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Chem II > ch 17 > Flashcards

ch 17 Flashcards

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1
Q

If 25 mL of 0.750 M HCl are added to 100. mL of 0.302 M NaOH, what is the final pH?

A

a

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2
Q

Calculate the pH of a solution made by mixing 100.0 mL of 0.627 M NH3 with 100.0 mL of 0.100 M HCl. (Kb for NH3 = 1.8 × 10–5)

A

a

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3
Q

What is the pH of a buffer that results when 0.50 mole of H3PO4 is mixed with 0.75 mole of NaOH and diluted with water to 1.00 L? (The acid dissociation constants of phosphoric acid are Ka1 = 7.5 × 10–3, Ka2 = 6.2 × 10–8, and Ka3 = 3.6 × 10–13)

A

d

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4
Q

You have 75.0 mL of 0.17 M HA. After adding 30.0 mL of 0.10 M NaOH, the pH is 5.50. What is the Ka value of HA?

A

b.

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5
Q

Two important biological buffer systems control pH in the range of 6.9 to 7.4. These buffer systems are H2CO3/HCO3– and _____.

A

H2PO4-/HPO4^2-

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6
Q

What molar ratio of acetic acid to sodium acetate is required to create a buffer solution having a pH of 4.88 at 25°C? Ka for HC2H3O2 is 1.8 × 10–5.

A

a.

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7
Q

For a monoprotic acid titration, the _____ in a titration is the point where number of moles of a strong base added equals the number of moles of an acid initially present.

A

equivalence point

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8
Q

A 1.0 liter solution contains 0.25 M hydrogen fluoride (HF) and 0.38 M sodium fluoride (NaF). What is the pH of this solution? (Ka for HF is 7.2 × 10–4)

A

b.

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9
Q

If the ratio of acid to base in a buffer is increased by a factor of 10, the buffer pH decreases by ________.

A

1

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10
Q

What will be the pH of the solution when 0.10 mol of H+ ion is added to a 2.0 liter buffered solution composed of 0.45 M ammonia, NH3, and 0.26 M ammonium fluoride, NH4F? (Kb for ammonia = 1.8 × 10–5)

A

c.

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11
Q

A 50.0 mL sample of 0.155 M HNO2(aq) is titrated with 0.100 M NaOH(aq). What is the pH of a solution after the addition of 25.0 mL of NaOH? (Ka of HNO2 = 4.5 × 10–4)

A

a.

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12
Q

How many moles of HCl must be added to 1.0 L of 1.0 M NH3(aq) to make a buffer with a pH of 9.00? (pKa of NH4+ = 9.25)

A

d.

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13
Q

Which acid-base combination is depicted by this titration curve? The dot on the curve is located at the titrant volume where the titration solution pH equals 7.

A

a.

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14
Q

A certain weak base B has a base-ionization constant Kb of 5.9 × 10–4 at 25°C. If strong acid is added to a solution of B, at what pH will [B] = [BH+]?

A

b.

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15
Q

A 50.00-mL solution of 0.0350 M ethylamine (Kb = 5.6 × 10–4) is titrated with a 0.0135 M solution of hydrochloric acid as the titrant. What is the pH at the equivalence point? (Kw = 1.0 × 10–14)

A

b.

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16
Q

What is the solubility product expression for La(OH)3?

A

c.

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17
Q

Which of the following conditions is/are met at the equivalence point of the titration of a monoprotic weak base with a strong acid?

A

d.

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18
Q

If 25 mL of 0.10 M NaOH is added to 40 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

not c. or b.

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19
Q

A solution containing 10. mmol of CO32− and 5.0 mmol of HCO3−is titrated with 1.1 M HCl. What total volume of HCl must be added to reach the second equivalence point? (1 mmol = 0.001 mol)

A

d.

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20
Q

What mass of solid NaCH3CO2 (molar mass = 82.0 g/mol) should be added to 1.0 L of 0.50 M CH3CO2H to make a buffer with a pH of 7.21? (pKa of CH3CO2H = 7.21)

A

c,

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21
Q

What is the effect of adding an aqueous sodium hydroxide solution to an aqueous solution of ammonia?

A

e.

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22
Q

Which of the following combinations would be best to buffer an aqueous solution at a pH of 9.24?

A

e.

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23
Q

A volume of 25.0 mL of 0.100 M C6H5CO2H(aq) is titrated with 0.100 M NaOH(aq). What is the pH after the addition of 12.5 mL of NaOH? (Ka of benzoic acid = 6.3 × 10–5)

A

b.

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24
Q

When a weak base is titrated with a strong acid, the pH at the equivalence point is _____.

A

a.

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25
Q

When mixed in appropriate amounts, each of the following mixtures can produce an effective buffer solution except _____.

