Question 1

Which of the following is TRUE?

Accepted Answer

A)  An effective buffer has a [base]/[acid] ratio in the range of 10 - 100. 
B)  A buffer is most resistant to pH change when [acid] = [conjugate base] 
C)  An effective buffer has very small absolute concentrations of acid and conjugate base. 
D)  A buffer can not be destroyed by adding too much strong base. It can only be destroyed by adding too much strong acid. 
E)  None of the above are true. 
A)  An effective buffer has a [base]/[acid] ratio in the range of 10 - 100. 
B)  A buffer is most resistant to pH change when [acid] = [conjugate base] 
C)  An effective buffer has very small absolute concentrations of acid and conjugate base. 
D)  A buffer can not be destroyed by adding too much strong base. It can only be destroyed by adding too much strong acid. 
E)  None of the above are true.

Question 2

How many milliliters of 0.120 M NaOH are required to titrate 50.0 mL of 0.0998 M formic acid to the equivalence point? The Ka of formic acid is 1.8 × 10-4.

Accepted Answer

A)  3.82 mL 
B)  50.0 mL 
C)  41.6 mL 
D)  60.1 mL 
E)  3.57 mL 
A)  3.82 mL 
B)  50.0 mL 
C)  41.6 mL 
D)  60.1 mL 
E)  3.57 mL

Question 3

Calculate the pH of a buffer that is 0.040 M HF and 0.080 M NaF.The Ka for HF is 3.5 × 10-4.

Accepted Answer

A)  2.06 
B)  4.86 
C)  3.16 
D)  3.46 
E)  3.76 
A)  2.06 
B)  4.86 
C)  3.16 
D)  3.46 
E)  3.76

Question 4

Explain the common ion effect with respect to molar solubility.

Accepted Answer

The common ion effect occurs when a solu

Question 5

A 1.0 L buffer solution is 0.050 M HC2H3O2 and 0.250 M KC2H3O2.Which of the following actions will destroy the buffer?

Accepted Answer

A)  adding 0.050 moles of NaOH 
B)  adding 0.050 moles of HCl 
C)  adding 0.050 moles of HC2H3O2 
D)  adding 0.050 moles of KC2H3O2 
E)  All of the above will destroy the buffer. 
A)  adding 0.050 moles of NaOH 
B)  adding 0.050 moles of HCl 
C)  adding 0.050 moles of HC2H3O2 
D)  adding 0.050 moles of KC2H3O2 
E)  All of the above will destroy the buffer.

Question 6

What is the pH of a solution made by mixing 5.00 mL of 0.10 M acetic acid with 5.00 mL of 0.10 M KOH? Assume that the volumes of the solutions are additive.Ka = 1.8 × 10-5 for CH3CO2H.

Accepted Answer

A)  5.28 
B)  7.00 
C)  8.72 
D)  10.02 
A)  5.28 
B)  7.00 
C)  8.72 
D)  10.02

Question 7

You have 2.00 L of a buffer solution which is composed of 0.250 M HClO and 0.650 M KClO.Calculate the pH of the solution after the addition of 265 mL of 1.00 M HCl.The Ka for HClO is 3.0 × 10-8.

Accepted Answer

A)  7.65 
B)  11.65 
C)  7.89 
D)  11.14 
E)  4.66 
A)  7.65 
B)  11.65 
C)  7.89 
D)  11.14 
E)  4.66

Question 8

A 100.0 mL sample of 0.10 M Ca(OH)2 is titrated with 0.10 M HBr.Determine the pH of the solution before the addition of any HBr.

Accepted Answer

A)  12.86 
B)  13.00 
C)  13.30 
D)  0.70 
E)  1.00 
A)  12.86 
B)  13.00 
C)  13.30 
D)  0.70 
E)  1.00

Question 9

What is the approximate pH at the equivalence point of a weak acid-strong base titration if 25 mL of aqueous formic acid requires 29.80 mL of 0.1567 M NaOH? Ka =1.8 × 10-4 for formic acid.

Accepted Answer

A)  2.24 
B)  5.66 
C)  8.34 
D)  11.76 
A)  2.24 
B)  5.66 
C)  8.34 
D)  11.76

Question 10

A 100.0 mL sample of 0.10 M NH3 is titrated with 0.10 M HNO3.Determine the pH of the solution before the addition of any HNO3.The Kb of NH3 is 1.8 × 10-5.

