A Not So Serious Experiment Report

Red Cabbage as Kitchen pH Indicator

As mentioned in our discussion about acid-base reaction, many natural materials found in kitchens can be used as pH indicators. In our experiment tonight, we will be using a common cooking ingredient, red cabbage.

Materials Required:

Red cabbage	Plastic Cups	Stain Remover	carbonated or seltzer water
Vinegar	Spoons	drain cleaner or lye	muriatic acid
Sodium bicarbonate	knife	baking soda	Water
Bleach	Water Kettle

Snapshots of All Materials

A. Preparing Red Cabbage Extract

First, we had to tear off leaves from the cabbage and then, cut them into smaller pieces.

Then, we boiled the red cabbage leaves in distilled water using water kettle. Please don’t be surprised, this is because we are not allowed to use stoves in our hostels. Once the water boiled, we turned down the heat to boil it gently.

When the distilled water turned purple, we then took the cabbage soup out and let it cool down. In meantime, we then went a few rounds of futsal games downstairs. When we came back, we then filter the cabbage pieces out using the crudest method as shown below. We would only need the cabbage juice as our pH indicators. Be careful that cabbage juice can really stain your shirt. So, do necessary precautions which we did not.

Testing pH Values of Household Items

Testing pH values of items using red cabbage juice is super easy. Just simply mix them and you will be fine. Since our red cabbage juice was made highly concentrated, the reaction went on really fast. Just a blink of eyes, the color changed. If the item tested is acidic, the cabbage juice will turn pink and sometimes red. On the other hand, if it is basic, the cabbage juice will turn green. In a neutral solution, however, cabbage juice remains reddish-purple.

Our Results through Pictures

Sodium Bicarbonate

Final Color of Cabbage Juice: Green

Interpretation: Sodium Bicarbonate is basic.

Vinegar

Final Color of Cabbage Juice: Pale Red

Interpretation: Vinegar is acidic

Stain Remover (containing acid)

Final Color of Cabbage Juice: Pale Red

Interpretation: Stain remover is acidic

Bleach

So What Is Behind This Experiment?

Through boiling, we had extracted the pigment molecules called anthocyanins which change color with the pH of their surroundings. This simple experiment only shows the rough acid-base range but not the exact pH value. It is just as simple as this. So, do try out this simple pH indicator at home like what we did!

                                                                                                                                                                  

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