Chem 144 Experiment 5: Quantitative Determination
of an Acid in Carbonated Beverages
Complete Study Guide 2025/2026 | 150 Q&A | 100% Verified
EXAM DETAILS
| Attribute | Information |
|--|-|
| Course | Chem 144 / CHM 144 / CHM 144L |
| Experiment | 5: The Quantitative Determination of an Acid in Carbonated Beverages |
| Parts | Part 1: Traditional Titration with Indicator Dye; Part 2: Modern Titration with pH Probe |
| Key Concepts | Acid-base titration, stoichiometry, citric acid, equivalence point, standard
solution |
| Format | 150 Questions & Answers with Explanations |
SECTION 1: TITRATION FUNDAMENTALS
Questions 1–30
Question 1
In Experiment 5, what substance are students determining the concentration of in a carbonated
beverage?
Answer: Citric acid
Rationale: Students determine the concentration of citric acid (H₃C₆H₅O₇) in a carbonated
beverage using a solution of sodium hydroxide (NaOH) of known concentration .
Question 2
Using a solution of known concentration to determine the concentration of another solution
through a monitored reaction of known stoichiometry that goes to completion is called a(n)
_____.
,Answer: Titration
Rationale: Titration is the standard analytical technique where a titrant of known concentration is
added to a solution of unknown concentration until the reaction is complete .
Question 3
In the acid-base reaction of aqueous citric acid with aqueous sodium hydroxide, how many
moles of base are needed to neutralize one mole of citric acid?
Answer: 3 moles of NaOH
Rationale: Citric acid (H₃C₆H₅O₇) is a triprotic acid, meaning it contains three acidic hydrogen
atoms that can be neutralized by three hydroxide ions. The balanced equation is: H₃C₆H₅O₇ (aq)
+ 3 OH⁻ (aq) → 3 H₂O (l) + C₆H₅O₇³⁻ (aq) .
Question 4
The equivalence point occurs when:
Answer: The number of moles of acid is stoichiometrically equal to the number of moles of base
added
Rationale: The equivalence point is reached when the moles of acid are stoichiometrically equal
to the moles of base added to neutralize the acid .
Question 5
For acid-base titrations, the most common methods to monitor the equivalence point rely on
measuring:
Answer: pH
Rationale: In acid-base titrations, pH monitoring is used to determine when the equivalence
point has been reached. This can be done using an indicator dye (phenolphthalein) or a pH
probe .
,Question 6
For the acid-base reaction of citric acid and sodium hydroxide, the equivalence point occurs at
which pH?
Answer: 8.5
Rationale: The equivalence point of the citric acid and sodium hydroxide reaction occurs at pH
8.5. This is because the neutralization of citric acid, a weak acid, with a strong base (NaOH)
results in a basic equivalence point .
Question 7
Which device is used to both deliver and measure the volume of sodium hydroxide (NaOH) to
the citric acid solution?
Answer: Buret
Rationale: A buret is used to both deliver and measure the volume of sodium hydroxide (NaOH)
to the citric acid solution during the titration .
Question 8
Including both rapid and accurate titrations, how many trials will be conducted in Part 1
(Traditional Titration Using an Indicator Dye)?
Answer: 5 trials
Rationale: Including both rapid and accurate titrations, students will conduct 5 trials in
Procedure 1 .
Question 9
If 25.31 mL of 0.0500 M NaOH solution is required to reach the equivalence point of an
acid-base titration of 40.0 mL of 7-Up, how many moles of NaOH were required?
Answer: 0.00127 moles
, Rationale: Moles = Volume (L) × Molarity = 0.02531 L × 0.0500 M = 0.0012655 moles. Rounded
to correct significant figures = 0.00127 moles .
Question 10
Based on the previous question (25.31 mL of 0.0500 M NaOH), how many moles of citric acid
are in the 40.0 mL of 7-Up?
Answer: 0.000423 moles
Rationale: Since the ratio of NaOH to citric acid is 3:1, moles of citric acid = 0.00127 moles ÷ 3 =
0.000423 moles .
Question 11
Which soda from Set 2 cannot be titrated using the traditional phenolphthalein method?
Answer: Orange Crush
Rationale: Orange Crush has a color that would interfere with the visual detection of the
phenolphthalein endpoint, so it must be titrated using the modern pH probe method .
Question 12
What is the purpose of boiling the soda before titration?
Answer: To remove carbonic acid (CO₂)
Rationale: Carbonated beverages contain carbonic acid from dissolved CO₂. The soda is boiled
to remove carbonic acid, allowing accurate determination of citric acid concentration without
interference from carbonic acid .
