- Sprite does not contain phosphoric acid. Only sodas that are dark in color contain this acid. sodas such as Sprite contain citric acid, sugar, and carbonaled water Design a simple experiment to determine the concentration of citric acid in SpriteProvide a de tailed procedure
The correct answer and explanation is:
Experiment to Determine the Concentration of Citric Acid in Sprite
Objective
To determine the concentration of citric acid in Sprite using an acid-base titration with a standardized sodium hydroxide (NaOH) solution.
Materials:
- Sprite (Sample)
- 0.100 M Sodium Hydroxide (NaOH) Solution (Standardized)
- Phenolphthalein Indicator
- Burette (50 mL)
- Pipette (25 mL)
- Erlenmeyer Flask (250 mL)
- Distilled Water
- Magnetic Stirrer (Optional)
- White Tile (for visualizing color change)
- Graduated Cylinder
Procedure:
- Prepare the Sample:
- Open a bottle of Sprite and let it sit for 24 hours to remove dissolved carbon dioxide.
- Pipette 25.00 mL of degassed Sprite into a 250 mL Erlenmeyer flask.
- Add Indicator:
- Add 2-3 drops of phenolphthalein indicator into the flask.
- The solution will remain colorless since citric acid is weak.
- Setup the Burette:
- Fill a 50 mL burette with 0.100 M NaOH solution.
- Record the initial volume.
- Titration:
- Slowly add NaOH while swirling the flask continuously.
- As NaOH neutralizes the citric acid, a faint pink color appears and then disappears.
- Continue adding dropwise until the solution retains a persistent light pink color for 30 seconds.
- Record the final burette reading.
- Calculate Citric Acid Concentration:
- Citric acid ((C_6H_8O_7)) reacts with NaOH in a 1:3 molar ratio:
[
C_6H_8O_7 + 3NaOH \rightarrow Na_3C_6H_5O_7 + 3H_2O
] - Calculate the moles of NaOH used:
[
\text{Moles of NaOH} = M_{NaOH} \times V_{NaOH}
] - Find moles of citric acid:
[
\text{Moles of Citric Acid} = \frac{\text{Moles of NaOH}}{3}
] - Compute concentration:
[
C_{\text{Citric Acid}} = \frac{\text{Moles of Citric Acid}}{V_{\text{Sprite}}}
]
Explanation
Acid-base titration is an analytical technique used to determine unknown acid concentrations. In this experiment, we measure the citric acid concentration in Sprite by neutralizing it with sodium hydroxide (NaOH). Since citric acid is a triprotic acid ((C_6H_8O_7)), it reacts with NaOH in a 1:3 ratio.
First, we let the Sprite sit to remove carbon dioxide, which could interfere with the titration. Using a pipette, a precise volume (25.00 mL) of degassed Sprite is transferred into an Erlenmeyer flask, and phenolphthalein is added as an indicator. This helps visualize the reaction’s endpoint.
A burette containing standardized 0.100 M NaOH is used to titrate the citric acid. As NaOH is added, it gradually neutralizes the acid, forming sodium citrate and water. Initially, the solution remains colorless, but as the endpoint nears, a faint pink color appears. The titration ends when the solution maintains this color for at least 30 seconds, indicating complete neutralization.
By recording the volume of NaOH required, we calculate the moles of base reacted. Since citric acid reacts in a 1:3 ratio with NaOH, dividing the NaOH moles by 3 gives the citric acid moles. Finally, dividing by the sample volume gives the concentration in molarity ((M)).
This method is efficient and widely used in food chemistry to determine acid content in beverages. The obtained concentration helps in quality control and nutritional labeling. The titration method provides accurate, reproducible results and can be applied to other acidic drinks.
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