. 0.26 mol KBr c. 0.27 mol HBr d. 0.13 mol KOH e. 0.13 mol NH3
d. 0.13 mol KOH
What is the pH of a buffer solution that is 0.270 M in dimethylamine, (CH3)2NH, and 0.449 M in dimethylammonium chloride, (CH3)2NH2Cl? (Kb for (CH3)2NH = 5.9 x 10-4) a. 3.008 b. 3.450 c. 10.298 d. 10.550 e. 10.771
d. 10.550
What is the pH at the midpoint of the titration? a. 3.377 b. 8.318 c. 10.318 d. 10.623 e. 10.714
d. 10.623
What volume of sodium hydroxide is required to reach the equivalence point? a. 16.0 mL b. 20.0 mL c. 25.3 mL d. 40.0 mL e. 41.3 mL
d. 40.0 mL
Calculate the pH of a solution resulting from the addition of 50.0 mL of 0.30 M HNO3 to 50.0 mL of 0.30 M NH3. a. 4.92 b. 7.46 c. 6.18 d. 5.04 e. 8.30
d. 5.04
What is the pH at the midpoint of the titration? a. 1.7 b. 1.9 c. 3.3 d. 5.2 e. 6.5
d. 5.2
What is the pH of a solution that is 0.20 M in HCN and 0.15 M in KCN? a. 7.60 b. 8.40 c. 8.80 d. 9.27 e. 10.10
d. 9.27
What is the pH after 0.107 mol of NaOH is added to the buffer solution? a. 9.193 b. 9.319 c. 9.398 d. 9.602 e. 9.928
d. 9.602
The pH curve below represents the titration of a ______. see graph Q.132 mL of 0.1 M base added a. strong acid with a strong base b. strong acid with a weak base c. weak acid with a strong base d. weak acid with a weak base
d. weak acid with a weak base
What is the pH of the solution before the addition of any hydroiodic acid? a. 1.951 b. 3.377 c. 5.574 d. 10.623 e. 12.050
e. 12.050
If 40 mL of 0.10 M NaOH is added to 50 mL of 0.20 M HC2H3O2, what is the pH of the resulting solution at 25°C? Ka for HC2H3O2 is 1.8 × 10-5 at 25°C. a. 10.5 b. 4.3 c. 4.9 d. 2.7 e. 4.6
e. 4.6
What volume of potassium hydroxide is required to reach the equivalence point? a. 14.6 mL b. 24.8 mL c. 28.6 mL d. 32.4 mL e. 42.1 mL
e. 42.1 mL
Calculate the pH of a solution that is 0.050 M in HCN and 0.025 M in Ba(CN)2. a. 7.60 b. 8.80 c. 9.10 d. 10.20 e. 9.40
e. 9.40
Which titration curve could describe the titration of a solution of CH3COOH by addition of a solution of NH3? Q.94
see graph
Which of the following titration curves depicts the titration of a strong acid with a strong base? a. c. b. d.
see graphs Q.135
What is the pH of the solution resulting from the addition of 40.0 mL of 0.200 M HClO4 to 20.0 mL of 0.150 M NaOH? a. 1.08 b. 1.25 c. 1.36 d. 1.48 e. 1.67
a. 1.08
Calculate the pH of a solution prepared by adding 80.0 mL of 0.100 M NaOH solution to 100. mL of 0.100 M HNO3 solution. a. 1.95 b. 2.02 c. 2.08 d. 2.16 e. 2.24
a. 1.95
How many grams of KNO2 must be added to 5.00 liters of 0.67 M HNO2 solution to produce a buffer with pH = 3.15? Assume no change in volume. a. 181 g b. 3.15 g c. 270 g d. 53.6 g e. 315 g
a. 181 g
How much NH4Cl must be added to 2.00 liters of 0.200 M aqueous ammonia to give a solution with pH = 8.20? Assume no volume change due to the addition of NH4Cl. a. 246 g b. 166 g c. 2.25 g d. 123 g e. 14.6 g
a. 246 g
What is the pH of a solution which is 0.0400 M in formic acid, HCO2H, and 0.0600 M in sodium formate, NaHCOO? a. 3.92 b. 3.96 c. 4.00 d. 9.52 e. 4.08
a. 3.92
What is the pH of a buffer made by combining 175 mL of 0.33 M NaC2H3O2 with 126 mL of 0.48 M HC2H3O2? The Ka of acetic acid is 1.75 × 10-5. a. 4.74 b. 4.78 c. 5.79 d. 4.69 e. 5.24
a. 4.74
What ratio of NH4Cl/NH3 should be used to give a buffer with pH = 8.50? a. 5.7 b. 0.17 c. 0.76 d. 1.3 e. 4.2
