DIY pH Indicator - Petrosains

DIY pH Indicator

Starting from 18 March 2020, our country has been under a series of orders called the “Movement Control Order”. It means that we should stay at home and only go out of the house to get our daily essential items.

Starting from 18 March 2020, our country has been under a series of orders called the
"Movement Control Order". It means that we should stay at home and only go out of the house
to get our daily essential items.

After hearing about the announcement, I was saddened as my plans for the year were all
disrupted. Nevertheless, that did not stop me from doing interesting things that are related to
STEM to boost my knowledge and fill up my spare time by doing something useful and

Not long after, I was assigned to prepare my own pH indicator using natural ingredients and test
it on items in our daily life such as soapy water and lemon juice in order to determine whether
they are acidic, alkaline or neutral. Upon getting the task, I set off to do my research to decide
what is the best ingredient to prepare my pH indicator. Oh! For your information pH means
potential of hydrogen. As I was browsing the internet, I saw a lot of people using purple cabbage
to make the pH indicator but I decided to make something special to surprise my friends. After a
couple of research, I found out that most of the foods that contain colours such as red, pink,
green or purple are suitable to act as a pH indicator. This is because these water-soluble pigments
contain a molecule called "Anthocyanin" that will change its colour according to different pH

I decided to use red apple peels to make my pH indicator as I already had apples in my fridge.
After doing ample research, I set off to conduct the experiment with full excitement. The steps

are quite easy as you just have to peel a few apples and boil the peels for some time and ta-da
you just got yourself a homemade pH indicator.

After the cooling process, I prepared various ingredients to be tested to determine the pH level
and place them in medicine cups because it is easier to observe the colour changes. In order to
obtain results that are more accurate, I also placed a piece of A3 size paper under the medicine
cups so that I could observe the true colour of the test. Afterwards, I slowly dripped the pH
indicator solution into the chemical substance and recorded the colour changes of the substance.

After conducting the test, I realized that chemical substances that are acidic will turn out to be
pinkish-red while alkaline substances will appear to be greenish while neutral substances will
have the same colour as the pH indicator solution. From this experiment, I learnt that milk is
actually an acidic substance while the sewage pipe cleaner solution is an alkaline substance. All
the while I thought that the sewage pipe cleaner solution is an acidic substance but this
experiment proved me wrong.

Throughout this experiment I used distilled water because distilled water does not contain any
impurities and microorganisms that will affect my experiment outcome. From this experiment, I
discovered the pH level of ingredients used in our daily lives. I even get to understand and
appreciate the importance of the use of chemicals in daily life. This activity definitely made my
days at home more interesting as it was hands-on which made the learning process fun.

In conclusion, this experiment was really fun as it can be conducted with basic household items.
I hope that there will be more such activities carried out to make learning more fun. Experiments
and observations can make us understand and remember the subject better. I would highly
recommend this experiment to science lovers to boost their interest in this subject.

Prepared by Chen Pei Wei, Guest Blogger