1. Universal Indicator Groupmates:
Carmen Cheung (4) Chris Chow (7) Sandy Luk (21) Gary Ma (25) Hendrick Wong (28) Brian Wong (29)

2. Introduction Acid-base indicator  color change with pH
Detect acidity and alkalinity
Plant pigments
 colour dependent of pH

3. Aims Explore  Extraction of natural indicators  Color change
Determine
 Which plant can be an indicator
 Which can cover the pH range

4. Goggles Water bath  Prevent direct heating
Precautions
Goggles
Water bath  Prevent direct heating

5. Apparatus and Chemicals used
Fruits - oranges, apples, grapes
Vegetables - beetroot, spinach, cauliflower, ginger, chili
Flowers – carnation, hibiscus
Mortar and pestle
Test tube
Test tube rack
Beaker
Dropper
Ethanol
Stirring rods
Deionized or distilled water
0.1M HCl (aq) (pH1)
NaOH(s)
100cm3 and 10cm3 Measuring cylinder

6. Procedures Preparing pH 1-14 solutions Extracting the indicator
Testing the pH solutions with the indicators prepared
Testing the solutions with methyl orange and phenolphthalein
Comparing the color changes of the indicators

7. Methyl Orange & Phenolphthalein
Result
Hibiscus
Methyl Orange & Phenolphthalein

8. Result

9. Discussion
Questions
Why hibiscus can as the indicator for different pH ?
Contains anthocyanine [1,2]
Pigment  Pink, red, purple, violet and blue
Dye extracted  Changes its colour  Hydrogen ion conc. of the solution

10. Discussion Why other substance used can only detect the pH of alkali ?
Equivalence point obtained
 Coincident the one by standard indicator
Flower extract
 Use of mixed indicator

11. Discussion
3. Any differences between the efficiency of hibiscus and phenolphthalein ?
Hibiscus indicator
Phenolphthalein
Different pH values of the testing solutions
Cannot shows the pH values
Different colors in these solutions
Acidic  Colorless
Alkaline  Pink
Sharp color change
 Easy to detect end-point
Gradual color change
 Uneasy to find the end-point

12. Discussion Error & Improvement Experiment was carried out once only
 Carried again
 Raise the accuracy
Titration has not been carried out
 Titration should be carried out
 With methyl orange, phenolphthalein and
hibiscus indicator respectively
 Color change can be observed

13. Discussion Only parts of flowers & fruits crushed to make indicators
 Should be crushed more times
 Should be used twice by one titration

14. Discussion
Conc. of flowers & fruits in indicators for color change not investigated
 Different conc. of the flowers and
fruits in indicators
 Different effects on color change
 Indicator of different conc. should be
prepared in each titration

15. Discussion Solution extracted in foam state  Not pure enough
 Affected color change

16. Discussion Limitation
 Inaccurate equipment for extracting pure solution

17. Hibiscus  Universal indicator Distinct color changes
Conclusion
Hibiscus  Universal indicator
Distinct color changes

18. Reflection Poor time management Poor preparation A gain of knowledge
Deeper interest in Chemistry

19. Universal Indicator
The End