CHY 105 Fundamentals of Chemistry

Learning Objectives and Suggested Problems for Chapters 15 and 16

See Practice Acid/Base Questions at the end of the objectives.

Chapter 15: Acids and Bases

You should be able to:

1. Give the Arrhenius and Bronsted-Lowry definitions of acid and base.

2. Give properties of acids and bases

3. Write chemical reactions that show how acids and bases dissolve in water.

4. Write chemical reactions that show a strong acid a reacting with water and a weak acid acid reacting with water

5. Identify the acid, base, conjugate acid, conjugate base in a reaction.

6. Explain why H+ and H3O+ can be used interchangeably.

7. Distinguish between strong acids and weak acids. Give examples of strong and weak acids. Understand Figure 15.1 on page 462. Know that all carboxylic acids are weak (organic) acids.

8. Define the term amphoteric and give an example of an amphoteric substance.

9. Write the chemical reaction that describes the self-ionization of water.

10. State the concentration of hydronium (or hydrogen) ions and hydroxide ions in water.

11. Know that in all aqueous solutions that the [hydronium ions] x [hydroxide ions] = 1 x 10-14

12. Given the concentration of hydronium or hydroxide ions determine: the concentration of the other ion, and the pH of the solution, and identify the solution as either acid, base, or neutral.

13. Give the relative concentration of hydronium (hydrogen) ions and hydroxide ions present in acid, base, and neutral solutions.

14. Given a solution's pH identify the solution as acid, base, or neutral and state the concentration of hydronium ions and hydroxide ions in the solution.

15. Describe the pH scale.

16. Give the pHs associated with acid, base, neutral.

17. State how the acidity or basicity changes as pH changes, meaning:

18. Give the color of the acid-base indicator phenolphthalein is acid, base, and neutral solutions (see Chemistry in Focus on page 468.)

19.  Define the term acid base indicator and give examples of acid base indicators.

20. State the color (or color changes) of litmus paper in acid, base and neutral.  Do the same for phenolphthalein.

21.  Describe buffers.  State how the pH of a buffer changes when acid or base is added. Give an example of a buffered solution.

BUFFERS:  Buffers are solutions that resist changing pH when acid or base is added.  When a drop of fairly concentrated acid is added to water the pH changes dramatically.  When a drop of the same acid is added to a buffer the pH will hardly change at all.  Most fluids in the human body are buffered as it is extremely important to maintain the pH of body fluids within a very narrow range.  If you blood pH is too high or too low for more than a day or two you will die!  Buffers can be made from weak acids or weak bases, but not from strong acids.  (This means that the fluids in your stomach are not buffered as the acid in your stomach is a strong acid.)

Suggested End of Chapter Questions: In class discussions: 1-7, 12;  Questions and Problems:  1-3, 5, 6, 9 and 10 (identify acid base, conjugate acis and conjugate base for each -- note any 2 substances that differ by only a single H+ are called a conjugate acid/base pair), 16-18, 21-23, 27, 30, 37, 38, 40, 59, 60, 63, 67, 68, 70, 73-75, 77, 78, 79, 82 (fyi - a solution with a pOH of 4 has a pH of 10), 84, 89, and the questions below

+Other: (ANSWERS CAN BE FOUND BELOW)

1. Consider a solution with a hydroxide concentration of 1.0 x 10-3 M.

a. Give the concentration of hydronium ions in this solution.

b. Identify the solution as acid, base or neutral.

c. State the color of phenolphthalein in this solution.

d. State how/if the color of red litmus will change in this solution.

e. State how/if the color of blue litmus will change in this solution.

f. Is this solution more or less basic than a solution of pH 9?

2. Consider a solution with a pH of 3.

a. Is this solution an acid, base. or neutral?

b. What is the concentration of hydrogen ions and of hydroxide ions in this solution?

c. Is this solution more or less acidic than a solution of pH 4? How much more or less acidic is the pH 3 solution when compared to a solution of pH 4?

d. Is this solution more or less acidic than a solution of pH 5? How much more or less acidic is the pH 3 solution when compared to a solution of pH 5?

Chapter 16.1, 16.2: How Chemical Reactions Occur & Conditions that Affect Reaction Rates

You should be able to:

  1. State collision theory of a chemical reaction and explain why some collisions do not result in a chemical reaction.
  2. Draw, label energy, and recognize diagrams for endothermic and exothermic reactions.
  3. Define the terms endothermic and exothermic.
  4. Explain the impact of each of the following on the rate of a chemical reaction:
    1. size of the activation energy (Ea)
    2. temperature
    3. concentration of the reactants
    4. size of the activation energy
    5. catalysts (lower the activation energy and thus, speed up chemical reactions)
    6. size of reacting molecule (not in book - the larger the molecule the slower the reaction as collisions of proper orientation are less likely for large reactants)
    Suggested End of Chapter Questions: 1-6

    Collision Theory Links - some of the information is at a higher level than presented in class, but I think you will find the reading of the information on these sites reinforces what you have learned.

ANSWERS:

1. Consider a solution with a hydroxide concentration of 1.0 x 10-3 M.

a. Give the concentration of hydronium ions in this solution. 1.0 x 10-11 M

b. Identify the solution as acid, base or neutral. (pH = 11, therefore solution is basic)

c. State the color of phenolphthalein in this solution. pink

d. State how/if the color of red litmus will change in this solution. red litmus will turn blue in base

e. State how/if the color of blue litmus will change in this solution. blue litmus will not change color in base

f. Is this solution more or less basic than a solution of pH 9? This solution is 100 times more basic than a solution of pH 9.

2. Consider a solution with a pH of 3.

a. Is this solution an acid, base. or neutral? acid

b. What is the concentration of hydrogen ions and of hydroxide ions in this solution? Hydrogen ion conc. = 1.0 x 10-3 M, hydroxide ion con. = 1.0 x 10-11 M

c. Is this solution more or less acidic than a solution of pH 4? How much more or less acidic is the pH 3 solution when compared to a solution of pH 4? A pH 3 solution is 10 times more acidic than a solution of pH 4.

d. Is this solution more or less acidic than a solution of pH 5? How much more or less acidic is the pH 3 solution when compared to a solution of pH 5? A pH 3 solution is 100 times more acidic than a solution of pH 5.