A

e.

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26
Q

What color change is exhibited by phenolphthalein during a titration of aqueous acetic acid with aqueous sodium hydroxide?

A

a.

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27
Q

The solubility of strontium carbonate (SrCO3) in water at 25°C is g/L. What is the Ksp of this sparingly soluble salt?

A

a.

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28
Q

A buffer is composed of 0.400 mol H2PO4– and 0.400 mol HPO42– diluted with water to a volume of 1.00 L. The pH of the buffer is 7.210. How many moles of HCl must be added to decrease the pH to 6.210?

A

c

29
Q

The pH of a solution at the equivalence point in a monoprotic strong acid-−strong base reaction is always 7.0 at 25 °C. Is this statement true or false?

A

true

30
Q

What is the pH of a buffer that results when 0.40 mol NaHCO2 is mixed with 100.0 mL of 2.00 M HCl(aq) and diluted with water to 250 mL? (Ka of HCO2H = 1.8 × 10–4)

A

d.

31
Q

A 1.0-liter solution contains 0.25 M HF and 0.33 M NaF (Ka for HF is 7.2 × 10–4).
If one adds 0.30 liters of 0.020 M KOH to the solution, what will be the change in pH?

A

a.

32
Q

Hyperventilation can cause your blood pH to rise. One way to lower your blood pH is to breathe into a paper bag, thus recycling the air you exhale. Why does this procedure lower your blood pH?

A

idk

33
Q

What is the pH of a buffer that results when 0.50 mole of H3PO4 is mixed with 0.25 mole of NaOH and diluted with water to 1.00 L? (The acid dissociation constants of phosphoric acid are Ka1 = 7.5 × 10–3, Ka2 = 6.2 × 10–8, and Ka3 = 3.6 × 10–13)

A

b.

34
Q

The concentration of Pb2+ in an aqueous solution is 5.5 × 10–3 M. What concentration of SO42– is required to begin precipitating PbSO4? The Ksp of PbSO4 is 2.5 × 10–8.

A

b.

35
Q

An impure sample of sodium carbonate, Na2CO3, is titrated with 0.113 M HCl according to the reaction below.
2 HCl(aq) + Na2CO3(aq) CO2(g) + H2O() + 2 NaCl(aq)
What is the percent of Na2CO3 in a 0.613 g sample if the titration requires 26.14 mL of HCl? The molar mass of Na2CO3 is 106.0 g/mol.

A

c

36
Q

What is the pH of a buffer composed of 0.35 M H2PO4–(aq) and 0.65 M HPO42–(aq)? (Ka of H2PO4– is 6.2 × 10–8)

A

c.

37
Q

How many moles of solid NaF would have to be added to 1.0 L of 1.85 M HF solution to achieve a buffer of pH 3.35? Assume there is no volume change. (Ka for HF = 7.2 × 10–4)

A

a.

38
Q

How many moles of solid NaF would have to be added to 1.0 L of 2.16 M HF solution to achieve a buffer of pH 3.35? Assume there is no volume change. (Ka for HF = 7.2 × 10–4)

A

a.

39
Q

A 50.00-mL solution of 0.0400 M hydrofluoric acid (Ka = 7.2 × 10–4) is titrated with a 0.0153 M solution of NaOH as the titrant. What is the pH of at the equivalence point? (Kw = 1.00 × 10–14)

A

a.

40
Q

Titration of 0.1615 g of an unknown monoprotic acid dissolved in 25.00 mL of water requires 21.84 mL of 0.1231 M NaOH to reach the endpoint. What is the molar mass of the acid?

A

a.

41
Q

Consider the titration of 300.0 mL of 0.414 M NH3 (Kb = 1.8 ×10–5) with 0.500 M HNO3. After 150.0 mL HNO3 has been added, what is the pH of the solution?

A

b

42
Q

An acid-base equilibrium system is created by dissolving 0.50 mol CH3CO2H in water to a volume of 1.0 L. What is the effect of adding 0.50 mol CH3CO2–(aq) to this solution?

A

c.

43
Q

A solution containing 10. mmol of CO32−and 5.0 mmol of HCO3−is titrated with 1.1 M HCl. What volume of HCl must be added to reach the first equivalence point? (1 mmol = 0.001 mol)

A

c.

44
Q

Which is the best colored indicator to use in the titration of 0.1 M CH3CO2H(aq) with NaOH(aq)? Why? (Ka of CH3CO2H = 1.8 × 10–5, Kb of CH3CO2– = 5.6 × 10–10)

A

not d. or a or b.

45
Q

All of the following statements concerning acid-base buffers are true EXCEPT

A

not c.

