Study of Acidity of Different Tea Leaves | Chemistry Investigatory Project (Class XI)
Chemistry Project: Acidity Comparison of Tea Leaves Using Titration Method
📘 CHEMISTRY INVESTIGATORY PROJECT
STUDY OF THE ACIDITY OF DIFFERENT SAMPLES OF TEA LEAVES
🧾 COVER PAGE
CHEMISTRY INVESTIGATORY PROJECT
ON
“Study of the Acidity of Different Samples of Tea Leaves”
Submitted By:
Name: ____________
Class: XI
Roll No.: ____________
School: ____________
Session: ____________
Submitted To:
Chemistry Teacher: ____________
🏫 CERTIFICATE
This is to certify that ____________ of Class XI has successfully completed the Chemistry Investigatory Project titled “Study of the Acidity of Different Samples of Tea Leaves” under the guidance of the Chemistry teacher during the academic session ____________.
Teacher's Signature: ____________
Examiner's Signature: ____________
Date: ____________
🙏 ACKNOWLEDGEMENT
I express my sincere gratitude to my Chemistry teacher for valuable guidance and encouragement throughout this project. I am also thankful to my school laboratory staff for providing the required chemicals and apparatus. Their support helped me complete this investigation successfully.
📑 INDEX
- Introduction
- Aim
- Theory
- Materials Required
- Procedure
- Observations
- Calculations
- Result
- Conclusion
- Precautions
- Research and Experimentation
- Analysis
- Limitation of the Study
- Bibliography
1. INTRODUCTION
Tea is one of the most widely consumed beverages in the world. It contains compounds like tannins, polyphenols, catechins, caffeine, and organic acids. These contribute to its acidic nature and taste.
Different processing methods such as fermentation, drying, and blending affect the chemical composition of tea leaves, resulting in variation in acidity among different tea types.
2. AIM
To determine and compare the acidity of different samples of tea leaves.
3. THEORY
Tea contains weak organic acids such as tannic acid and gallic acid. These acids react with a base (NaOH) in a neutralization reaction:
Acid + Base → Salt + Water
The amount of NaOH required for neutralization is directly proportional to the acidity of the tea sample.
4. MATERIALS REQUIRED
- Different tea samples
- Distilled water
- Burette
- Pipette
- Conical flask
- Beakers
- 0.1 N NaOH solution
- Phenolphthalein indicator
- Funnel
- Filter paper
- Measuring cylinder
5. PROCEDURE
 |
| Titration setup used to compare the acidity of different tea leaf extracts using NaOH and phenolphthalein indicator. |
| (A) Preparation of Tea Extract |
- Take 5 g of each tea sample.
- Add 100 mL distilled water and boil for 10 minutes.
- Filter and cool the extract.
- Label each sample properly.
(B) Titration
- Fill burette with NaOH solution.
- Pipette 20 mL tea extract into conical flask.
- Add 2–3 drops phenolphthalein.
- Titrate with NaOH until faint pink colour appears.
- Note readings and repeat for all samples.
6. OBSERVATION TABLE
| Tea Sample | Volume of Tea Extract (mL) | Volume of NaOH Used (mL) | Relative Acidity |
|---|---|---|---|
| Green Tea (A) | 20 | 4.2 | Low |
| Black Tea (B) | 20 | 6.8 | High |
| Herbal Tea (C) | 20 | 3.5 | Very Low |
| Dust Tea (D) | 20 | 7.5 | Very High |
 |
|
7. CALCULATIONS
Using: N₁V₁ = N₂V₂
Where:
N₁ = Normality of tea extract
V₁ = Volume of tea extract
N₂ = Normality of NaOH
V₂ = Volume of NaOH used
Acidity is proportional to NaOH consumed.
8. RESULT
Dust Tea showed the highest acidity, while Herbal Tea showed the lowest acidity among the tested samples.
9. CONCLUSION
Different tea samples show different acidity levels depending on their processing and chemical composition. Dust tea and black tea are more acidic compared to green and herbal teas.
10. PRECAUTIONS
- Use freshly prepared tea extracts
- Rinse burette and pipette properly
- Avoid parallax error
- Add indicator dropwise
- Perform titration slowly near endpoint
- Repeat readings for accuracy
11. RESEARCH AND EXPERIMENTATION
This study was performed using acid–base titration of tea extracts with NaOH. Equal quantities of tea were boiled, filtered, and titrated using phenolphthalein as an indicator to determine relative acidity.
12. ANALYSIS
Dust tea required the highest NaOH volume, indicating highest acidity. Herbal tea showed the lowest acidity. Differences are due to variation in processing methods and chemical composition of tea leaves.
13. LIMITATION OF THE STUDY
- Exact acids present cannot be individually identified
- Human error in detecting endpoint
- Variation in heating temperature
- Limited sample size
- Only one indicator used
14. BIBLIOGRAPHY
- NCERT Chemistry Laboratory Manual Class XI
- NCERT Chemistry Textbook Class XI
- O.P. Pandey – Practical Chemistry
- Modern ABC of Chemistry
- Vogel’s Quantitative Chemical Analysis
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