chem ch. 15-18 exam 2

Determine the molar solubility of PbSO4 in pure water. Ksp (PbSO4) = 1.82 × 10-8. A) 1.82 × 10-8 M B) 1.35 × 10-4 M C) 9.1 × 10-9 M D) 3.31 × 10-16 M E) 4.48 × 10-4 M

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

Place the following in order of increasing acid strength. HBrO2 HBrO3 HBrO HBrO4 A) HBrO2 < HBrO4 < HBrO < HBrO3 B) HBrO < HBrO2 < HBrO3 < HBrO4 C) HBrO2 < HBrO3 < HBrO4 < HBrO D) HBrO4 < HBrO2 < HBrO3 < HBrO E) HBrO < HBrO4 < HBrO3 < HBrO2

B

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

What is the concentration of hydroxide ions in pure water at 30.0∘C, if Kw at this temperature is 1.47 × 10-14? A) 1.00 × 10-7 M B) 1.30 × 10-7 M C) 1.47 × 10-7 M D) 8.93 × 10-8 M E) 1.21 × 10-7 M

E

Calculate the hydronium ion concentration in an aqueous solution with a pOH of 4.33 at 25°C. A) 2.1 × 10-10 M B) 9.7 × 10-10 M C) 4.7 × 10-5 M D) 3.8 × 10-5 M E) 6.3 × 10-6 M

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

What is the conjugate base of H2PO4− ? A) HPO42- B) PO43- C) H3PO4 D) H3O+ E) OH−

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 is an Arrhenius acid? A) H2SO4 B) LiOH C) NH2CH3 D) CH3CCl3 E) More than one of these is an Arrhenius acid.

A

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 would have the highest pH? Assume that they are all 0.10 M in acid at 25∘C. The acid is followed by its Ka value. A) HF, 3.5 × 10-4 B) HCN, 4.9 × 10-10 C) HNO2, 4.6 × 10-4 D) HCHO2, 1.8 × 10-4 E) HClO2, 1.1 × 10-2

B

Determine the pH of a 0.023 M HNO3 solution. A) 12.36 B) 3.68 C) 1.64 D) 2.30 E) 2.49

C

The stronger the acid, then which of the following is TRUE? A) The stronger the conjugate acid. B) The stronger the conjugate base. C) The weaker the conjugate base. D) The weaker the conjugate acid. E) None of the above.

C

Which of the following is a Br∅nsted-Lowry base? A) CBr4 B) HCN C) NH3 D) Cl2 E) None of the above are Br∅nsted-Lowry bases.

C

A solution is prepared by dissolving 0.23 mol of hydrazoic acid and 0.27 mol of sodium azide 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 hydrazoic acid is 1.9 × 10-5. A) H2O B) H3O+ C) azide D) hydrazoic 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)[BaF2]/[ba2+][F-]2 B)[Ba2+][F-]2/[BaF2] C) [Ba2+]2[ F−] D) [Ba2+][F−]2 E) [Ba2+][2F−]

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

When titrating a strong monoprotic acid and 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

Which of the following species is amphoteric? A) CO32- B) HF C) NH4+ D) HPO42- E) None of the above are amphoteric.

D