Coins don’t float on water, except at Summer Academy, where all things are possible.
Students in Bubbleology today watched as a visiting Mad Science scientist filled clear plastic cups to the brim, and beyond, with water. Owen leaned down and peered into his cup from the side. “It looks like a hill,” he observed of the mounded water rising above the edges of the cup.
The bubbleologists were learning about surface tension of water. “It’s about bubbles and chemistry,” Owen said. (According to the USGS, surface tension could be defined as the property of the surface of a liquid that allows it to resist an external force, due to the cohesive nature of the water molecules.)
Owen watched this resistance in action, as his desk partner Derek lowered a paper clip with a silver coin onto the top of the water. “Awesome, Derek!” he cheered. “The coin floats! You didn’t break the surface tension!”
Logan explained why the coin moved immediately from the middle of the cup toward the edge. “It floats to the edge because of gravity,” he said.
The boys then watched as pepper was sprinkled onto their “hill” of water. Like the coin, the pepper spread over the top of the water, instead of sinking.
It wasn’t until a blob of liquid soap hit the water that the surface tension broke. “The soap pushed it away,” noticed Sarah.
Pepper skidded to the edges of the cup as the hydrogen in the soap molecules attached to the water and the carbon molecules reacted against it. “Carbon hates water,” the visiting scientist told the students. “A carbon molecule will try to stand up in the water – stand on its head – and break the surface tension.”
Other activities in today’s Bequiling Bubbles session included racing soap-powered boats, blowing bubbles inside of bubbles, making tetrahedron wands to create pyramid-shaped bubbles, and learning about bubble colors.
Owen was fascinated by the experiments, but was especially looking forward to the next activity. “We get to go in a bubble!” he said.
Mateo stood on a stool in the middle of a small pool of soapy water, hands to his sides, and peered through the lenses of oversized goggles. A soapy ring was pulled up around him, and suddenly he was enveloped in a life-sized bubble. The infectious smile that broke out on his face was, indeed, quite beguiling.