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192 Chemistry: Matter and Change
Solving Problems: A Chemistry Handbook
SOLVING PROBLEMS:
A CHEMISTRY HANDBOOK
CHAPTER 18
12. What is the molarity of a CsOH solution if 29.61 mL 0.2500M
HCl is needed to neutralize 60.00 mL solution?
13. A 70.0-mL sample of sulfuric acid solution is neutralized by
256.3 mL 0.100M NaOH solution. What is the molarity of the
sulfuric acid solution? (Hint: Note the mole ratio of the reactants in the balanced chemical equation.)
Buffered solutions It is often desirable to reduce variations in
pH when an acid or a base is added to a solution. A buffer is a solution that resists changes in pH when a moderate amount of acid or
base is added. A buffer is a mixture of a weak acid and its conjugate
base or a weak base and its conjugate acid. The buffer solution
reacts with H ϩ ions or OH Ϫ ions added to it, thus maintaining a
fairly constant pH value. An example of a buffer is the
CH 3 COOH/CH 3 COO Ϫ buffer system, which is made by mixing
equal molar amounts of acetic acid (CH 3 COOH) and an acetate salt
such as potassium acetate (KCH 3 COO) in water.
Chapter 18 Review
14. Explain how a base in the Arrhenius model is different from a
base in the Brønsted-Lowry model.
15. The K a value for acid X is 8.5 ϫ 10 Ϫ4 , while K a for acid Y is
4.6 ϫ 10 Ϫ8 . Explain what these K a values tell you about the
strengths of the two acids.
16. How does the pH of an aqueous solution change when there is a
decrease in the concentration of hydroxide ions? Explain your
answer.
17. Solution A has a pH of 9.0, and solution B has a pOH of 3.0.
State whether each solution is acidic, basic, or neutral. Which
solution has a higher concentration of hydrogen ions?
18. What is the molarity of a solution of HCl if the pH of the
solution is 2.00?
19. How can you detect the equivalence point of an acid-base
titration?
20. A chemist prepares a buffer solution by dissolving sodium
formate (NaHCOO) and another substance in water. What is
the other substance likely to be? Explain your answer.
▲
192 Chemistry: Matter and Change
Solving Problems: A Chemistry Handbook
SOLVING PROBLEMS:
A CHEMISTRY HANDBOOK
CHAPTER 18
12. What is the molarity of a CsOH solution if 29.61 mL 0.2500M
HCl is needed to neutralize 60.00 mL solution?
13. A 70.0-mL sample of sulfuric acid solution is neutralized by
256.3 mL 0.100M NaOH solution. What is the molarity of the
sulfuric acid solution? (Hint: Note the mole ratio of the reactants in the balanced chemical equation.)
Buffered solutions It is often desirable to reduce variations in
pH when an acid or a base is added to a solution. A buffer is a solution that resists changes in pH when a moderate amount of acid or
base is added. A buffer is a mixture of a weak acid and its conjugate
base or a weak base and its conjugate acid. The buffer solution
reacts with H ϩ ions or OH Ϫ ions added to it, thus maintaining a
fairly constant pH value. An example of a buffer is the
CH 3 COOH/CH 3 COO Ϫ buffer system, which is made by mixing
equal molar amounts of acetic acid (CH 3 COOH) and an acetate salt
such as potassium acetate (KCH 3 COO) in water.
Chapter 18 Review
14. Explain how a base in the Arrhenius model is different from a
base in the Brønsted-Lowry model.
15. The K a value for acid X is 8.5 ϫ 10 Ϫ4 , while K a for acid Y is
4.6 ϫ 10 Ϫ8 . Explain what these K a values tell you about the
strengths of the two acids.
16. How does the pH of an aqueous solution change when there is a
decrease in the concentration of hydroxide ions? Explain your
answer.
17. Solution A has a pH of 9.0, and solution B has a pOH of 3.0.
State whether each solution is acidic, basic, or neutral. Which
solution has a higher concentration of hydrogen ions?
18. What is the molarity of a solution of HCl if the pH of the
solution is 2.00?
19. How can you detect the equivalence point of an acid-base
titration?
20. A chemist prepares a buffer solution by dissolving sodium
formate (NaHCOO) and another substance in water. What is
the other substance likely to be? Explain your answer.
▲