1. Fluids and Density
Ch 7.2

2. What is a fluid? A fluid is any form of matter that can FLOW Examples:
Lava, water, syrup, gases...
Fluids include liquid and gases but NOT solids

3. Density of Fluids & Solids
What do we mean when we say the traffic was dense? Or the trees in the forest are dense?
Density = the mass of a given volume
How closely packed together particles are in a material

4. Float or Sink??? Objects that are less dense will float
Denser objects sink!
Most substances are denser in their solid form than their liquid form.
Exception: water (ice is less dense! So ice floats...)

5. The Density of ICE
Since solid water (ice) is less dense, it floats on liquid water.
This is why glaciers don’t sink!
It also allows fish and other life in lakes to stay alive in cold winters....

6. Calculating Density To calculate density we use the formula:
D = mass (g)
volume (mL)
= m V

7. Volume Volume is measured in millilitres (mL)
1 mL = 1 cm3 (cubic centimeters)
LIQUIDS -> Use mL
SOLIDS -> Use cm3

8. We could measure your volume this way too...
Displacement
Sometimes we have to find the volume of oddly shaped objects....
We can use displacement (putting the objects in water and measuring the change in volume)
We could measure your volume this way too...

9. Practice problems Turn to page 265 and the Practice Problems #1-3
What is the density of a 2 cm3 sugar cube that has a mass of 3.18g?
A 3mL sample of oil has a mass of 2.64 g. What is the density of the oil?
The mass of 1 cm3 of lead is 11.34g. The mass of 1 cm3 of iron is 7.87 g. Which solid has greater density?

10. Answers
g/cm3
2. .88g/ml
3. lead