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 * __ Red Cabbage Juice Indicator - Practical __**

An acid and a base are two different types of chemicals. We know that an acid gives a sour taste to food, while bases give a bitter taste.
 * Introduction: **

You could also mention the pH scale here and perhaps a definition of an acid base indicator. // Red cabbage contains a pigment molecule called flavin (an anthocyanin). This water-soluble pigment is also found in apple skin, plums, poppies, cornflowers, and grapes. Indicators are able to undergo a reversible chemical change according to the pH of the environment they are in. //


 * Aim: **  The aim of this experiment was To discover, scientifically, how to tell the difference between an acidic substance, a neutral, and a basic substance using an indicator.

The convention of writing aims is to start with the word ‘To’ J


 * Hypothesis:  ** I think that we will be able to find a distinctive colour that acids turn to when red cabbage juice is added. The same should happen when cabbage juice is added to a base. If an acid turned a colour (a) and a base turned another colour (b) then any acid would turn ‘a’ and any base would turn ‘b’.

Fabulous


 * Materials:  **
 * Beaker
 * Eye dropper(Pipette)
 * Testing palate (Palette)
 * Toothpicks
 * Indicator (red cabbage juice)


 * Test Examples:  **
 * Fruit Juice
 * Salt water
 * Fish Tank Water
 * Golden Syrup
 * Molasses
 * Honey
 * Detergent
 * Soft Drink
 * Milk
 * Tap Water
 * Distilled Water
 * Conditioner
 * Conditioner(aq) Great work!
 * Yogurt

Add little drops of each substance into each circle of the palate (Palette) (don’t use the eyedropper (Pipette) for this part) and then using the eye dropper (Pipette) drop place/add a couple of drops into each of the mix. Stir slightly with a toothpick. Make sure when you do use the eye dropper (Pipette) to not touch the mix, this will contaminate the indicator. VERY GOOD
 * Method: **

Do the same with the rest of the testing examples. Remember to wear your safety glasses and lab coat! Brilliant


 * Results:  **

Test:

Indicator + Fruit Juice= Turned pink Indicator + Golden Syrup= Turned green Indicator + Salt Water= Turned purple Indicator + Molasses= Stayed black Indicator + Fish Tank water= Turned purple Indicator + Honey= Turned purple Indicator + Detergent= Turned purple Indicator + Soft Drink= Turned pink Indicator + Milk= Turned purple Indicator + Tap Water= Turned purple Indicator + Distilled Water= Turned purple Indicator + Conditioner= Turned purple Indicator + Conditioner(aq)= Turned purple Indicator + Yogurt= Turned pink

It would be even easier to read your results is they were displayed in a table J e.g.


 * Indicator added to various substances: ||  Colour change detected  ||
 * Fruit juice || Pink ||
 * Golden Syrup || Green ||
 * Etc… ||  ||


 * Discussion: **  Through the results, I am able to predict that any substance that turns purple green when red cabbage juice is added is classified as a base. If the mix turns pink then the original substance is an acid. The substances that turn green purple are neutral which means they are neither acid nor base. I found out

that: salt water, fish tank water, detergent, milk, distilled water, conditioner (aq), honey, tap water and conditioner are all bases.

While fruit juice, soft drink and yogurt are all acids, because they turned pink when red cabbage juice was added.


 * Conclusion: **  In conclusion what we have learnt from this experiment is that red cabbage juice is a very good indicator when added to chemicals to tell whether they are acids or bases. Acids turn pink when cabbage juice is added and bases turn purple green when cabbage juice is added. Chemicals that turn green purple when cabbage juice is added are neutral, so they are neither acid nor base.

Suggestions to include in discussion: Did you hear about what happened when bleach was tested? The colour change was green and then after a few seconds it became colourless. Can you explain this phenomenon?

Suggestions to include in conclusion:

Red cabbage indicator has properties that are useful in distinguishing between acids, bases and neutral substances. It does have limitations as an indicator however. When the substances being tested have a strong original colour such as molasses, cola or milk – a colour change may be difficult or impossible to detect. I would suggest that the results obtained from such solutions are not reliable.

// Very acidic solutions will turn anthocyanin a red colour. Neutral solutions result in a purplish colour. Basic solutions appear in greenish-yellow. Therefore, it is possible to determine the pH of a solution based on the colour it turns the anthocyanin pigments in red cabbage juice //. // NB: pH >12 = yellow //