46
Q

A 25.00-mL sample of propionic acid, HC3H5O2, of unknown concentration was titrated with 0.145 M KOH. The equivalence point was reached when 43.02 mL of base had been added. What was the original concentration of the propionic acid?

A

e.

47
Q
A
48
Q

If 0.50 L of a buffer containing 1.0 mol H2PO4− and 1.0 mol HPO42− is diluted to a volume of 5.0 L, the pH

A

e.

49
Q

What mass of sodium hydroxide must be added to 65.0 mL of 0.926 M acetic acid in order to create a buffer with a pH of 4.83? Ka for acetic acid is 1.8 × 10–5.

A

b

50
Q

If 20 mL of 0.10 M NaOH is added to 40 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

e.

51
Q

The solubility of manganese(II) carbonate is 5.4 × 10–4 g/L. What is the solubility product constant for manganese(II) carbonate?

A

a.

52
Q

The concentration of calcium carbonate in a saturated aqueous solution at 25°C is M. What is the Ksp of this sparingly soluble salt?

A

a.

53
Q

What is the pH of a solution made by combining 134 mL of 0.26 M NaC2H3O2 with 211 mL of 0.31 M HC2H3O2? The Ka of acetic acid is 1.75 × 10-5.

A

not d. or e.

54
Q

A 25.0 mL sample of 0.10 M sodium benzoate is titrated with 0.10 M HCl(aq). What is the pH after the addition of 32.0 mL of HCl(aq)? (Kb of C6H5CO2– = 1.6 × 10–10)

A

c.

55
Q

Which of the following indicators is most suitable for the titration of a 25.00-mL sample of 0.140 M propionic acid, HC3H5O2, with strong base?

A

d.

56
Q

If the ratio of acid to base in a buffer increases by a factor of 10, the pH of the buffer

A

b.

57
Q

What is the pH of the buffer that results when 32 g sodium acetate (NaCH3CO2) is mixed with 500.0 mL of 1.0 M acetic acid (CH3CO2H) and diluted with water to 1.0 L? (Ka of CH3CO2H = 1.8 × 10–5)

A

d.

58
Q

What is the pH of an aqueous solution composed of 0.64 M NH4+ and 0.20 M NH3? (Ka of NH4+ = 5.6 × 10–10)

A

not d or a.

59
Q

The Ksp of Ca(OH)2 is 5.5 × 10–5 at 25 °C. What is the concentration of OH–(aq) in a saturated solution of Ca(OH)2(aq)?

A

e.

60
Q

What is the pH of a solution that is 0.044 M in HA and also 0.0044 M in NaA? (Ka = 4.7 × 10–6)

A

b.

61
Q

What is the pH at the equivalence point when a 25.0 mL sample of 0.200 M aqueous formic acid (HCO2H) is titrated with 0.100 M aqueous potassium hydroxide? (Ka of HCO2H = 1.8 × 10–4)

A

c.

62
Q

Which of the following is the common name for iron(II) carbonate?

A

not d. or b.

63
Q

What is the maximum hydroxide-ion concentration that a 0.019 M MgCl2 solution could have without causing the precipitation of Mg(OH)2? For Mg(OH)2, Ksp = 1.8 × 10–11.

A

not b. or c.

64
Q

To make a buffer with a pH of 8.00, you should use a weak acid with a Ka close to _______.

A

1?

65
Q

Potassium hydrogen phthalate (KHP) is used to standardize sodium hydroxide. If 35.39 mL of NaOH(aq) is required to titrate 0.8246 g KHP to the equivalence point, what is the concentration of the NaOH(aq)? (The molar mass of KHP = 204.2 g/mol)

A

not b. or c. or a.

66
Q

A buffer contains 0.50 mol NH4+ and 0.50 mol NH3 diluted with water to 1.0 L. How many moles of NaOH are required to increase the pH of the buffer to 10.00? (pKa of NH4+ = 9.25)

A

c.

67
Q

What is the pH of the buffer that results when 12.0 g of NaH2PO4 and 8.00 g of Na2HPO4 are diluted with water to a volume of 0.50 L? (Ka of H2PO4– = 6.2 × 10–8, the molar masses of NaH2PO4 and Na2HPO4 are 120.0 g/mol and 142.0 mol, respectively)

A

not c. or b. or d.

68
Q

A 50.00-mL solution of 0.0426 M trimethylamine (Kb = 6.5 × 10–5) is titrated with a 0.0257 M solution of hydrochloric acid as the titrant. What is the pH of the base solution after 22.31 mL of titrant have been added? (Kw = 1.00 × 10–14)

A

b

69
Q

Which of the following mathematical expressions is the Henderson–Hasselbalch equation?

A

not c. maybe e or b.

Chem II (13 decks)

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