A 1.50 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 0.0500 moles of solid NaOH. Assume no volume change upon the addition of base. The K_a for HF is 3.5 × 10^-4.

A)3.63

B)3.34

C)3.46

D)2.89

E)3.57

Answer: E

Which of the following acids is the WEAKEST? The acid is followed by its K_a value.

A)H COOH, 1.8 × 10^-4

B)HNO₂, 4.6 × 10^-4

C)HClO₂, 1.1 × 10^-2

D)HF, 3.5 × 10^-4

E)HCN, 4.9 × 10^-10

Answer E

Calculate the pOH in an aqueous solution with a pH of 7.85 at 25°C.

A)5.15

B)7.15

C)6.15

D)8.15

E)4.15

Answer C

The pH of an aqueous solution at 25.0°C is 10.66. What is the molarity of H⁺ in this solution?

A)4.6 × 10¹⁰

B)4.6 × 10^-4

C)2.2 × 10^-11

D)1.1 × 10^-13

E)3.3

Answer C

Consider a reaction that has a negative ΔH and a negative ΔS. Which of the following statements is TRUE?

A)This reaction will be nonspontaneous only at high temperatures.

B)This reaction will be nonspontaneous at all temperatures.

C)This reaction will be spontaneous at all temperatures.

D)This reaction will be spontaneous only at high temperatures.

E)It is not possible to determine without more information.

Answer A

Calculate the concentration of H₃O⁺ in a solution that contains 5.5 × 10^-5 M OH^- at 25°C. Identify the solution as acidic, basic, or neutral.

A)5.5 × 10^-10 M,neutral

B)1.8 × 10^-10 M,basic

C)9.2 × 10^-1 M, basic

D)1.8 × 10^-10 M, acidic

E)9.2 × 10^-1 M, acidic

Answer B

A buffer solution is 0.100 M in both HC₇H₅O₂ and LiC₇H₅O₂ and has a pH of 4.19. Which of the following pH values would you expect from the addition of a small amount of a dilute solution of a strong base?

A)5.69

B)4.49

C)3.69

D)3.89

E)There is not enough information to determine.

Answer B

Calculate the pH of a solution formed by mixing 150.0 mL of 0.10 M HC₇H₅O₂ with 100.0 mL of 0.30 M NaC₇H₅O₂. The K_a for HC₇H₅O₂ is 6.5 × 10^-5.

A)4.31

B)9.69

C)4.19

D)10.51

E)4.49

Answer E

Calculate the pH of a buffer that is 0.158 M HClO and 0.099 M NaClO. The K_a for HClO is 2.9 × 10^-8.

A)3.77

B)7.54

C)6.67

D)6.46

E)7.33

Answer E

A 100.0 mL sample of 0.18 M HClO₄ is titrated with 0.27 M LiOH. Determine the pH of the solution after the addition of 100.0 mL of LiOH.

A)0.87

B)12.6 5

C)12.95

D)13.13

E)1.35

Answer B

Calculate the pH of a solution formed by mixing 250.0 mL of 0.15 M HCHO₂ with 100.0 mL of 0.20 M LiCHO₂. The K_a for HCHO₂ is 1.8 × 10^-4.

A)10.13

B)3.87

C)3.47

D)10.53

E)3.74

Answer C

Calculate the pH of a solution that contains 3.9 x 10^-5 M H₃O⁺ at 25°C.

A)0.59

B)5.41

C)8.59

D)9.59

E)4.41

Answer E

Calculate the pH of a buffer that is 0.105 M HC₂H₃O₂ and 0.146 M KC₂H₃O₂. The K_a for HC₂H₃O₂ is 1.8 × 10^-5.

A)9.11

B)9.26

C)4.60

D)4.89

E)4.74

Answer D

Calculate the pOH of a solution that contains 2.4 × 10^-5 M H₃O⁺ at 25°C.

A)2.40

B)9.38

C)4.62

D)5.62

E)8.38

Answer B

Which of the following acids will have the strongest conjugate base?

A)HClO₄

B)HCN

C)HNO₃

D)HCl

E)HI

Answer B

A 100.0 mL sample of 0.18 M HClO₄ is titrated with 0.27 M LiOH. Determine the pH of the solution after the addition of 30.0 mL of LiOH.

A)1.12

B)2.86

C)1.21

D)2.00

E)0.86

Answer A

Determine the pH of a 0.023 M HNO₃ solution.

