A Kilogram of Each
A 1.00 kg bar of gold is about half the size of a deck of cards. A 1.00 kg block of polystyrene foam would fill a large backpack.
They weigh exactly the same. What is different, and which one is heavier?
Page 1
Science · Chemistry
Chapter 1: Matter and Measurement
A property that does not depend on how much you have.
A 1.00 kg bar of gold is about half the size of a deck of cards. A 1.00 kg block of polystyrene foam would fill a large backpack.
They weigh exactly the same. What is different, and which one is heavier?
Make your guess to turn the page.
Still to come: 10 pages · Lab · Words to Know · What We Learned · 4 questions · Explain It in Writing · Open Questions
The idea this lesson is working on — Students merge heavy and dense, so a big, heavy object sounds dense and a small one does not. The book sets a kilogram of gold beside a kilogram of foam, halves a gold bar, and runs a lab where no column needs the size of the sample. Ask: would cutting the sample in half change this number? The idea to reach is that density is intensive and mass is extensive, and only the intensive one identifies.
Density identifies materials, within limits — Values are at about 20 °C: gold 19.32, tungsten 19.25, copper 8.96, nickel 8.91, iron 7.87, aluminum 2.70 g/cm³; polystyrene foam varies from about 0.01 to 0.05, while solid polystyrene is about 1.05. Ice at 0 °C is 0.917 g/cm³, about 8% less dense than water; the often-quoted 9% is the increase in volume on freezing. Tungsten-cored counterfeit bars have been reported in the gold trade.