In this video, we'll be exploring
the science behind butterfly pea flowers. To do this,
we'll be walking through some of our labs that use butterfly pea flowers
and explaining what occurs and why. We highly recommend that you do the labs
before watching this video. Butterfly pea flowers are actually very similar to red cabbage
and that they can be used as a pH indicator, meaning
they change color in response to pH. And that's because just like red
cabbage, butterfly, pea flowers contain anthocya
nins,
anthocyanins are actually found in a wide variety of plants like beets, blueberries,
cherries and hydrangea flowers, which are particularly cool because
we can actually influence their color by changing the pH of the soil. Blue, purple and reddish hues are often
hints that these molecules are present. These molecules are pigments
and can be different colors depending on the
pH that they are exposed to. If you feel like you need a quick review of pH,
check out our other video link to here.
Essentially, these anthocyanin molecules
interact with hydrogen ions and when they do so, they absorb
or reflect different wavelengths of light
resulting in different colors. Keep in mind,
we're only showing one molecule, but these solutions
are made up of hundreds of molecules, which is why we see a spectrum of colors
as the pH changes. Additionally, anthocyanins are actually
a large group of similar molecules, so there isn't just one exact type,
but there are hundreds of different ones. We can
think of these
anthocyanin molecules like crayons. Imagine a box of crayons of different
colors. That's pretty much what's going on
with our anthocyanin molecules, but we have a gigantic jumbo
box of hundreds of crayons. Most things will be made up of at least a few different crayons or molecules. This also helps
explain why there are some differences between red cabbage and butterfly
pea flowers. If you've used red cabbage before,
you'll know that red cabbage is purple at a neutral pH,
but but
terfly pea flowers are blue. This is because they're made of slightly
different anthocyanin molecules. Okay, let's move on to our tea that
we make with the butterfly pea flowers. Originally, the tea is blue,
and that's because the butterfly pea flowers are in a neutral solution,
which is water. When we add something acidic to the tea
like lemon juice or citric acid, the pH drops, as we add
more acid, will notice that the drink continues to get more pink,
indicating that the pH is still dropping.
In one of our labs we add and baking soda after we've added in citric acid and we'll
notice an additional color change. It becomes blue again. That's because the pH is now rising
because baking soda is basic
and has a pH of around 8. The other key thing we'll see
when adding in the baking soda is bubbles and thus creating a carbonated
fizzy texture. These bubbles are indicating
that a chemical reaction is occurring. Acids and bases like to chemically react
in a neutralization reaction. So we ha
ve the citric acid
reacting with a baking soda, which produces carbon dioxide gas,
which we notice as those bubbles. Additionally, when they react in neutral
product is formed because they're kind
of canceling each other out. So the pH is becoming closer and closer
to seven, assuming that we've combined them
in an appropriate ratio. Okay, so to recap, butterfly
pea flowers are a pH indicator because they contain anthocyanins
which change color in response to changes in pH. Originally we added ho
t boiling
water to the flowers, which is a neutral substance. When we add in something acidic
like lemon juice or citric acid, the pH drops. Then when we add a baking soda, which is basic, that pH comes back up. All right. And that's it for today. We hope you enjoyed this
episode of Bite Scized. And be sure to like
and subscribe for more videos.
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