The local universal indicator is made wholly from the red leafed cabbage leaves. Ethanol or warm water is used as a solvent.
3 leaves from a red leafed cabbage are crushed in a motor, on addition of small quantities of ethanol. The resultant extract is then decanted-this will be the local indicator solution.
A strip of filter paper is then inserted into the resultant solution. This strip will serve as the universal indicator paper.
When the strip is put into various solutions, distinct colours are observed, depending on the extent of acidity or basicity of the test solutions.
With the colourations obtained, a pH chart can be designed to be used with our PH paper.
It can serve as an alternative to the simple acid base indicator in the laboratory and apply in case the laboratory has run out of commercial laboratory universal indicator.
We are interested in this project to come up with a cheaper indicator paper instead of using the normal indicator paper used in the laboratories which are at times difficult to get. An indicator is a substance which gives a definite colour in an acidic or basic solution.
Juice extract from Red leafed cabbage contains a red pigment and can be used as a pH indicator. This realisation pushed us to make a PH paper out of red cabbage juice.
The pH scale is a measure of acidity. You can buy a pH indicator paper from any biological or lab supply company, which can be used to give you an accurate measurement of the acidic or basic quality of substances you want to test. However, you can also make your own pH indicator using red leafed cabbage juice.
Statement of the problem
Can red leafed cabbage leaves be an efficient raw material for a universal indicator paper?
To develop a cheaper universal indicator paper
To construct a pH chart for the universal indicator paper.
If a strip of filter paper is dipped into a solution extract of red leafed cabbage, it can serve as a consistent universal indicator paper.
Consumes less time
Easily made from locally available resources
Gives consistent results.
It requires basic skills for operation
The solvent used might not dissolve all the pigments in red cabbage
pH of the solutions used depends on the weakness or strength of the acidity or basicity in them.
The amount of pH indicator solution obtained depends on the quantity of leaves used and the amount of ethanol added.
The intensity of the colour of the solution depends on the amount of ethanol added and the quantity leaves used.
The colours obtained in various solutions
This project can satisfactorily help schools to arrange for their Universal indicators without actually relying on a supplier. All they’ll need is the red leafed cabbage since all other requirements are readily available in schools.
In the kitchen, the indicator paper will greatly help households to know the extent of acidity or basicity of what they consume before they consume them.
Assumptions and precautions
Hot water dissolves all pigments in the red leafed cabbage.
The local indicator paper will remain consistent.
Label all the solutions to avoid confusion and contamination.
Acids are substances which react with metals, yielding hydrogen gas. With respect to protons, they are donors of protons. Their taste is sour.
Bases on the other hand have a bitter taste. Indicators are substances that show different colours in acidic or basic solutions. Universal indicators can be used to show the strength or weakness of acids and bases.
Indicators can be made locally from flower extracts, though results they give are inconsistent as the colours change overtime.
Scientific advancements have been tried to test if certain plants can give extracts that can serve as indicators.
Red leafed cabbage, Filter paper, Ammonia solution, Knife, Vinegar, Heat, Orange juice, Test tubes, Beaker, Distilled water, Dropper
- Cut the red leafed cabbage into pieces
- Using a motor and a pestle, crush the red leafed cabbage adding small amounts of ethanol as you crush.
- Decant the liquid
- Soak a filter paper in this liquid. Allow it to dry and cut the dry coloured paper into test Strips
- Dip one of the strips in HCl. Repeat the same with various solutions. Repeat the same with various solution.
- Construct a pH chart to show the acidity and basicity of the different solutions.
Distinct colours are observed as tabulated below.
Table 1. Showing colours of various solutions in local pH indicator
|Wood ash solution||Blue|
|Baking powder||Light blue|
|Soda ash||Light green|
Red leafed cabbage juice contains a pigment and can be used as a pH indicator. It is red, pink, in acids, (pH below 7), purple in neutral solutions (pH 7), and ranges from blue, green or yellow in basic solutions (pH above 7). This knowledge pushed us to make a pH paper out of red leafed cabbage juice.From the above data a pH chart can be obtained
|Sulphuric acid||1||Strong acid|
|Orange juice||6||Weak acid|
|Wood ash solution||8||Weak base|
|Baking powder||9||Weak base|
|Soda ash||10||Weak base|
|Sodium hydroxide||14||Strong base|
From 50 cm3 of the red leafed cabbage extract, 60 strips of the indicator paper can be obtained. One cabbage can give 2000 cm3 extract. It’s therefore evident that locally made indicator papers are cheap and more convenient to use
Data analysis and interpretation
From our data on testing the strength and weakness of various laboratory and household solutions, a summary can be depicted on a graph.
Conclusion and Recommendation
When using a red leafed cabbage indicator, distinct colours are observed in acidic solutions, basic solutions and neutral solutions, thus the local indicator is a simple acid base indicator that can be used as an alternative to the existing commercial indicators.
Since this is a very safe method of detecting definite colour change in acidic or basic solutions, it is our hope that this project will be taken much seriously and expanded for local use mostly in our neighbouring schools.
Link to emerging issues
With the rising economic issues, some schools might seriously be in need of universal indicators to use in their schools but lack of adequate funds limit them. Being that the local universal indicator paper is made from locally available resources, it can readily serve as a substitute to the existing expensive commercial universal indicators.