Question 13
What are the two titration methods compared in Experiment 5?
of an Acid in Carbonated Beverages
Complete Study Guide 2025/2026 | 150 Q&A | 100% Verified
EXAM DETAILS
| Attribute | Information |
|--|-|
| Course | Chem 144 / CHM 144 / CHM 144L |
| Experiment | 5: The Quantitative Determination of an Acid in Carbonated Beverages |
| Parts | Part 1: Traditional Titration with Indicator Dye; Part 2: Modern Titration with pH Probe |
| Key Concepts | Acid-base titration, stoichiometry, citric acid, equivalence point, standard
solution |
| Format | 150 Questions & Answers with Explanations |
SECTION 1: TITRATION FUNDAMENTALS
Questions 1–30
Question 1
In Experiment 5, what substance are students determining the concentration of in a carbonated
beverage?
Answer: Citric acid
Rationale: Students determine the concentration of citric acid (H₃C₆H₅O₇) in a carbonated
beverage using a solution of sodium hydroxide (NaOH) of known concentration .
Question 2
Using a solution of known concentration to determine the concentration of another solution
through a monitored reaction of known stoichiometry that goes to completion is called a(n)
_____.
,Answer: Titration
Rationale: Titration is the standard analytical technique where a titrant of known concentration is
added to a solution of unknown concentration until the reaction is complete .
Question 3
In the acid-base reaction of aqueous citric acid with aqueous sodium hydroxide, how many
moles of base are needed to neutralize one mole of citric acid?
Answer: 3 moles of NaOH
Rationale: Citric acid (H₃C₆H₅O₇) is a triprotic acid, meaning it contains three acidic hydrogen
atoms that can be neutralized by three hydroxide ions. The balanced equation is: H₃C₆H₅O₇ (aq)
+ 3 OH⁻ (aq) → 3 H₂O (l) + C₆H₅O₇³⁻ (aq) .
Question 4
The equivalence point occurs when:
Answer: The number of moles of acid is stoichiometrically equal to the number of moles of base
added
Rationale: The equivalence point is reached when the moles of acid are stoichiometrically equal
to the moles of base added to neutralize the acid .
Question 5
For acid-base titrations, the most common methods to monitor the equivalence point rely on
measuring:
Answer: pH
Rationale: In acid-base titrations, pH monitoring is used to determine when the equivalence
point has been reached. This can be done using an indicator dye (phenolphthalein) or a pH
probe .
,Question 6
For the acid-base reaction of citric acid and sodium hydroxide, the equivalence point occurs at
which pH?
Answer: 8.5
Rationale: The equivalence point of the citric acid and sodium hydroxide reaction occurs at pH
8.5. This is because the neutralization of citric acid, a weak acid, with a strong base (NaOH)
results in a basic equivalence point .
Question 7
Which device is used to both deliver and measure the volume of sodium hydroxide (NaOH) to
the citric acid solution?
Answer: Buret
Rationale: A buret is used to both deliver and measure the volume of sodium hydroxide (NaOH)
to the citric acid solution during the titration .
Question 8
Including both rapid and accurate titrations, how many trials will be conducted in Part 1
(Traditional Titration Using an Indicator Dye)?
Answer: 5 trials
Rationale: Including both rapid and accurate titrations, students will conduct 5 trials in
Procedure 1 .
Question 9
If 25.31 mL of 0.0500 M NaOH solution is required to reach the equivalence point of an
acid-base titration of 40.0 mL of 7-Up, how many moles of NaOH were required?
Answer: 0.00127 moles
, Rationale: Moles = Volume (L) × Molarity = 0.02531 L × 0.0500 M = 0.0012655 moles. Rounded
to correct significant figures = 0.00127 moles .
Question 10
Based on the previous question (25.31 mL of 0.0500 M NaOH), how many moles of citric acid
are in the 40.0 mL of 7-Up?
Answer: 0.000423 moles
Rationale: Since the ratio of NaOH to citric acid is 3:1, moles of citric acid = 0.00127 moles ÷ 3 =
0.000423 moles .
Question 11
Which soda from Set 2 cannot be titrated using the traditional phenolphthalein method?
Answer: Orange Crush
Rationale: Orange Crush has a color that would interfere with the visual detection of the
phenolphthalein endpoint, so it must be titrated using the modern pH probe method .
Question 12
What is the purpose of boiling the soda before titration?
Answer: To remove carbonic acid (CO₂)
Rationale: Carbonated beverages contain carbonic acid from dissolved CO₂. The soda is boiled
to remove carbonic acid, allowing accurate determination of citric acid concentration without
interference from carbonic acid .
Question 13
What are the two titration methods compared in Experiment 5?
