TO PREPARE ACID BASE INDICATOR FROM PLANT EXTRACT (RED HIBISCUS CHOROLLA)

MATERIAL REQUIREDS

Some red hibiscus flower, mortar and pestle, beaker, glass rod, distilled water, alcohol, filter paper, funnel, test tube, Bunsen burner, tripod stand with wire gauze, acid and base solution for test

THEORY

The chemical substance which gives H+ ion in aqueous solution are called acid for example hydrochloric acid, sulphuric acid, acetic acid etc. Base are the oxide or hydroxide of metal. The water soluble base are called alkali which gives OH- ion in aqueous solution . Sodium hydroxide, ammonium hydroxide, calcium oxide are the some example of base.

The H+ or OH – ion produce by acid or alkali change the color of indicator. According to the colour change we can distinguish the given sample is acid or alkali.

A reddish brown coloured pigment can be extracted from red hibiscus corolla which can be used as acid base indicator. It changes into pink colour under acid and changes into green colour under alkali.

PROCEDURE

• Take about 30 gram of red hibiscus corolla.
• Grind it on mortar and pestle to make paste.
• Then keep corolla paste on beaker and add about 50 ml of about 40% ethanol solution.
• Boil it for 2 minutes
• Then filter the extracted pigment by filter paper to obtain clear pigment solution.
• Finally acid base indicator is ready it can test with acid and base to find colour change.

OBSERVATION

S.N.	Indicator	Indicator colour	Acid	Alkali
1	Red Hibiscus corolla extract	reddish brown	pink	green

RESULT

Hibiscus corolla juice change into pink colour on acid and green on alkali.

CONCLUSION

Acid base indicator can be prepare from Red hibiscus corolla extract in laboratory.

PRECAUTION

• Do not use other part of flower except corolla.
• Use alcohol solution instead of water for complete extraction.
• Acid and base should be handle with care.