a. 5.7
What is the pH of a solution that is 0.15 M in HOCl and 0.25 M NaOCl after 0.050 mol HCl/L has been bubbled into the solution? a. 7.46 b. 6.15 c. 6.98 d. 7.23 e. 7.93
a. 7.46
Consider the titrations of the pairs of aqueous acids and bases listed at the left. Which pair is incorrectly described (at the right) in terms of the acidic, basic, or neutral character of the solutions at the equivalence point? Acid-Base Pair / Character at Equivalence Point a. HClO + NaOH / acidic b. HNO3 + Ca(OH)2 / neutral c. CH3COOH + KOH / basic d. HCl + NH3 / acidic e. CH3COOH + NH3 / neutral
a. HClO + NaOH / acidic
What is the pH at the point in a titration at which 20.00 mL of 1.000 M KOH has been added to 25.00 mL of 1.000 M HBr? a. 1.67 b. 0.95 c. 3.84 d. 2.71 e. 1.22
b. 0.95
What is the pH of the solution resulting from the addition of 30.0 mL of 0.200 M HClO4 to 20.0 mL of 0.150 M NaOH? a. 1.00 b. 1.22 c. 1.36 d. 1.48 e. 1.67
b. 1.22
Calculate the pH of the solution resulting from the addition of 100.0 mL of 0.20 M HClO4 to 100.0 mL of 0.15 M NaOH. a. 1.3 b. 1.6 c. 7.0 d. 12.4 e. 12.7
b. 1.6
A certain weak base B has a base-ionization constant Kb of 2.4 × 10-4 at 25°C. If strong acid is added to a solution of B, at what pH will [B] = [BH+]? a. 8.5 b. 10.4 c. 7.0 d. 3.6 e. 5.5
b. 10.4
Which one of the following combinations is not a buffer solution? a. NH3 / (NH4)2SO4 b. HBr / KBr c. HCN / NaCN d. NH3 / NH4Br e. CH3COOH / NaCH3COO
b. HBr / KBr
Which acid / base pair would produce an acidic equivalence point? a. HCl / RbOH b. HCl / NH3 c. CH3COOH / KOH d. H2SO4 / Ca(OH)2 e. HNO3 / Ba(OH)2
b. HCl / NH3
Which of the following titrations could the following curve describe? ~see graph Q.86 a. NaOH added to HF b. HCl added to aqueous NH3 c. CH3COOH added to aqueous NH3 d. KOH added to HClO4 e. HNO3 added to NaOH
b. HCl added to aqueous NH3
Which of the following acid / base pairs used in a titration would produce an equivalence point at pH = 7.0? a. HI / NH3 b. HI / RbOH c. HNO2 / NH3 d. HClO3 / NH3 e. HCN / NaOH
b. HI / RbOH
Choose the response that includes all the following combinations that are buffer solutions and none that are not buffer solutions. All components are present in 0.10 M concentrations. I. HCN and NaCN II. NH3 and NH4Cl III. HNO3 and NH4NO3 IV. H2SO4 and Na2SO4 a. I, III, and IV b. I and II c. II, III, and IV d. III and IV e. I and III
b. I and II
The pH of a 0.03 M formic acid (HCOOH) solution is 2.63. If 0.03 M sodium formate (NaHCOO) is added, which of the following statements is true? a. The pH decreases. b. The equilibrium position is shifted to the left. c. The [H3O+] increases. d. The [HCOOH] decreases. e. None of these are true.
b. The equilibrium position is shifted to the left.
Consider the titration curve describing the titration of a strong acid by addition of a strong base. Which of the following statements is false? a. The equivalence point is at pH = 7.0. b. The pH is lower at the end of the titration than at the beginning. c. The pH increases rapidly around the equivalence point. d. At the equivalence point, the only species present are water and a neutral salt. e. The pH does not increase very rapidly at the beginning of the titration.
b. The pH is lower at the end of the titration than at the beginning.
