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Chemistry, Everyday science experiments, Uncategorized

Magic Mondays: Surface Tension and Basilisk Venom

A few years ago, I made a potions kit as a gift for a young Harry Potter fan. I had a blast coming up with different science experiments that could be done with ingredients from the grocery store and renaming them to create my own magical illusions. Well someone asked if I could share these tricks, so I’m going to attempt that over the next several weeks. I realize that with Christmas looming someone might want faster access than one per week so stay tuned.

This week, we’re using a hydrophobic material and surface tension to test some Basilisk Venom.

Video of Baslisk venom test

Actual Recipe

Black Pepper

Liquid Dish Soap


(Optional) Toothpick

Potion Recipe

Spiders Eggs

Basilisk Venom


(Optional) Bowtruckle Hair


Fill a small bowl with water

Sprinkle the spider eggs on the water

Carefully drop one drop of Basilisk venom into the centre of the spider eggs

If it is true Basilisk venom, the spider eggs will flee the moment the venom touches the water.

The science behind the magic:

Pepper is hydrophobic, which means that it isn’t attracted to water: the pepper would rather be connected to itself than to the water.

Meanwhile, the water molecules maintain surface tension because of the attraction between the molecules. This is the same property that allows certain insects to walk on water and allows a drop of water to keep a round-ish shape (its minimizing the surface area).

These two properties mean that most of the pepper will stay floating on top of the water.

When you add the dish soap to the water it disrupts the surface tension of the water, which is why it helps to clean dishes. But the water is trying to avoid being separated, so it pulls back away from the soap and it pulls the pepper with it.

Flecks of black pepper floating in water. The pepper forms a ring around the outer edge of the bowl.

“Spider eggs” after exposure to “Basilisk venom”

About Tai Munro

I am passionate about making science, sustainability, and sport accessible through engaging information and activities.


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