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Universal Indicator Groupmates:

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Presentation on theme: "Universal Indicator Groupmates:"— Presentation transcript:

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

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