A spooky chemistry lesson

Oceanside High School chemistry teachers treated students to a few Halloween-themed tricks to demonstrate principles such as sublimation (going from solid to gas without the liquid phase), what a catalyst does, the properties of acids and bases and how oxygen makes a flame burn brighter.

Teacher Danielle Block asked four students — Andrew Kear, Natasha Alford, Jacob Worth and Mayla Campagna — to assist in an experiment she called Witches Brew. Each student was given a beaker of colorless liquid and lines to recite from a poem called “The Witches’ Potion,” while pouring the liquids into other beakers according to Block’s instructions. Mixing the first two colorless liquids created a pink liquid, but pouring it back into a beaker filled with colorless liquid made the pink tint instantly disappear.  Later, Block invited the class to discuss how the properties of a base (like ammonia) turn the chemical, phenolphthalein, pink, while an acid (like vinegar) renders it colorless.

The “puking pumpkin” used hydrogen peroxide, potassium iodide as a catalyst (something that speeds up a reaction), a squirt of dish detergent for bubbles and food coloring. The potassium iodide caused the hydrogen peroxide to break down faster than it normally would, releasing

oxygen, which propelled the contents out of the pumpkin’s carved mouth.