Physical Properties of Matter

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Chapter 2-2

• Physical Properties of Matter

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Physical Properties

• A physical property of matter can be observed or
  measured without changing the matters identity.
• Some examples of physical properties are state
  (phase), density, solubility, ductility,
  malleability, magnetism, and ability to conduct
  electricity.

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Physical Properties

• State (or phase) is the physical form in which a
  substance exists.
• The states of matter are solid, liquid, gas, or
  plasma.
• Density is the mass per unit volume of a
  substance.
• Solubility is the ability of a substance to
  dissolve in another substance.

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Physical Properties

• Ductility is the ability of a substance to be
  pulled into wires.
• Malleability is the ability of a substance to be
  rolled or pounded into thin sheets.

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Ductility Malleability
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Density

• Density is a physical property that describes the
  relationship between mass and volume.
• Density is the amount of matter in a given space,
  or volume.
• A golf ball and table-tennis (ping-pong) ball
  have similar volumes but the golf ball is denser
  because it has a greater mass.

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Density

• In Figure 4, page 46, why do you think maple
  syrup is on the bottom of the six liquids? Why
  do you think corn oil is on the top?
• The denser liquids sink to the bottom of the
  flask. The less dense liquids rise to the top.
• The order in which the layers separate shows the
  order of increasing density.

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Density
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Density

• Knowing the density of a substance will tell you
  if the substance will float or sink in water.
• The density of water (at 4C) is 1.00 g/cm3.
• If an object is less dense than water it will
  float in water.
• If the object is more dense than water it will
  sink.

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Density
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Solving for Density

• Density (D) is found by dividing mass (m) by
  volume (V).
• Units for density consist of a mass unit divided
  by a volume unit.
• Common units for density are g/cm3, g/mL, kg/m3,
  and kg/L.

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Using Density to ID Substances

• Each substance has a density that differs from
  the densities of other substances.
• The density of a substance is always the same at
  a given temperature and pressure.
• What is the density of Helium gas?
• 0.00001663 g/cm3
• Write this in scientific notation.
• 1.663 x 10-5 g/cm3

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Using Density

• What is the density of Mercury (the only liquid
  metal at room temperature)?
• 13.55 g/cm3
• Read the Math Focus section of page 47. Try the
  three sample questions.

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Using Density

• What happens to the density of an object if the
  object is cut in half? Why?
• The density remains the same because cutting the
  object in half will divide the mass volume by
  the same amount. Also, the density of a
  substance remains the same no matter what size it
  is. All matter has its own unique density.

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Interesting Density Fact

• The density of a fresh egg is about 1.2 g/mL, and
  the density of a spoiled egg is about 0.9 g/mL.
  The density of the egg decreases as it ages
  because as it spoils, it loses water through the
  tiny pores in the shell.
• What would happen to a fresh egg if placed in a
  beaker of water? What would happen to a spoiled
  egg?

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Physical Changes

• A physical change is a change that affects one or
  more physical properties of a substance.
• Freezing water to make ice or sanding a piece of
  wood are examples of physical changes.
• Physical changes do not change the identity of
  the matter involved, only some of the physical
  properties.

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Phase Changes are Physical Changes