Which indicator could be used to titrate aqueous NH3 with HCl solution? Acid Range Color pH Range Basic Range Color a. pink 1.2−2.8 yellow b. blue 3.4−4.6 yellow c. yellow 6.5−7.8 purple d. colorless 8.3−9.9 red e. none of these indicators
b. blue 3.4−4.6 yellow
What ratio of NaOCN/HOCN will produce a buffer with pH = 3.10? a. 0.50 b. 1.1 c. 0.44 d. 2.3 e. 1.4
c. 0.44
Calculate the [H3O+] of a solution that is 0.20 M in HF and 0.10 M in NaF. a. 3.2 × 10^−4 M b. 4.0 × 10^−6 M c. 1.4 × 10^−3 M d. 6.3 × 10^−5 M e. 5.0 × 10^−3 M
c. 1.4 × 10^−3 M
Calculate the ratio [NH3]/[NH4Cl] that gives a solution with pH = 9.48. a. 0.33 b. 3.0 c. 1.7 d. 0.61 e. 4.5
c. 1.7
What is the [H3O+] of a solution that is 0.010 M in aqueous NH3 and 0.030 M in NH4NO3? a. 7.2 × 10^−6 M b. 6.0 × 10^−6 M c. 1.7 × 10^−9 M d. 1.4 × 10^−9 M e. 1.2 × 10^−9 M
c. 1.7 × 10^−9 M
What is the [H3O+] in a solution resulting from mixing of 100. mL of 0.100 M HCN and 10.0 mL of 0.100 M KOH? a. 9.1 × 10^−3 M b. 5.7 × 10^−6 M c. 3.6 × 10^−9 M d. 8.2 × 10^−5 M e. 2.0 × 10^−8 M
c. 3.6 × 10^−9 M
The nonionized form of an acid indicator is yellow, and its anion is blue. The Ka of this indicator is 10−6. What will be the approximate pH range over which this indicator changes color? a. 3−5 b. 4−6 c. 5−7 d. 8−10 e. 9−11
c. 5−7
What is the pH at the equivalence point in the titration of 50.0 mL of 0.100 M hydrofluoric acid, HF, with 0.100 M NaOH? a. 5.88 b. 6.08 c. 7.92 d. 8.12 e. 8.56
c. 7.92
Calculate the pH of a solution resulting from the addition of 20.0 mL of 0.100 M HCl to 50.0 mL of 0.100 M NH3. a. 9.26 b. 4.91 c. 9.44 d. 4.60 e. 9.08
c. 9.44
When a weak acid is titrated with a strong base, the pH at the equivalence point is always ____. a. 7 b. < 7 c. > 7 d. < 1 e. > 4
c. > 7
Consider an indicator (KHIn = 6.3 × 10−6) that ionizes as shown below. Which of the following statements is false? HIn + H2O H3O+ + In− yellow blue a. The ionized form of the indicator results in a blue solution. b. In acidic solutions containing the indicator, we would expect predominantly yellow color. c. Adding a base to a solution containing this indicator will cause the color to become yellow. d. At pH = 10.0, a solution of this indicator will be blue. e. At pH = 3.0, most of the indicator is in the non-ionized form.
c. Adding a base to a solution containing this indicator will cause the color to become yellow.
Which of the following statements about indicators is false? a. An indicator is an organic dye. b. An indicator's color depends on the [H3O+]. c. Phenolphthalein is colorless when the pH > 8. d. Many acid-base indicators are weak acids. e. Some indicators are vegetable/plant dyes.
c. Phenolphthalein is colorless when the pH > 8.
Which of the following statements about titration curves is false? a. A titration curve for titrating a strong acid/strong base will always have an equivalence point at pH = 7.0. b. A titration curve shows how pH changes near the equivalence point. c. The end point on a titration curve is the point where chemically equivalence amounts of acid and base have reacted. d. In titration curves for weak acid/weak base, pH changes near the equivalence point are too small for color changes to be used. e. The equivalence point will be basic when titrating a weak acid with a strong base.
c. The end point on a titration curve is the point where chemically equivalence amounts of acid and base have reacted.
A buffer is prepared using 0.085 M formic acid and 0.085 M sodium formate. Which of the following statements is false? a. The addition of 0.02 M HCl will decrease the pH slightly. b. The addition of 0.02 M NaOH will increase the pH slightly. c. The formate ion can neutralize bases added to the buffer. d. The addition of 1.0 M HCl will cause the pH to drop significantly. e. Diluting the solution with pure water won't change the pH of the buffer.
c. The formate ion can neutralize bases added to the buffer.