Accepted Answer

A)  4.74 
B)  9.26 
C)  11.13 
D)  13.00 
E)  12.55 
A)  4.74 
B)  9.26 
C)  11.13 
D)  13.00 
E)  12.55

Question 11

Calculate the pH of a solution formed by mixing 100.0 mL of 0.20 M HClO with 200.0 mL of 0.30 M KClO.The Ka for HClO is 2.9 × 10-8.

Accepted Answer

A)  5.99 
B)  8.01 
C)  7.54 
D)  7.06 
E)  6.46 
A)  5.99 
B)  8.01 
C)  7.54 
D)  7.06 
E)  6.46

Question 12

What is the pH of a solution prepared by mixing 48.00 mL of 0.25 M H3PO4 with 85.00 mL of 0.85M LiH2PO4? Assume that the volume of the solutions are additive and that Ka = 7.1 × 10-3 for H3PO4.

Accepted Answer

A)  11.07 
B)  2.93 
C)  4.31 
D)  8.63 
A)  11.07 
B)  2.93 
C)  4.31 
D)  8.63

Question 13

When titrating a weak monoprotic acid with NaOH at 25°C,the

Accepted Answer

A)  pH will be less than 7 at the equivalence point. 
B)  pH will be equal to 7 at the equivalence point. 
C)  pH will be greater than 7 at the equivalence point. 
D)  titration will require more moles of base than acid to reach the equivalence point. 
E)  titration will require more moles of acid than base to reach the equivalence point. 
A)  pH will be less than 7 at the equivalence point. 
B)  pH will be equal to 7 at the equivalence point. 
C)  pH will be greater than 7 at the equivalence point. 
D)  titration will require more moles of base than acid to reach the equivalence point. 
E)  titration will require more moles of acid than base to reach the equivalence point.

Question 14

What is the pH of a solution prepared by mixing 50.00 mL of 0.10 M methylamine,CH3NH2,with 15.00 mL of 0.10 M methylammonium chloride,CH3NH3Cl? Assume that the volume of the solutions are additive and that Kb = 3.70 × 10-4 for methylamine.

Accepted Answer

A)  10.04 
B)  10.57 
C)  11.09 
D)  11.78 
A)  10.04 
B)  10.57 
C)  11.09 
D)  11.78

Question 15

A solution containing CaCl2 is mixed with a solution of Li2C2O4 to form a solution that is 2.1 × 10-5 M in calcium ion and 4.75 × 10-5 M in oxalate ion.What will happen once these solutions are mixed? Ksp (CaC2O4)= 2.3 × 10-9.

Accepted Answer

A)  A precipitate will form since Q > Ksp for calcium oxalate. 
B)  Nothing will happen since both calcium chloride and lithium oxalate are soluble compounds. 
C)  Nothing will happen since calcium oxalate is extremely soluble. 
D)  Nothing will happen since Ksp > Q for all possible precipitants. 
E)  There is not enough information to determine. 
A)  A precipitate will form since Q > Ksp for calcium oxalate. 
B)  Nothing will happen since both calcium chloride and lithium oxalate are soluble compounds. 
C)  Nothing will happen since calcium oxalate is extremely soluble. 
D)  Nothing will happen since Ksp > Q for all possible precipitants. 
E)  There is not enough information to determine.

Question 16

What is the approximate pH at the equivalence point of a weak acid-strong base titration if 25 mL of aqueous hydrofluoric acid requires 30.00 mL of 0.400 M NaOH? Ka = 6.76 × 10-4 for HF.

Accepted Answer

A)  1.74 
B)  5.75 
C)  8.25 
D)  12.26 
A)  1.74 
B)  5.75 
C)  8.25 
D)  12.26

Question 17

A solution is prepared by dissolving 0.23 mol of nitrous acid and 0.27 mol of sodium nitrite in water sufficient to yield 1.00 L of solution.The addition of 0.05 mol of NaOH to this buffer solution causes the pH to increase slightly.The pH does not increase drastically because the NaOH reacts with the ________ present in the buffer solution.The Ka of nitrous acid is 4.5 × 10-4.