A)12.36

B)2.30

C)1.64

D)2.49

E)3.68

Answer C

Calculate the hydroxide ion concentration in an aqueous solution with a pH of 9.85 at 25°C.

A)6.5 × 10^-5 M

B)1.4 × 10^-10 M

C)8.7 × 10^-10 M

D)7.1 × 10^-5 M

E)4.2 × 10^-10 M

Answer D

Determine the [OH^-] concentration of a 0.123 M Sr(OH)₂ solution at 25°C.

A)0.0615 M

B)8.13 x 10^-14 M

C)0.123 M

D)4.06 x 10^-14 M

E)0.246 M

Answer E

Which of the following is a triprotic acid?

A)CCl₄

B)H₃PO₄

C)H₂SO₄

D)HI

E)HC₂H₃O₂

Answer B

Calculate the pOH of a solution that contains 7.8 x 10^-6 M OH^- at 25°C.

A)8.89

B)9.64

C)1.28

D)5.11

E)12.72

Answer D

If the pKa of HCHO₂ is 3.74 and the pH of an HCHO₂/NaCHO₂ solution is 3.11, which of the following is TRUE?

A)HCHO₂] << [NaCHO₂]

B)[HCHO₂] > [NaCHO₂]

C)[HCHO₂] = [NaCHO₂]

D)[HCHO₂] < [NaCHO₂]

E)It is not possible to make a buffer of this pH from HCHO₂ and NaCHO₂.

Answer B

Determine the molar solubility of Fe(OH)₂ in pure water. K_sp for Fe(OH)₂)= 4.87 × 10^-17.

A)2.44 × 10^-17 M

B)2.30 × 10^-6 M

C)3.65 × 10^-6 M

D)1.62 × 10^-17 M

E)4.03 × 10^-9 M

Answer B

Calculate the hydroxide ion concentration in an aqueous solution that contains 3.50 × 10^-4 M in hydronium ion.

A)2.86 × 10^-11 M

B)2.86 × 10^-3 M

C)3.50 × 10^-11 M

D)2.86 × 10^-10 M

Answer A

A 1.00 L buffer solution is 0.250 M in HF and 0.250 M in LiF. Calculate the pH of the solution after the addition of 0.150 moles of solid LiOH. Assume no volume change upon the addition of base. The K_a for HF is 3.5 × 10^-4.

A)4.24

B)4.06

C)3.46

D)3.63

E)2.85

Answer B

Calculate the pH of a buffer that is 0.058 M HF and 0.058 M LiF. The K_a for HF is 3.5 × 10^-4.

A)10.54

B)9.31

C)4.69

D)3.46

E)2.86

Answer D

Which of the following is a polyprotic acid?

A)H₂SO₄

B)CCl₄

C)HCN

D)HI

E)HC₂H₃O₂

Answer A

Place the following in order of increasing acid strength.

HBrO₂ HBrO₃ HBrO HBrO₄

_{A)HBrO2 < HBrO4 < HBrO < HBrO3}

_{B)HBrO < HBrO2 < HBrO3 < HBrO4}

_{C)HBrO4 < HBrO2 < HBrO3 < HBrO}

D)HBrO₂ < HBrO₃ < HBrO₄ < HBrO

E)HBrO < HBrO₄ < HBrO₃ < HBrO₂

Answer B

What is the hydronium ion concentration of a 0.150 M hypochlorous acid solution with k_a=3.5 x 10^-8. The equation for the dissociation of hypochlorous acid is:

HOCl (aq)+ H₂O (l)--> <-- H₃O + (aq) + OCl^- (aq)

A)7.2 × 10^-4 M

B)1.9 × 10^-4 M

C)7.2 × 10^-5 M

D)2.8 × 10^-5 M

Answer C

A 1.0 L buffer solution is 0.250 M HC₂H₃O₂ and 0.050 M LiC₂H₃O₂. Which of the following actions will destroy the buffer?

A)adding 0.050 moles of LiC₂H₃O₂

B)adding 0.050 moles of HC₂H₃O₂

C)adding 0.050 moles of NaOH

D)adding 0.050 moles of HCl

E)None of the above will destroy the buffer.

Answer D

Identify the weak diprotic acid.

A)HCOOH

B)CH₃COOH

C)H₂CO₃

D)H₃PO₄

E)H₂SO₄

Answer C

Determine the K_a of an acid whose 0.294 M solution has a pH of 2.80.

