ch 17 chem

A sample contains Ba3(PO4)2, CdS, AgCl, NH4Cl, and ZnS. Identify the precipitate after the addition of 6 M HCl, then H2S and 0.2 M HCl. A) Ba3(PO4)2 B) CuS C) AgCl D) NH4Cl E) CoS

B

Give the equation for an unsaturated solution in comparing Q with Ksp. A) Q > Ksp B) Q < Ksp C) Q = Ksp D) Q ≠ Ksp E) none of the above

B

Identify the compound that is acid-insoluble. A) PbCl2 B) As2S3 C) FeS D) Ca3(PO4)2 E) LiCl

B

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? 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

A sample contains Ba3(PO4)2, CdS, AgCl, NH4Cl, and ZnS. Identify the precipitate after the addition of 6 M HCl; H2S and 0.2 M HCl; OH- to a pH of 8; and (NH4)2HPO4 with NH3. A) Ba3(PO4)2 B) PbS C) AgCl D) NH4Cl E) CoS

A

Animals will lick up ethylene glycol (antifreeze) due to its sweet taste. The antidote for ethylene glycol poisoning is the administration of A) ethyl alcohol ( alcoholic drinks). B) isopropyl alcohol (rubbing alcohol). C) mineral oil (laxative). D) vinegar. E) sodium bicarbonate (baking soda).

A

Define buffer capacity. A) Buffer capacity is the amount of acid or base that can be added to a buffer without destroying its effectiveness. B) Buffer capacity is the amount of acid that can be added until all of the base is used up. C) Buffer capacity is the amount of base that can be added until all of the acid is used up. D) Buffer capacity is the amount of acid that can be added until all of the acid is used up. E) Buffer capacity is the amount of base that can be added until all of the base is used up.

A

Describe the solubility of Al(OH)3 with respect to pH. A) soluble at low pH, insoluble in pH-neutral solution, and soluble at high pH B) soluble at low pH, insoluble in pH-neutral solution, and insoluble at high pH C) insoluble at low pH,insoluble in pH-neutral solution, and soluble at high pH D) soluble at low pH, in pH-neutral solution, and at high pH E) pH has no effect on the solubility.

A

Give the expression for the solubility product constant for Cr2(CO3)3. A) [Cr3+]2[CO32-]3 B) C) D) E) [3Cr3+]3[2CO32-]2

A

Gives what happens at low pH for aluminum hydroxide. A) Al(H2O)63+ dissolves B) Al(H2O)2(OH)4- precipitates C) Al(OH)6 dissolves D) Al precipitates E) Al dissolves

A

If the pKa of HCHO2 is 3.74 and the pH of an HCHO2/NaCHO2 solution is 3.89, 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

A

Which of the following compounds solubility will not be affected by a low pH in solution? A) AgCl B) Ca(OH)2 C) SrF2 D) CuS E) CaCO3

A

Which of the following is TRUE? A) The equivalence point is where the amount of acid equals the amount of base during any acid-base titration. B) At the equivalence point, the pH is always 7. C) An indicator is not pH sensitive. D) A titration curve is a plot of pH vs. the [base]/[acid] ratio. E) None of the above are true.

A

Which of the following solutions is a good buffer system? A) a solution that is 0.10 M HC2H3O2 and 0.10 M LiC2H3O2 B) a solution that is 0.10 M HBr and 0.10 M LiC2H3O2 C) a solution that is 0.10 M HI and 0.10 M NH4+ D) a solution that is 0.10 M LiOH and 0.10 M KOH E) None of the above are buffer systems.

A

Gives what happens at high pH for aluminum hydroxide. A) Al(H2O)43+ dissolves B) Al(H2O)2(OH)4- dissolves C) Al(OH)6 dissolves D) Al precipitates E) Al dissolves

B

Identify the indicator that has two endpoints. A) phenol red B) alizarin C) m-nitrophenol D) phenolphthalein E) alizarin yellow R

B

If a chemist wishes to prepare a buffer that will be effective at a pH of 3.00 at 25°C, the best choice would be an acid component with a Ka equal to A) 9.10 × 10-2. B) 9.10 × 10-4. C) 9.10 × 10-6. D) 9.10 × 10-8. E) 9.10 × 10-10.

B

If the pKa of HCHO2 is 3.74 and the pH of an HCHO2/NaCHO2 solution is 3.74, 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.

B

Which of the following compounds will be more soluble in acidic solution than in pure water? A) PbI2 B) CuS C) Ca(ClO4)2 D) CuCl E) None of the above will be more soluble in acidic solution.

B

Which of the following compounds will have the highest molar solubility in pure water? A) PbSO4, Ksp = 1.82 × 10-8 B) MgCO3, Ksp = 6.82 × 10-6 C) AgCl, Ksp = 1.77 × 10-10 D) PbS, Ksp = 9.04 × 10-29 E) HgS, Ksp = 1.60 × 10-54

B

Which of the following is 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.