Accepted Answer

A)  H2O 
B)  H3O+ 
C)  nitrite 
D)  nitrous acid 
E)  This is a buffer solution: the pH does not change upon addition of acid or base. 
A)  H2O 
B)  H3O+ 
C)  nitrite 
D)  nitrous acid 
E)  This is a buffer solution: the pH does not change upon addition of acid or base.

Question 18

Consider the Ksp values for two compounds: MZ,Ksp = 1.5 × 10-20 and MZ2,Ksp = 1.5 × 10-20.Why don't these compounds have the same molar solubility?

Accepted Answer

These two compounds have the same solubi

Question 19

A 100.0 mL sample of 0.10 M Ca(OH)2 is titrated with 0.10 M HBr.Determine the pH of the solution after the addition of 400.0 mL HBr.

Accepted Answer

A)  1.00 
B)  1.40 
C)  1.22 
D)  1.30 
E)  2.11 
A)  1.00 
B)  1.40 
C)  1.22 
D)  1.30 
E)  2.11

Question 20

Determine the molar solubility of AgBr in a solution containing 0.200 M NaBr.Ksp (AgBr)= 7.7 × 10-13.

Accepted Answer

A)  8.8 × 10-7 M 
B)  1.54 × 10-13 M 
C)  5.8 × 10-5 M 
D)  3.8 × 10-12 M 
E)  0.200 M 
A)  8.8 × 10-7 M 
B)  1.54 × 10-13 M 
C)  5.8 × 10-5 M 
D)  3.8 × 10-12 M 
E)  0.200 M

Exam 18: Aqueous Ionic Equilibrium

Which of the following is TRUE?

How many milliliters of 0.120 M NaOH are required to titrate 50.0 mL of 0.0998 M formic acid to the equivalence point? The Ka of formic acid is 1.8 × 10-4.

Calculate the pH of a buffer that is 0.040 M HF and 0.080 M NaF.The Ka for HF is 3.5 × 10-4.

Explain the common ion effect with respect to molar solubility.

A 1.0 L buffer solution is 0.050 M HC2H3O2 and 0.250 M KC2H3O2.Which of the following actions will destroy the buffer?

What is the pH of a solution made by mixing 5.00 mL of 0.10 M acetic acid with 5.00 mL of 0.10 M KOH? Assume that the volumes of the solutions are additive.Ka = 1.8 × 10-5 for CH3CO2H.

You have 2.00 L of a buffer solution which is composed of 0.250 M HClO and 0.650 M KClO.Calculate the pH of the solution after the addition of 265 mL of 1.00 M HCl.The Ka for HClO is 3.0 × 10-8.

A 100.0 mL sample of 0.10 M Ca(OH)2 is titrated with 0.10 M HBr.Determine the pH of the solution before the addition of any HBr.

What is the approximate pH at the equivalence point of a weak acid-strong base titration if 25 mL of aqueous formic acid requires 29.80 mL of 0.1567 M NaOH? Ka =1.8 × 10-4 for formic acid.

A 100.0 mL sample of 0.10 M NH3 is titrated with 0.10 M HNO3.Determine the pH of the solution before the addition of any HNO3.The Kb of NH3 is 1.8 × 10-5.

Calculate the pH of a solution formed by mixing 100.0 mL of 0.20 M HClO with 200.0 mL of 0.30 M KClO.The Ka for HClO is 2.9 × 10-8.

What is the pH of a solution prepared by mixing 48.00 mL of 0.25 M H3PO4 with 85.00 mL of 0.85M LiH2PO4? Assume that the volume of the solutions are additive and that Ka = 7.1 × 10-3 for H3PO4.

When titrating a weak monoprotic acid with NaOH at 25°C,the

What is the pH of a solution prepared by mixing 50.00 mL of 0.10 M methylamine,CH3NH2,with 15.00 mL of 0.10 M methylammonium chloride,CH3NH3Cl? Assume that the volume of the solutions are additive and that Kb = 3.70 × 10-4 for methylamine.

A solution containing CaCl2 is mixed with a solution of Li2C2O4 to form a solution that is 2.1 × 10-5 M in calcium ion and 4.75 × 10-5 M in oxalate ion.What will happen once these solutions are mixed? Ksp (CaC2O4)= 2.3 × 10-9.

