Page 34 - Big Ideas Year 10 sciPAD 2025

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34 SCIPAD - BIG IDEAS - BOOK 2
BASIS OF CHEMICAL REACTIONS
Making Indicators
Aim: To make acid-base indicators using everyday substances.
Equipment: Red cabbage, tea, beetroot, turmeric, cranberry juice, a beaker, water, tripod,
Bunsen burner, gauze mat, 1.0 mol L-1
HCl and 1.0 mol L-1
NaOH, pipette.
Method:
Task One
For the Cranberry Juice
Pour into a beaker and leave to one side.
For Cabbage and Beetroot
Chop the cabbage into small pieces
until you have enough to fill 2 cups.
Place the cabbage in a large beaker
and add water to cover the cabbage.
Boil over a Bunsen burner for at least ten
minutes for the colour to leach out of
the cabbage.
Filter out the plant material to keep
the red-purple-bluish coloured liquid.
This liquid is at about pH 7. (The exact
colour you get depends on the pH of
the water.)
Place in a small beaker and leave to
one side.
Repeat this method for the beetroot.
For the Turmeric
Mix 1 teaspoon turmeric in 100 mL cup of
alcohol.
Place in a small beaker and leave to one side.
For the Tea
Put 100 ml of water into a beaker and boil.
Turn off the Bunsen burner and put three tea
bags in the beaker.
Remove the tea bags when the tea is very
strong.
Place in a small beaker and leave to one side.
Task Two
1. You now have five beakers, each containing a different indicator.
2. Using a pipette, place 5 mL of the cabbage indicator into two test tubes.
3. Add 5 ml of HCl (acid) to one test tube and 5 mL of NaOH (alkali) to the other test tube.
4. Record the colour change on the table below.
5. Clean the test tubes and repeat for the beetroot, tea, cranberry and turmeric indicators.
Results:
Indicator Colour in HCl (Acid) Colour in NaOH (alkali)
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