Consider the titration of 30.0 mL of 0.0200 M nitrous acid, HNO2, by adding 0.0500 M aqueous ammonia to it. Which statement is true? The pH at the equivalence point ____. a. is greater than 7 b. is equal to 7 c. is less than 7 d. is less than 0.02 e. zero
c. is less than 7
Which is the best indicator for the titration of HCl solution with NaOH solution, i.e. the most nearly ideal one? Acid Range Color pH Range Basic Range Color a. pink 1.2−2.8 yellow b. blue 3.4−4.6 yellow c. yellow 6.5−7.8 purple d. colorless 9.9−11.1 red e. none of these indicators
c. yellow 6.5−7.8 purple
Calculate the ratio [CH3COOH]/[NaCH3COO] that gives a solution with pH = 5.00. [CH3COOH]/[NaCH3COO] ____. a. 0.28 b. 0.36 c. 0.44 d. 0.56 e. 0.63
d. 0.56
How many moles of NH4Cl must be added to 1.00 liter of 0.010 M aqueous NH3 to adjust the pH to 10.00? a. 3.6 × 10^−5 mol b. 3.6 × 10^−3 mol c. 2.7 × 10^−3 mol d. 1.8 × 10^−3 mol e. 1.8 × 10^−2 mol
d. 1.8 × 10^−3 mol
The equivalence point of the titration of an unknown base with HCl is at pH = 5.90. What would be the Ka for the best choice of an indicator for this titration? a. 10−2 b. 10−4 c. 10−8 d. 10−6 e. 10−7
d. 10−6
Calculate the pH of a solution prepared by adding 115 mL of 0.100 M NaOH to 100. mL of 0.100 M HNO3 solution. a. 11.60 b. 11.68 c. 11.76 d. 11.84 e. 11.92
d. 11.84
Calculate the pH of the solution resulting from the addition of 30.0 mL of 0.200 M HClO4 to 60.0 mL of 0.150 M NaOH. a. 1.47 b. 7.00 c. 11.88 d. 12.52 e. 13.06
d. 12.52
It is desired to buffer a solution at pH = 4.30. What molar ratio of CH3COOH to NaCH3COO should be used? a. 1.2/1 b. 0.8/1 c. 0.12/1 d. 2.8/1 e. 6.2/1
d. 2.8/1
Calculate the pH for a buffer solution prepared by mixing 100. mL of 0.10 M HF and 200. mL of 0.10 M KF. a. 2.82 b. 2.96 c. 3.32 d. 3.44 e. 3.53
d. 3.44
A buffer solution is prepared by mixing 250. mL of 1.00 M HNO2 with 500. mL of 0.500 M calcium nitrite, Ca(NO2)2. Calculate the pH. a. 4.43 b. 3.35 c. 3.05 d. 3.65 e. 4.88
d. 3.65
Calculate the mass of solid NaCH3COO that must be added to 1.0 liter of 0.20 M CH3COOH solution so that the pH of the resulting solution will be 5.00. Assume no volume change due to addition of solid NaCH3COO. a. 15 g b. 20 g c. 25 g d. 30 g e. 35 g
d. 30 g
If 400. mL of 0.100 M CH3COOH and 200. mL of 0.100 M NaCH3COO solutions are mixed, what is the pH of the resulting solution? a. 3.09 b. 3.33 c. 3.78 d. 4.44 e. 4.60
d. 4.44
What is the pH of the solution resulting from the addition of 25.0 mL of 0.0100 M NaOH solution to 40.0 mL of 0.0100 M acetic acid, CH3COOH? a. 4.54 b. 4.52 c. 4.94 d. 4.96 e. 5.17
d. 4.96
Calculate the pH of a solution that is 0.15 M in HOCl and 0.25 M in NaOCl. a. 7.23 b. 8.28 c. 8.06 d. 7.68 e. 9.10
d. 7.68
A solution is initially 0.100 M in HOCl and 0.300 M in NaOCl. What is the pH if 0.030 mol of solid NaOH is added to 1.00 L of this solution? Assume no volume change. a. 5.24 b. 5.38 c. 8.02 d. 8.13 e. 9.06
d. 8.13
Calculate the pH of a solution that is 0.20 M in sodium hypobromite and 0.10 M in hypobromous acid. a. 4.15 b. 4.45 c. 8.60 d. 8.90 e. 8.30
d. 8.90
If 100. mL of 0.030 M HCl solution is added to 100. mL of buffer solution which is 0.10 M in NH3 and 0.10 M in NH4Cl, what will be the pH of the new solution? a. 5.01 b. 4.48 c. 7.88 d. 8.99 e. 9.52
d. 8.99
Consider a buffer consisting of 0.75 M NH3 and 0.50 M NH4Cl. If 0.10 M H2SO4 is added to the solution with no change in volume, what is the resulting pH? a. 4.56 b. 9.44 c. 9.29 d. 9.16 e. 4.84
d. 9.16
What is the pH of a solution that is 0.080 M in aqueous ammonia and 0.040 M in NH4Cl? a. 2.92 b. 4.44 c. 7.00 d. 9.56 e. 11.08
d. 9.56