B

Which of the following solutions is a good buffer system? A) a solution that is 0.10 M NaCl and 0.10 M HCl B) a solution that is 0.10 M HCN and 0.10 M LiCN C) a solution that is 0.10 M NaOH and 0.10 M HNO3 D) a solution that is 0.10 M HNO3 and 0.10 M NaNO3 E) a solution that is 0.10 M HCN and 0.10 M K Br

B

A 1.0 L buffer solution is 0.250 M HC2H3O2 and 0.050 M NaC2H3O2. Which of the following actions will destroy the buffer? A) adding 0.050 moles of NaC2H3O2 B) adding 0.050 moles of HC2H3O2 C) adding 0.050 moles of HCl D) adding 0.050 moles of NaOH E) None of the above will destroy the buffer

C

A sample contains Ba3(PO4)2, CdS, AgCl, NH4Cl, and ZnS. Identify the precipitate after the addition of 6 M HCl. A) Ba3(PO4)2 B) CuS C) AgCl D) NH4Cl E) NiS

C

A solution is prepared by dissolving 0.23 mol of butanoic acid and 0.27 mol of sodium butanoate in water sufficient to yield 1.00 L of solution. The addition of 0.05 mol of HCl to this buffer solution causes the pH to drop slightly. The pH does not decrease drastically because the HCl reacts with the ________ present in the buffer solution. The Ka of butanoic acid is 1.36 × 10-3. A) H2O B) H3O+ C) butanoate ion D) butanoic acid E) This is a buffer solution: the pH does not change upon addition of acid or base.

C

An important buffer in the blood is a mixture of A) sodium chloride and hydrochloric acid. B) hydrochloric acid and sodium hydroxide. C) carbonic acid and bicarbonate ion. D) acetic acid and bicarbonate ion. E) acetic acid and carbonate ion.

C

Give the equation for a saturated solution in comparing Q with Ksp. A) Q > Ksp B) Q < Ksp C) Q = Ksp D) Q ≠ Ksp E) none of the above

C

Give the expression for the solubility product constant for PbCl2. A) B) C) [Pb2+][Cl⁻]2 D) E) [Pb2+]2[ Cl⁻]

C

Gives what happens at neutral pH for aluminum hydroxide. A) Al(H2O)53+ precipitates B) Al(H2O)4(OH)2- dissolves C) Al(OH)3 precipitates D) Al precipitates E) Al dissolves

C

Identify the compound that is base-insoluble. A) PbCl2 B) Sb2S3 C) NiS D) Ca3(PO4)2 E) KCl

C

Identify the indicator that can be used at the lowest pH. A) 2,4-dinitrophenol B) thymol blue C) crystal violet D) thymolphthalein E) methyl red

C

Identify the pH of normal blood. A) 6.9 B) 7.1 C) 7.4 D) 7.6 E) 7.9

C

The highest pH for an effective buffer occurs when the base is how many times as concentrated as the acid? A) 4 B) 5 C) 10 D) 15 E) 40

C

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

C

Which of the following compounds will have the highest molar solubility in pure water? A) SnS, Ksp = 1.0 × 10-26 B) CuS, Ksp = 1.27 × 10-36 C) Fe(OH)3, Ksp = 2.79 × 10-39 D) ZnS, Ksp = 2.0 × 10-25 E) Ag2S, Ksp = 6.0 × 10-51

C

Which of the following would be considered a complex ion? A) F- B) PO33- C) AlF6- D) Fe2+ E) NH4+

C

Which one of the following statements is TRUE? A) A buffer is an aqueous solution composed of two strong bases. B) A buffer can absorb an unlimited amount of base. C) A buffer resists pH change by neutralizing added acids and bases. D) A buffer does not change pH when strong base is added. E) All of the above are true.

C

A ligand is a molecule or ion that acts as a A) Lewis acid B) Brønsted-Lowry acid C) Arrhenius base D) Lewis base E) conjugate base

D

A sample contains Ba3(PO4)2, CdS, AgCl, NH4Cl, and ZnS. Identify the soluble ions after the addition of 6 M HCl; H2S and 0.2 M HCl; OH- to a pH of 8; and (NH4)2HPO4 with NH3. A) Ba3(PO4)2 B) CdS C) AgCl D) NH4Cl E) FeS

D

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. 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.

D

Give the expression for the solubility product constant for BaF2. A) B) C) [Ba2+]2[ F⁻] D) [Ba2+][F⁻]2 E) [Ba2+][ F⁻]

D

Identify the most common indicator. A) alizarin B) bromophenol blue C) phenol red D) phenolphthalein E) thymolphthalein

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.

D

Stalactites and stalagmites form as ________ precipitates out of the water evaporating in underground caves. A) hydrochloric acid B) sodium hydroxide C) sodium chloride D) calcium carbonate E) sodium bicarbonate

D

When titrating a strong monoprotic acid with KOH at 25°C, the A) pH will be less than 7 at the equivalence point. B) pH will be greater than 7 at the equivalence point. C) titration will require more moles of base than acid to reach the equivalence point. D) pH will be equal to 7 at the equivalence point. E) titration will require more moles of acid than base to reach the equivalence point.

D

A sample contains Ba3(PO4)2, CdS, AgCl, NH4Cl, and ZnS. Identify the precipitate after the addition of 6 M HCl; H2S and 0.2 M HCl; and OH- to a pH of 8. A) Ba3(PO4)2 B) CdS C) AgCl D) NH4Cl E) FeS

E

Give the expression for the solubility product constant for Ca3(PO4)2. A) B) C) D) [ Ca2+]2[ PO43-]3 E) [Ca2+]3[PO43-]2

E

Identify a good buffer. A) small amounts of both a weak acid and its conjugate base B) significant amounts of both a strong acid and a strong base C) small amounts of both a strong acid and a strong base D) significant amounts of both a weak acid and a strong acid E) significant amounts of both a weak acid and its conjugate base

E

Identify the indicator that can be used at the highest pH. A) alizarin B) thymol blue C) methyl red D) thymolphthalein E) alizarin yellow R

E

When titrating a monoprotic strong acid with a weak base at 25°C, the A) pH will be 7 at the equivalence point. B) pH will be greater than 7 at the equivalence point. C) titration will require more moles of the base than acid to reach the equivalence point. D) titration will require more moles of acid than base to reach the equivalence point. E) pH will be less than 7 at the equivalence point.

E