Neutralization Reaction Lab

1- The reaction HCl + KOH KCl + H2O is a

a. synthesis reaction c. neutralization reaction
b. ionization reaction d. decomposition reaction 2- What is the value of the self-ionization constant of water?

a. 0 c. 1.00 107
b. 1.00 1014 d. 55.4

3- Pure water contains
a. water molecules only.
b. hydronium ions only.
c. hydroxide ions only.
d. water molecules, hydronium ions, and hydroxide ions. 4- What is the concentration of OH- in pure water?
a. 1.00 107 M c. 55.4 M
b. 0.7 M d. 1.00 107 M 5- What is the pH of a neutral solution at 25°C?
a. 0 c. 7
b. 1 d. 14
6- A water solution whose pH is 4
a. is always neutral. c. is always acidic.
b. is always basic. d. might be neutral, basic or acidic. 7- A water solution whose pH is 10
a. is always neutral. c. is always acidic.
b. is always basic. d. might be neutral, basic or acidic. 8- The pH of a solution is 9. What is its H3O+ concentration?
a. 1 109 M c. 1 105 M
b. 1 107 M d. 9 M 9- The pH of a solution is 10. What is its OH- concentration?
a. 1.00 10 M c. 1.00 104 M
b. 1.00 10 M d. 10 M 10- What is the pH of a 1 104 M HCl solution?
a. 4 c. 8
b. 6 d. 10 11- What is the pH of a 1 105 M KOH solution?
a. 3 c. 9
b. 5 d. 11 12- If [H3O+] = 1.70 103 M, what is the pH of the solution?
a. 1.81 c. 2.42
b. 2.13 d. 2.77 13- What is the pH of a solution whose hydronium ion concentration is 5.03 101 M?
a. 0.298 c. 1.54
b. 0.513 d. 5.03 14- The pH range over which an indicator changes color is its
a. equivalence point. c. transition interval.
b. endpoint. d. pH interval. 15- Which of the following is not involved in neutralizations?
a. H3O+ ion
b. OHion
c. an acid and a base in an aqueous solution
d. neutral compound 16- In an acid-base titration, equivalent quantities of hydronium ions and hydroxide ions are present
a. at the beginning point. c. at the equivalency point.
b. at the midpoint. d. throughout the titration. 17- An indicator with which titration range would be appropriate to use during a titration of a strong acid with weak base?
a. pH 3.1–4.4 c. pH 6.0–7.6
b. pH 5.5–8.0 d. pH 8.0–9.6 18- What unknown quantity can be calculated after performing a titration?
a. volume c. mass
b. concentration d. density 19- What is the molarity of an HCl solution if 50.0 mL is neutralized in a titration by 40.0 mL of 0.400 M NaOH?
a. 0.200 M c. 0.320 M
b. 0.280 M d. 0.500 M 20- What is the molarity of NaOH solution if 3.47 mL is titrated by 11.1 mL of 0.0904 M HNO3?
a. 0.289 M c. 0.460 M
b. 0.355 M d. 0.620 M

COMPLETION
1. Pure water partially breaks down into hydronium ions and hydroxide ions in a process called ____________________.
2. The pH scale in general uses ranges from ____________________.
3. The pH of an acidic solution is ____________________ than 7.
4. The pH of a basic solution is ____________________ than 7.
5. An acidic solution makes the color of pH paper turn ____________________.
6. A basic solution turns the color of pH paper turn ____________________.
7. The compound that is produced by any neutralization reaction is ____________________.
8. An indicator with a transition interval of pH 9.2–11.0 would be used in a titration of a(n)
____________________ acid and a(n) ____________________ base.
9. The indicator _________________________ is used to study neutralizations of weak acids with strong bases.
10.The process that measures the amount of a solution of known concentration required to react with a measured amount of a solution of unknown concentration is called a(n) ____________________.
11. An acid-base titration involves a ____________________ reaction.
12. During a titration the volume of the titrant is measured with a(n)____________________.

SHORT ANSWER 1. What does the equation 2H2O(l) <--> H3O+(aq) + OH–(aq) represent?

2. What is a neutralization reaction?

3. In the reaction HCl(aq) + NaOH(aq) NaCl(aq) + H2O(l), identify the spectator ions.

4.
How can the equivalence point in a titration be detected by using a pH meter?

5. Describe a method to visually detect the end point of a titration without the use of instrumentation.

PROBLEM
1. What is the pH of a solution that has a hydronium ion concentration of 8.26 10–5 M?
ANS:
pH= –log[H3O+] = –log(8.26 10–5) = 4.08
2.What is the pH of a solution with a [OH–] of 3.31 10–7 M?
ANS:
pH7.52
3.What is the pH of a 0.004 50 M HCl solution?
ANS:
pH = –log [H3O+] = –log (4.50 10–3) = 2.35
4.What is the pH of a 0.067 0 M KOH solution?
ANS:
pH 12.8
5.What is the hydronium ion concentration of a solution that has a pH of 4.12?
ANS:
[H3O] 10pH 104.12 =7.59 109 M
6.What is the hydroxide ion concentration of a solution that has a pH of 8.57?
ANS:
[HO] 3.72 106 M

7.Why is it important to choose an indicator that has an end point that closely matches the equivalence point during a titration?
ANS:
At the equivalence point of a titration there will be a quick change in the pH because the two solutions are present in chemically equivalent amounts. If an indicator has an end point at a similar pH value as the equivalence point, the indictor will turn color when the volume of the titrant contains a chemically equivalent amount as the volume of the solution of unknown
concentration.

Answer key (Multiple choice)

Question | Answer | Question | Answer | 1 | C | 11 | C | 2 | B | 12 | D | 3 | D | 13 | A | 4 | A | 14 | C | 5 | C | 15 | D | 6 | C | 16 | C | 7 | B | 17 | A | 8 | A | 18 | B | 9 | C | 19 | C | 10 | A | 20 | A |

COMPLETION

1. self-ionization 2. 0 to 14 3. less 4. greater 5. red 6. blue 7. H2O 8. weak, strong 9. phenolphthalein 10. titration 11. neutralization 12. buret

SHORT ANSWER

1. The self-ionization of water. 2. A reaction of hydronium ions and hydroxide ions to form water molecules. 3. Cl–(aq) and Na+(aq) 4. The equivalence point is detected by noting a sharp change in the titration graph. 5. An indicator dye that changes color at different pH values works well as a visual detection method for titrations.