1. Chapter 3: Measurement: Density

2. Objectives Relate floating to differences in density
Calculate the density of a material from experimental data
Describe how density varies with temperature

3. Density Density ratio of the mass of an object to its volume
intensive property that depends on the type of material (composition), not on the amount

4. Constant mass
When mass is constant…
Denser material has less volume

5. Constant volume When volume is constant… Denser material has more mass
Aluminum
2.70 g/cm3
Gold
19.3 g/cm3

6. Density and floating
Lower density substances float on top higher density substances
Ice is less dense than liquid water

7. Changing density & temperature
Experiments show that the volume of most substances increases as the temperature increases
This means the density of most substances will decrease as the temperature increases
Example: hot air rises (floats) over cold air

8. Practice calculating density
Question 1
A copper penny has a mass of 3.1 g and a volume of 0.35 cm3. What is the density of copper?

9. Practice calculating density
Answer 1
Given
Mass = 3.1 g
Volume = 0.35 cm3
Density = ?
Work
density = 8.9 g/cm3 (rounded to 2 sigfigs)