Red cabbage litmus paper

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THE SCIENCE LAB

Make & Do Activity Kit

500 Harris St Ultimo

PO Box K346 Haymarket NSW 1238

Australia

Tel: 02 6217 0111

http://play.powerhousemuseum.com

This work is licensed under the Creative

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Homemade litmus paperLitmus paper is used in many simple experiments to test

or PH balance. When dipped into dierent substances itwill turn dierent colour according to how acidic or basic

it is. It is sometimes called acid-indicator paper.

Time:1+ hrs

Difculty:

Hints: Remember that some household substancescan be harmul to eyes and skin so this is an activity

to do with adult permission and supervision.

Adult or supervised step:

Chop some red cabbage

leaves into small pieces and

place in a saucepan. Pour

water over the cabbage and

simmer or 20 minutes.

1.

To prepare your test

substances place each

separately in a dish or cup.

Powdered substances need

to be mixed with a little

water. Label each clearly.

2.

When the red cabbage

mixture has cooled, place

the seive over the large

bowl, strain the cabbage

and collecting the liquid.

Allow to cool until warm.

3.

Soak each strip into the

cabbage sollution and lay it

onto the old tea towel to dry.

4.

Arrange labelled test dishes

in a row on scrap paper.

Place a litmus strip in ront

o each test dish. Dip each

into a bowl or 5 seconds.

5.

Watch the colours change

on the litmus papers.

Compare them to the ph

chart on page 3. Choose

more substances to test

rom our suggestion list.

6.

a chopping board

a knie

a saucepan

1 litre o water 1 dish or cup or

each test substance

(suggested list below)

Pen and paper

large plastic bowl

a seive

blotting or watercolourpaper (cut into10cm x

3cm strips)

old tea towel & paper

What you will need:

500 Harris st. Ultimo

PO Box K346 Haymarket NSW 1238Australia Tel: 02 9217 0111


Creative Commons Licence for use of this work

This work is licensed under a Creative Commons Attribution-NonCommercial 3.0 Australia Licence (CC BY-NC 3.0 AU)

http://creativecommons.org/licenses/by-nc/3.0/au/

Household substances to test: lemon juice

shampoo

orange juice

white vinegar laundry detergent or

powder

bicarb soda

tartaric acid or citric

acid

milk

egg whites toothpaste

lemonade

tap water


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Australia

Tel: 02 6217 0111





THE SCIENCE LAB


Homemade litmus paper

What else can i do?

Activity 1: Record your results.

Recording test results is important or observing

and comparing outcomes o dierent tests. It allows

you to nd answers to questions and come to

conclusions.

You have used strips o litmus paper to testsubstances around the house. Now create a result

table to sort your ndings into acids, neutrals and

bases.

Use the PH scale on the next page to order your test

substances into acid, neutral and base by matching

up the colours.

Activity 2: Create decorating craft paper.

This is a simple variation and results in beautiully

colored paper that can be used or art projects likecollages. Here is an example we prepared using a

litmus paper painted with lemon juice, baking soda

sollution and white vinegar.

Acid, neutral or base?

Whats going on?

Chemicals can be either an acid,

a neutral or a base. In order totest i something is an acid or a base we can use an

indicator. An indicator will change in colour when it

goes rom a neutral condition to an acidic or basic

condition and can tell us the pH o dierent things.

Red cabbage contains a natural pigment molecule

called favin which changes colour when it comes

into contact with acids and bases. We call this

chemical a pH indicator.

The indicator changes rom purple to bright pink in

acids to blue or green in bases. Using the changingcolours we can create a pH scale which numbers 1

to 14.

When a chemical has a pH o 7 it is neither an

acid or a base and it is called neutral. Water is

considered neutral. It is important to note that the

indicator itsel might not be neutral.

Lemon juice and vinegar are both acid so they will

turn the litmus paper pink. Baking soda turns a

green/blue colour indicating a base is present.








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Australia

Tel: 02 6217 0111





THE SCIENCE LAB


Homemade litmus paper







Red cabbage litmus paper

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