Acid-Base Chemistry
Lab Report Assistant
This document is not meant to be a substitute for a formal laboratory report. The Lab Report Assistant is simply a summary of the experiment's questions, diagrams if needed, and data tables that should be addressed in a formal lab report. The intent is to facilitate students' writing of lab reports by providing this information in an editable file which can be sent to an instructor.
Exercise 1: Using pH Paper and the Indicator Bromothymol Blue (BTB)
Data Table 1. Data Collected from Exercise 1.
|
ID Number
|
Chemical Name
|
Chemical Formula
|
Hypothesis: Acid or Base
|
pH
|
BTB Color
|
Acid or Base?
|
|
11A
|
Acetic acid
|
CH3COOH
|
Acid
|
5
|
Yellow
|
Acid
|
|
11B
|
Hydrogen nitrate
|
HNO3
|
Acid
|
2
|
Yellow
|
Acid
|
|
11C
|
Hydrogen sulfate
|
H2SO4
|
Acid
|
2
|
Yellow
|
Acid
|
|
11D
|
Phosphoric acid
|
H3PO4
|
Acid
|
4
|
Yellow
|
Acid
|
|
11E
|
Sodium acetate
|
CH3COONa
|
Acid
|
7
|
Blue
|
Base
|
|
11F
|
Sodium bicarbonate
|
NaHCO3
|
Base
|
10
|
Blue
|
Base
|
|
11G
|
Sodium dihydrogen phosphate
|
NaH2PO4
|
Acid
|
6
|
Yellow
|
Acid
|
|
11H
|
Sodium hydrogen sulfate
|
NaHSO4
|
Acid
|
4
|
Yellow
|
Acid
|
|
12A
|
Sodium bisulfite
|
NaHSO3
|
Acid
|
4
|
Yellow
|
Acid
|
|
12B
|
Limewater
|
Ca(OH)2
|
Base
|
12
|
Blue
|
Base
|
|
12C
|
Trisodium phosphate
|
Na3PO4
|
Base
|
12
|
Blue
|
Base
|
|
12D
|
Disodium hydrogen orthophosphate
|
Na2HPO4
|
Base
|
8
|
Blue
|
Base
|
|
12E
|
Ammonium hydroxide
|
NH4OH
|
Base
|
10
|
Blue
|
Base
|
|
12F
|
Hydrochloric acid
|
HCl
|
Acid
|
2
|
Yellow
|
Acid
|
|
12G
|
Sodium carbonate
|
Na2CO3
|
Acid
|
11
|
Blue
|
Base
|
|
12H
|
Sodium hydroxide
|
NaOH
|
Base
|
12
|
Blue
|
Base
|
Questions
A. When you created hypotheses to guess whether each chemical was an acid or base, what specifically did you look for in the chemical formulas?
B. What is the value of using pH paper as an indicator?
C. What is the value of using BTB as an indicator? When might BTB be a better choice than pH paper?
D. Write the chemical equation of mixing hydrogen nitrate (HNO3) with water.
E. Write the chemical equation of mixing ammonium hydroxide (NH4OH) with water.
F. What are the conjugate acids and conjugate bases of questions D and E?
Exercise 2: Acid-Base Reactions
Data Table 2. Acid-Base Reactions.
