It might feel like you’re mixing potions, but this colorful experiment is definitely chemistry!
Have you heard about our Young Chefs’ Club? Members get a themed (and kid-tested) box delivered each month!
Add 1 cup water to small saucepan. Bring to boil over high heat. Turn off heat and carefully slide saucepan to cool burner.
While liquid cools, line up 3 clear drinking glasses on counter. Use sticky notes and marker to label counter in front of glasses as “only water” in front of left glass, “1 teaspoon lemon juice” in center, and “¼ cup lemon juice” on right.
(Don't read until you've finished the experiment!) Butterfly pea flowers, which are native to southeast Asia, get their brilliant blue hue from molecules called anthocyanins (“ann-though-SIGH-ah-nins”). Anthocyanins are responsible for the blue, purple, and red colors in lots of fruits and vegetables, such as red onions, blueberries, radishes, cherries, and red cabbage. Steeping the flowers in hot water transfers some of the anthocyanins to the water, turning it a deep blue color. (The flowers are inside the tea bag—see them up close in the photo at the top of this page)
When anthocyanins come into contact with acids, such as lemon juice, they change color from blue to purple to red. The more acidic their surroundings, the redder the anthocyanins become. That’s why the water mixed with ¼ cup lemon juice—the most acidic mixture—turned bright pink when you added the butterfly pea flower liquid.
Try adding butterfly pea flower tea to other drinks, such as seltzer, iced tea, and milk. Does the color change? What does that tell you?
Use the second tea bag in your box to make another batch of butterfly pea flower tea and, this time, turn it into blue ice cubes! Pour the cooled tea into an ice cube tray. Place the ice cube tray in the freezer and freeze until solid, about 2 hours.
Add butterfly pea flower ice cubes to drinks such as lemonade, seltzer, and iced tea and watch them slowly change color. (You might want to wear disposable gloves when removing the ice cubes from the tray—the butterfly pea flower liquid can stain your fingers.)