Mateo stared at her. “How do you know that?”
She carefully tilted the pycnometer, letting the bubbles escape one by one, then topped it off. She weighed it, did the math on a napkin, and slid it back. densidad del alcohol
That night, over celebratory pizza, their father asked what she wanted to be when she grew up. Mateo stared at her
“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.” That night, over celebratory pizza, their father asked
“You did that without even using a formula,” Mateo whispered.
That was the magic word: meniscus . The curved smile of liquid in a graduated cylinder. Elena had seen her mother check the oil in the car using the same principle.
“I used a formula,” Elena said, closing the ethanol vial. “I just didn’t need a calculator. The alcohol wants to be 0.789. The air just got in the way.”