What is the approximate pH at the equivalence point of a weak acid-strong base titration if 25 mL of aqueous hydrofluoric acid requires 30.00 mL of 0.400 M NaOH? Ka = 6.76 × 10-4 for HF.

Consider the Ksp values for two compounds: MZ,Ksp = 1.5 × 10-20 and MZ2,Ksp = 1.5 × 10-20.Why don't these compounds have the same molar solubility?

A 100.0 mL sample of 0.10 M Ca(OH)2 is titrated with 0.10 M HBr.Determine the pH of the solution after the addition of 400.0 mL HBr.

Determine the molar solubility of AgBr in a solution containing 0.200 M NaBr.Ksp (AgBr)= 7.7 × 10-13.

Essentials: Units, Measurements, and Problem Solving

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Crystalline Solids and Modern Materials

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How many milliliters of 0.120 M NaOH are required to titrate 50.0 mL of 0.0998 M formic acid to the equivalence point? The K_a of formic acid is 1.8 × 10^-4.

Calculate the pH of a buffer that is 0.040 M HF and 0.080 M NaF.The K_a for HF is 3.5 × 10^-4.

A 1.0 L buffer solution is 0.050 M HC₂H₃O₂ and 0.250 M KC₂H₃O₂.Which of the following actions will destroy the buffer?

What is the pH of a solution made by mixing 5.00 mL of 0.10 M acetic acid with 5.00 mL of 0.10 M KOH? Assume that the volumes of the solutions are additive.K_a = 1.8 × 10^-5 for CH₃CO₂H.

You have 2.00 L of a buffer solution which is composed of 0.250 M HClO and 0.650 M KClO.Calculate the pH of the solution after the addition of 265 mL of 1.00 M HCl.The K_a for HClO is 3.0 × 10^-8.

A 100.0 mL sample of 0.10 M Ca(OH)₂ is titrated with 0.10 M HBr.Determine the pH of the solution before the addition of any HBr.

What is the approximate pH at the equivalence point of a weak acid-strong base titration if 25 mL of aqueous formic acid requires 29.80 mL of 0.1567 M NaOH? K_a =1.8 × 10^-4 for formic acid.

A 100.0 mL sample of 0.10 M NH₃ is titrated with 0.10 M HNO₃.Determine the pH of the solution before the addition of any HNO₃.The K_b of NH₃ is 1.8 × 10^-5.

Calculate the pH of a solution formed by mixing 100.0 mL of 0.20 M HClO with 200.0 mL of 0.30 M KClO.The K_a for HClO is 2.9 × 10^-8.

What is the pH of a solution prepared by mixing 48.00 mL of 0.25 M H₃PO₄ with 85.00 mL of 0.85M LiH₂PO₄? Assume that the volume of the solutions are additive and that K_a = 7.1 × 10^-3 for H₃PO₄.

What is the pH of a solution prepared by mixing 50.00 mL of 0.10 M methylamine,CH₃NH₂,with 15.00 mL of 0.10 M methylammonium chloride,CH₃NH₃Cl? Assume that the volume of the solutions are additive and that K_b = 3.70 × 10^-4 for methylamine.

A solution containing CaCl₂ is mixed with a solution of Li₂C₂O₄ to form a solution that is 2.1 × 10^-5 M in calcium ion and 4.75 × 10^-5M in oxalate ion.What will happen once these solutions are mixed? K_sp (CaC₂O₄)= 2.3 × 10^-9.

What is the approximate pH at the equivalence point of a weak acid-strong base titration if 25 mL of aqueous hydrofluoric acid requires 30.00 mL of 0.400 M NaOH? K_a = 6.76 × 10^-4 for HF.

Consider the K_sp values for two compounds: MZ,K_sp = 1.5 × 10^-20 and MZ₂,K_sp = 1.5 × 10^-20.Why don't these compounds have the same molar solubility?

A 100.0 mL sample of 0.10 M Ca(OH)₂ is titrated with 0.10 M HBr.Determine the pH of the solution after the addition of 400.0 mL HBr.

Determine the molar solubility of AgBr in a solution containing 0.200 M NaBr.K_sp (AgBr)= 7.7 × 10^-13.