HW06 - Buffers, Titrations, and Polyprotics

Question 11.0 pts

When an acid and base neutralize each other, the products are generally water and...
  1. a gel.
  2. a colloid.
  3. an ion.
  4. a salt.

Question 21.0 pts

How many moles of Ca(OH)2 are needed to neutralize three moles of HCl?
  1. 1.5
  2. 3
  3. 2
  4. 1

Question 31.0 pts

An aqueous solution is prepared with 2 moles of HCl and 1 mole of Ca(OH)2. The resulting solution contains mainly...
  1. water, Cl- ions, and Ca2+ ions.
  2. water, Cl- ions, H+ ions, OH- ions, and Ca2+ ions.
  3. water, Cl- ions, OH- ions, and Ca2+ ions.
  4. water, Cl- ions, H+ ions, and Ca2+ ions.

Question 41.0 pts

Identify the products of the following chemical reaction:

3LiOH + H3PO4 \longrightarrow

  1. 3H+ + 3O2 + H3Li3
  2. Li3P + 2H2O + H3O5
  3. 3LiH + (OH)3PO4
  4. Li3PO4 + 3H2O

Question 51.0 pts

Identify the products of the following chemical reaction:

Sr(OH)2 + 2HNO3 \longrightarrow

  1. SrH2 + HNO5
  2. SrNO3 + H2O
  3. Sr(NO2)2 + 2H2O2
  4. Sr(NO3)2 + 2H2O

Question 61.0 pts

Aqueous ammonia can be used to neutralize sulfuric acid and nitric acid to produce two salts extensively used as fertilizers. They are...
  1. cyanamide and cellulose nitrate, respectively
  2. NH4SO4 and NH4NO3, respectively
  3. NH4SO3 and NH4OH, respetively
  4. (NH4)2SO4 and NH4NO3, respectively

Question 71.0 pts

Identify the salt that is produced from the acid-base neutralization reaction between potassium hydroxide and acetic acid.
  1. potassium cyanide
  2. potassium amide
  3. potassium formate
  4. potassium acetate

Question 81.0 pts

What is the pH of an aqueous solution that is 0.018 M C6H5NH2 (Kb = 4.3x10-10) and 0.12 M C6H5NH3Cl?
  1. 3.81
  2. 4.02
  3. 4.63
  4. 2.87

Question 91.0 pts

A buffer solution is made by dissolving 0.45 moles of a weak acid (HA) and 0.33 moles of KOH into 710 mL of solution. What is the pH of this buffer? Ka = 6x10-6 for HA.
  1. 5.22
  2. 8.34
  3. 13.23
  4. 5.66

Question 101.0 pts

Which one of the following combinations is NOT a buffer solution?
  1. HBr and KBr
  2. HCN and NaCN
  3. CH3COOH and NaCH3COO
  4. NH3 and (NH4)2SO4

Question 111.0 pts

Which of the following mixtures will be a buffer when dissolved in a liter of water?
  1. 0.2 mol HBr and 0.1 mol NaOH
  2. 0.3 mol NaCl and 0.3 mol HCl
  3. 0.2 mol HF and 0.1 mol NaOH
  4. 0.1 mol Ca(OH)2 and 0.3 mol HI

Question 121.0 pts

What is the pH of a solution which is 0.600 M in dimethylamine ((CH3)2NH) and 0.400 M in dimethylamine hydrochloride ((CH3)2NH2Cl)? Kb for dimethylamine = 7.4x10-4.
  1. 11.21
  2. 10.78
  3. 11.05
  4. 10.87

Question 131.0 pts

What would be the final pH if 0.0100 moles of solid NaOH were added to 100mL of a buffer solution containing 0.600 molar formic acid (ionization constant = 1.8x10-4) and 0.300 M sodium formate?
  1. 3.65
  2. 3.44
  3. 4.05
  4. 3.84

Question 141.0 pts

A buffer was prepared by mixing 0.200 moles of ammonia (Kb = 1.8x10-5) and 0.200 moles of ammonium chloride to form an aqueous solution with a total volume of 500 mL. 250 mL of the buffer was added to 50.0 mL of 1.00 M HCl. What is the pH of this second solution?
  1. 8.38
  2. 8.53
  3. 8.18
  4. 8.78

