Experiential Learning of Acidity in Science through Experimentation

Butterfly Pea Flower - its edible blue dye can test for pH (acidity)!
19Aug 2020 by Principal

By Mr Chen

In iMatter, Science is a passion among our tutors and we work to inculcate it in our students. Perhaps sounding cliched, we wholeheartedly believe that Science is Everywhere.

Science is not a subject to be studied solely by theory. Book knowledge has to be reinforced and nurtured through hands-on experimentation and observation. If the Science student has the opportunity to conduct field work, more power to him!

The Trouble with COVID-19

Unfortunately, the past few months of the COVID-19 situation has somewhat dampened the experiential aspect of Science. Schools and their laboratories were closed. Public venues e.g. Science Centre, Marina Barrage were likewise closed to the public. A student interested in biology, hydrology or ecology could not even visit our parks and nature reserves to observe Science in real life. (At this point of time, visits to the above public places are still limited to a certain number or group size.)

Can you check acidity with a weed?

Upon reopening our premises in Phase 2 of the easing of Circuit Breaker measures, we picked up where we left by working on a simple experiment involving the concept of acidity. In this experiment, we used a weed found locally (used to be a lot more common in the old days) – the Butterfly Pea Flower (Clitoria ternatea).

Being a food person (who isn’t?), I knew about this plant for the edible blue dye extracted from its flowers. The dye is used to to imbue a blue coloration to glutinous rice with mango (a Thai dish), as well as the Nyonya and Malay Kuih well loved by me since a kid. I went on to learn about its medicinal benefits and how it is made into the Thai Blue Tea (a supposedly favourite beverage in Thailand).

But do you know that the colour of the dye can be adjusted to a purplish shade? Yes, it is done by adjusting its pH which is a measure of acidity. (Actually, pH and acidity are not exactly the same in Science but we shall not dwell on this for now.) Of course, this also means that we can create Thai Purple Tea if we want!

I will now leave you to enjoy the photos and the captions below!

Figure: The original blue of Butterfly Pea Flower
Figure: Increasing its acidity with a few drops of Lime or Lemon turns it purplish
Figure: Different shades of purple can be obtained by adding different amounts of an acid such as Lime or Lemon
Figure: The changing acidity of the “tea” can be measured by indicator paper.

If you are interested in our Programmes, you can check out our Primary Science Tuition Class, Lower Secondary Science Tuition Class or Chemistry Tuition Class and Enrichment Programmes.