|
|
A1:
Acetic acid (CH3COOH)
|
A2:
Hydrogen nitrate (HNO3)
|
A3:
Hydrogen sulfate (H2SO4)
|
A4:
Phosphoric acid (H3PO4)
|
A5:
Sodium dihydrogen phosphate (NaH2PO4)
|
A6:
Sodium hydrogen sulfate (NaHSO4)
|
A7:
Sodium bisulfite (NaHSO3)
|
A8:
Hydrochloric acid (HCl)
|
|
BA:
Sodium acetate (CH3COONa)
|
pH:6
BTB color:
Yellow
|
pH:3
BTB color:
Yellow
|
pH:4
BTB color:
Yellow
|
pH:5
BTB color:
Yellow
|
pH:7
BTB color:
Yellow
|
pH:6
BTB color:
Yellow
|
pH:7
BTB color:
Yellow
|
pH:2
BTB color:
Yellow
|
|
BB:
Sodium bicarbonate (NaHCO3)
|
pH:7
BTB color:
Blue
|
pH:4
BTB color:
Yellow
|
pH:4
BTB color:
Yellow
|
pH:6
BTB color:
Yellow
|
pH:8
BTB color:
Blue
|
pH:10
BTB color:
Blue
|
pH:10
BTB color:
Blue
|
pH:2
BTB color:
Yellow
|
|
BC:
Limewater [Ca(OH)2]
|
pH:6
BTB color:
Yellow
|
pH:2
BTB color:
Yellow
|
pH:2
BTB color:
Yellow
|
pH:4
BTB color:
Yellow
|
pH:7
BTB color:
Yellow
|
pH:4
BTB color:
Yellow
|
pH:4
BTB color:
Yellow
|
pH:2
BTB color:
Yellow
|
|
BD:
Trisodium phosphate (Na3PO4)
|
pH:6
BTB color:
Yellow
|
pH:2
BTB color:
Yellow
|
pH:2
BTB color:
Yellow
|
pH:4
BTB color:
Yellow
|
pH:7
BTB color:
Blue-Green
|
pH:7
BTB color:
Blue
|
pH:10
BTB color:
Blue
|
pH:2
BTB color:
Yellow
|
|
BE:
Disodium hydrogen orthophos-phate (Na2HPO4)
|
pH:6
BTB color:
Yellow
|
pH:2
BTB color:
Yellow
|
pH:3
BTB color:
Yellow
|
pH:4
BTB color:
Yellow
|
pH:8
BTB color:
Blue-Green
|
pH:7
BTB color:
Blue-Green
|
pH:8
BTB color:
Blue-Green
|
pH:2
BTB color:
Yellow
|
|
BF:
Ammonium hydroxide (NH4OH)
|
pH:7
BTB color:
Yellow
|
pH:2
BTB color:
Yellow
|
pH:2
BTB color:
Yellow
|
pH:5
BTB color:
Yellow
|
pH:8
BTB color:
Blue-Green
|
pH:10
BTB color:
Blue
|
pH:10
BTB color:
Blue
|
pH:2
BTB color:
Yellow
|
|
BG:
Sodium carbonate (Na2CO3)
|
pH:10
BTB color:
Blue
|
pH:9
BTB color:
Blue
|
pH:4
BTB color:
Yellow
|
pH:7
BTB color:
Blue-Green
|
pH:9
BTB color:
Blue
|
pH:11
BTB color:
Blue
|
pH:10
BTB color:
Blue
|
pH:7
BTB color:
Blue
|
|
BH:
Sodium hydroxide (NaOH)
|
pH:6
BTB color:
Yellow
|
pH:2
BTB color:
Yellow
|
pH:3
BTB color:
Yellow
|
pH:4
BTB color:
Yellow
|
pH:10
BTB color:
Blue
|
pH:12
BTB color:
Blue
|
pH:12
BTB color:
Blue
|
pH:2
BTB color:
Yellow
|
Questions
A. Visually analyze the wells colored with BTB, and remember that acids are organized by columns and bases are organized by rows. What specific acids or bases are weak or strong acids or bases? Explain why.
B. Why did some of the chemicals neutralize and others did not?
C. Did any of the mixtures get more acidic than the original acid or less acidic than the original base? Why do you think this happened or did not happen?
Exercise 3: Testing the pH of Household Products
Data Table 3. Household Acids and Bases.
|
Household substance
|
Prediction:
(Acid, Base, or Neutral)
|
pH Value
|
Conclusion:
(Acid, Base, or Neutral)
|
|
Vinegar
|
Acid
|
4
|
Acid
|
|
Bleach
|
Acid
|
8
|
Base
|
|
Milk
|
Base
|
8
|
Base
|
|
Ginger Ale
|
Acid
|
6
|
Acid
|
|
Bug Spray
|
Base
|
8
|
Base
|
Questions
A. What properties did you use to determine whether the substances you tested were acid or base?
B. Did any of your findings surprise you? Why or why not?