Question 151.0 pts

A solution is 0.30 M in NH3. What concentration of NH4Cl would be required to achieve a buffer solution with a final pH of 9.0? Kb = 1.8x10-5 for NH3.
  1. 0.32 M
  2. 0.54 M
  3. 0.10 M
  4. 0.45 M

Question 161.0 pts

What is the pH at the half-stoichiometric point for the titration of 0.22 M HNO2(aq) with 0.1 M KOH(aq)? For HNO2, Ka = 4.3x10-4.
  1. 2.31
  2. 7.00
  3. 2.01
  4. 3.37

Question 171.0 pts

For the titration of 50.0 mL of 0.020 M aqueous salicylic acid with 0.020 M KOH (aq), calculate the pH after the addition of 55.0 mL of the base. For salicylic acid, pKa = 2.97.
  1. 10.98
  2. 11.26
  3. 7.00
  4. 11.02

Question 181.0 pts

Consider the titration of 50.0 mL of 0.0200 M HClO(aq) with 0.100 M NaOH(aq). What is the formula of the main species in the solution after the addition of 10.0 mL of base?
  1. HClO
  2. ClO-
  3. ClO2
  4. NaOH

Question 191.0 pts

50.0 mL of 0.0018 M aniline (a weak base) is titrated with 0.0048 M HNO3. How many mL of the acid are required to reach the equivalence point?
  1. 133 mL
  2. This is a bad titration as HNO3 is not a strong acid.
  3. 18.8 mL
  4. 4.21 mL

Question 201.0 pts

When we titrate a weak base with a strong acid, the pH at the equivalence point will be...
  1. It is impossible to know unless we are given the Kb of the weak base.
  2. pH = 0
  3. pH > 7
  4. pH < 7

Question 211.0 pts

What is the pH at the equivalence point in the titration of 10.0 mL of 0.35 M unknown acid HZ with 0.200 M NaOH? Ka = 2.4x10-7 for the unknown acid HZ
  1. 9.86
  2. 10.1
  3. 7.00
  4. 4.14

Question 221.0 pts

What is the pH at the equivalence point of the titration pictures below?

titration weak acid.png

  1. 7.0
  2. 9.2
  3. 3.4
  4. 1.8
  5. 5.5

Question 231.0 pts

Look at the titration diagram in the question above. What type of titration is occurring?
  1. a strong base titrated with a weak acid
  2. a weak base titrated with a strong acid
  3. a strong base titrated with a strong acid
  4. a weak base titrated with a weak acid

Question 241.0 pts

The acid form of an indicator is yellow and its anion is blue. The Ka of this indicator is 10-5. What will be the approximate pH range over which this indicator changes color?
  1. 5 < pH < 7
  2. 6 < pH < 8
  3. 4 < pH < 6
  4. 3 < pH < 5

Question 251.0 pts

The unionized form of an acid indicator is yellow and its anion is blue. The Ka of this indicator is 10-5. What will be the color of the indicator in a solution of pH 3?
  1. orange
  2. blue
  3. yellow
  4. green

Question 262.0 pts

Aspartic acid is a polypeptide side chain found in proteins. The pKa of aspartic acid is 3.86. If this polypeptide were in an aqueous solution with a pH of 7, the side chain would have what charge?
  1. there is no way to know
  2. negative
  3. positive
  4. neutral

Question 271.0 pts

Blood contains a buffer of carbonic acid (H2CO3) and hydrogen carbonate ion (HCO3-) that keeps the pH at a relatively stable 7.40. What is the ratio of [HCO3-] / [H2CO3] in blood? Ka1 = 4.30x10-7 for H2CO3. (Hint: Assume [CO32-] = 0)
  1. 1.71 x 10-14
  2. 3.98 x 10-8
  3. 10.8
  4. 0.0926

Question 282.0 pts

H2SO4 is a strong acid because the first proton ionizes 100%. The Ka of the second proton is 1.1x10-2. What would be the pH of a solution that is 0.100 M H2SO4? Account for the ionization of both protons.
  1. 0.963
  2. 0.955
  3. 2.05
  4. 1.00













CH302 · 50520 Principles of Chemistry II


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