Which of the following titrations could the following curve describe? ~see graph Q. 85 a. KOH added to HNO3 b. HCl added to aqueous NH3 c. HNO3 added to KOH d. NaOH added to CH3COOH e. CH3COOH added to aqueous KOH
d. NaOH added to CH3COOH
Which indicator could be used to titrate CH3COOH with NaOH solution? Acid Range Color pH Range Basic Range Color a. pink 1.2−2.8 yellow b. blue 3.4−4.6 yellow c. yellow 6.5−7.8 purple d. colorless 8.3−9.9 red e. none of these indicators
d. colorless 8.3−9.9 red
When a weak base is titrated with a weak acid, the pH at the equivalence point ____. a. 7 b. is always less than 7 c. is always greater than 7 d. depends on the value of Kb for the base and Ka for the acid e. zero
d. depends on the value of Kb for the base and Ka for the acid
The nonionized form of an acid indicator is yellow, and its anion is blue. The Ka of this indicator is 10−5. What will be the color of the indicator in a solution of pH 5? a. red b. orange c. yellow d. green e. blue
d. green
When a strong base is titrated with a strong acid, the pH at the equivalence point a. is greater than 7. b. is less than 7. c. depends on the value of Kb for the base and Ka for the acid. d. is equal to 7. e. zero
d. is equal to 7.
What is the [H3O+] of a solution that is 0.0100 M in HOCl and 0.0300 M in NaOCl? a. 2.14 × 10^−7 M b. 1.45 × 10^−7 M c. 7.41 × 10^−8 M d. 2.29 × 10^−8 M e. 1.17 × 10^−8 M
e. 1.17 × 10^−8 M
What is the pH of a 0.22 M HOCN solution containing 0.44 M NaOCN? a. 3.10 b. 3.16 c. 3.46 d. 2.80 e. 3.77
e. 3.77
Calculate the pH of a solution which is 0.400 M in HNO2 and 1.875 M in Ca(NO2)2. a. 3.64 b. 4.06 c. 4.87 d. 5.68 e. 4.32
e. 4.32
If 100. mL of 0.040 M NaOH solution is added to 100. mL of solution which is 0.10 M in CH3COOH and 0.10 M in NaCH3COO, what be will the pH of the new solution? a. 4.74 b. 4.81 c. 4.89 d. 5.00 e. 5.11
e. 5.11
If 0.040 moles of solid NaOH is added to 1.0 liter of a solution that is 0.10 M in NH3 and 0.20 M in NH4Cl, what will be the pH of the resulting solution? Assume no volume change due to the addition of the NaOH. a. 4.80 b. 8.95 c. 5.05 d. 8.65 e. 9.20
e. 9.20
If 0.10 mole of HCl is bubbled into 1.0 liter of 0.25 M NH3 solution, what will be the pH of the resulting solution? a. 9.08 b. 4.56 c. 9.68 d. 4.92 e. 9.44
e. 9.44
What is the pH of a solution containing aqueous ammonia and ammonium nitrate in a molar ratio of 5.0 to 3.0? a. 4.52 b. 4.96 c. 9.04 d. 9.26 e. 9.48
e. 9.48
Consider the titration of a weak acid with a strong base. Which of the following statements is incorrect? a. The solution is buffered before the equivalence point. b. The equivalence point would be greater than pH = 7.0. c. At the equivalence point, only water and a basic salt are present. d. KOH added to formic acid is an example of this. e. Methyl orange (pH color range 3.1−4.4) could be a suitable indicator.
e. Methyl orange (pH color range 3.1−4.4) could be a suitable indicator.
Which response is false? An acid-base indicator ____. a. might be an acid b. might have only one highly colored form c. might be a base d. might have two highly colored forms e. can be non-polar
e. can be non-polar
Which indicator could be used to titrate aqueous ammonia with CH3COOH? Acid Range Color pH Range Basic Range Color a. pink 1.2−2.8 yellow b. blue 3.4−4.6 yellow c. yellow 6.5−7.8 purple d. colorless 8.3−9.9 red e. none of these indicators
e. none of these indicators
Which titration curve could describe the titration of a solution of NH2OH by addition of a solution of HNO3? Q.88
see graph
Which titration curve could describe the titration of a solution of CH3COOH by addition of a solution of KOH?
see graph Q.87