A)5.4 × 10^-3

B)8.5 × 10^-6

C)1.2 × 10^-5

D)4.9 × 10^-7

E)2.7

Answer B

Identify the weakest acid.

A)HF

B)HI

C)HCl

D)HBr

E)not enough information is available

Answer A

Calculate the molarity of hydroxide ion in an aqueous solution that has a pOH of 5.00.

A)9.0 × 10^-14

B)5.0 × 10^-14

C)9.00

D)1.0 × 10^-9

E)1.0 × 10^-5

Answer E

Calculate the pH of a buffer that is 0.040 M HF and 0.020 M LiF. The K_a for HF is 3.5 × 10^-4.

A)3.16

B)3.76

C)4.86

D)2.06

E)3.46

Answer A

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.

A)2.11

B)1.22

C)1.00

D)1.40

E)1.30

Answer D

Identify the weak diprotic acid.

A)H₃PO₄

B)HClO₄

C)H₂SO₃

D)H₂SO₄

E)HNO₃

Answer C

You wish to prepare an HC₂H₃O₂ buffer with a pH of 4.24. If the pK_a of is 4.74, what ratio of C₂H₃O₂ ^-/HC₂H₃O₂ must you use?

A)0.32

B)2.8

C)0.10

D)0.50

E)2.0

Answer A

A 7.0 × 10^-3 M aqueous solution of Ca(OH)₂ at 25.0°C has a pH of ________.

A)1.85

B)12.15

C)11.85

D)1.4 × 10^-2

E)7.1 × 10^-13

Answer B

A 100.0 mL sample of 0.180 M HClO₄ is titrated with 0.270 M LiOH. Determine the pH of the solution after the addition of 75.0 mL of LiOH.

A)2.65

B)1.89

C)12.1

D)13.06

E)11.35

Answer C

Calculate the pH for an aqueous solution of pyridine that contains 2.15 x 10^-4 M hydroxide ion.

A)3.67

B)2.15 × 10^-4

C)10.33

D)4.65 × 10^-11

Answer C

Determine the molar solubility of BaF₂ in a solution containing 0.0750 M LiF. K_sp (BaF₂) = 1.7 × 10^-6.

A)8.5 × 10^-7 M

B)3.0 × 10^-4 M

C)1.2 × 10^-2 M

D)2.3 × 10^-5 M

E)0.0750 M

Answer B

Determine the pOH of a 0.00598 M HClO₄ solution.

A)11.777

B)2.223

C)6.434

D)7.566

E)3.558

Answer A

A 100.0 mL sample of 0.20 M HF is titrated with 0.10 M KOH. Determine the pH of the solution after the addition of 200.0 mL of KOH. The K_a of HF is 3.5 × 10^-4.

A)9.62

B)7.00

C)3.46

D)10.54

E)8.14

Answer E

The molar solubility of Ag₂S is 1.26 × 10^-16 M in pure water. Calculate the K_sp for Ag₂S.

A)6.81 × 10^-63

B)3.78 × 10^-12

C)8.00 × 10^-48

D)1.12 × 10^-8

E)1.59 × 10^-32

Answer C

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.

A)7.06

B)6.46

C)5.99

D)8.01

E)7.54

Answer D

A 100.0 mL sample of 0.18 M HClO₄ is titrated with 0.27 M LiOH. Determine the pH of the solution after the addition of 66.67 mL of LiOH (this is the equivalence point).

A)7.00

B)2.76

C)11.24

D)13.03

E)0.97

Answer A

Calculate the pH of a buffer that is 0.225 M HC₂H₃O₂ and 0.162 M KC₂H₃O₂. The K_a for HC₂H₃O₂ is 1.8 × 10^-5.

A)4.74

B)4.89

C)9.26

D)9.11

E)4.60

Answer E

What is the hydronium ion concentration of a 0.500 M acetic acid solution with K _a = 1.8 × 10^-5? The equation for the dissociation of acetic acid is:

CH₃CO₂H(aq)+H₂O (l) <-- ---> H₃O⁺(aq)+ CH₃CO₂ ^-(aq)

A)3.0 × 10^-2 M

B)3.0 × 10^-3 M

C)4.2 × 10^-3 M

D)4.2 × 10^-2 M

Answer B

Calculate the hydronium ion concentration in an aqueous solution that contains 2.50 × 10^-6 M in hydroxide ion.

A)4.00 × 10^-7 M

B)4.00 × 10^-8 M

C)4.00 × 10^-9 M

D)5.00 × 10^-9 M

Answer C