Making Indicators (experiment)

14/05/18

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.

Method:

Task one:

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 obtain a 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 tea:

Put 100ml of water into a beaker and boil.

Turn off 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.

For cranberry juice:

Pour into a beaker and leave to one side.

For the turmeric:

Mix 1 teaspoon turmeric in 100 mL cup of alcohol.

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:

Left side is Acid, right is base.

bottom left is tea in acid going up in the left side is beetroot, red cabbage, cranberry juice, and turmeric.
bottom right is tea in base going up in the right side is the same but with base.

middle is turmeric, bottom is acid top is base.

Indicator	Colour in HCl {acid}	Colour in NaOH {alkali}
Tea	didn't change{orange}	Dark violet
beetroot	peachy{red-orange-ish	yellow
Red cabbage	Red	Green
Cranberry juice	pink{light red}	Lime-green
Turmeric	Yellow	Red