She handled the glass like a bomb. When she filled the pycnometer with alcohol, she noticed something strange. Bubbles—tiny, stubborn bubbles—clung to the inner walls like frightened pearls.
In the fluorescent glare of a university lab, twelve-year-old Elena watched her older brother, Mateo, panic. densidad del alcohol
0.789 g/mL.
“The alcohol has microscopic air trapped inside. That air is lighter than the liquid. It’s making your volume reading wrong, but worse—it’s making your mass wrong for the space you think is full.” She handled the glass like a bomb
Elena, bored with her summer reading, peered over his elbow. “So? That’s basically the same.” In the fluorescent glare of a university lab,
Stung, he shoved the equipment toward her: a pycnometer (a fancy, expensive glass vial), a precision scale, and a vial of lab-grade ethanol. Elena read the instructions once, then twice. Mass of empty pycnometer. Mass of pycnometer plus water. Mass of pycnometer plus alcohol.
“You didn’t degas it,” she said.