Transcript Matter Chapter Twelve: The Physical Properties of Matter • 12.1 Density • 12.2 Buoyancy • 12.3 Properties of Materials.

Matter
Chapter Twelve: The Physical
Properties of Matter
• 12.1 Density
• 12.2 Buoyancy
• 12.3 Properties of Materials
Investigation 12A
Density
• How does density
determine if an object
floats or sinks?
12.1 Density
• Density describes how much mass is in a
given volume of a material.
12.1 Density
• Solids, liquids and
gases are matter, so
they all have density.
12.1 Volume
• Volume is the amount of space an object takes
up.
• The volume of a rectangular solid is found by
multiplying length times width times height.
12.1 Volume
• Measuring the
volume of liquids is
easy.
• Pour the liquid into a
marked container
called a graduated
cylinder and read
the volume.
12.1 Displacement
• You can find the
volume of an irregular
shape using a
technique called
displacement.
• Find the volume of an
irregularly shaped
object by putting it in
water and measuring
the amount of water
displaced.
12.1 Density
• The units used for
density depend
on whether the
substance is solid
or liquid.
– For liquids use
units of grams per
milliliter (g/mL)
– For solids use
density in units of
g/cm3 or kg/m3.
12.1 Density of common materials
• Density is a property of material
independent of quantity or shape.
12.1 Density of common materials
• Liquids tend to be less
dense than solids of
the same material.
• Water is an exception
to this rule.
• The density of solid
water, or ice, is less
than the density of
liquid water.
12.1 Determining Density
•
To find the density of a
material, you need to know
the mass and volume of a
solid sample of the material.
1. Mass is measured with a
balance or scale.
2. Use the displacement method
or calculate the volume.
12.1 Determining Density
•
When calculating volume, all of the
units of length involved in the
calculation must be the same.
12.1 Why density varies
Density changes for different substances
because:
1. Atoms have different masses.
2. Atoms may be “packed” tightly or loosely.