Properties of Gases

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Properties of Gases

• The volume of a gas is the same as the volume of
  its container.

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Properties of Gases

• The volume of a gas is the same as the volume of
  its container.
• This is because gases fill the space available.

3
Measuring gas temperature

• Temperature is a measure of the energy of motion
  of the particles.

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Measuring gas temperature

• Temperature is a measure of the energy of motion
  of the particles.
• The faster the particles move, the greater the
  energy and higher the temperature.

5
A thermometer

• is like a speedometer for molecules.

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How fast do gas particles travel?
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How fast do gas particles travel?

• About 500 meters/second at room temperature.

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How fast do gas particles travel?

• About 500 meters/second at room temperature.
• They collide constantly with each other and the
  walls of their container.

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The outward push is called pressure.
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The outward push is called pressure.

• Pressure Force/Area

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The outward push is called pressure.

• Pressure Force/Area
• The USA measures pressure as PSI

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The outward push is called pressure.

• Pressure Force/Area
• The USA measures pressure as PSI (pounds per
  square inch).

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The outward push is called pressure.

• Pressure Force/Area
• The USA measures pressure as PSI (pounds per
  square inch).
• The SI measure is kPa (kilopascals).

14
In an inflated ball,

• there are more particles inside than outside.

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In an inflated ball,

• there are more particles inside than outside, so
  the pressure inside is greater.

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Your chance for fame fortune!

• If you increased the pressure on the outside of
  the ball, would the ball change in volume?

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If you said

• the ball would get smaller . . .

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You could have been famous!
If you said

• the ball would get smaller . . .

19
Boyles Law
This is called

• When the gas pressure increases, the volume
  decreases.
• When the pressure decreases, the volume
  increases.

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Boyles Law
Least pressure
Most pressure
Most volume
Least volume
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A second chance at fame . .

• If you put a balloon in the refrigerator, would
  it stay the same size, increase in size, or
  decrease in size?

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And the answer is . . .

• It would decrease in size?

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Charless Law
This is called

• When the temperature of a gas is increased, its
  volume increases.
• When the temperature decreases, volume decreases.

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Charless Law
Low temperature
High temperature
Low volume
High volume
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Charless Law
Low temperature
High temperature
Low volume
High volume
If you double the temperature, you also double
the volume.
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Relationship between pressure and temperature.
Low pressure
High pressure
Low temperature (slow particle movement)
High temperature (fast particle movement)
27
Which box below would have the least mass, A or
B?
Low pressure
High pressure
Low temperature A
High temperature B
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The answer is NEITHER. The mass would be the
same! WHY?
Low pressure
High pressure
Low temperature A
High temperature B
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The amount of matter is unchanged.
Low pressure
High pressure
Low temperature A
High temperature B
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But Ive always heard that hot air rises, so
wouldnt B be lighter?
Low pressure
High pressure
Low temperature A
High temperature B
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It would be more accurate to say that less dense
air rises.
Low pressure
High pressure
Low temperature A
High temperature B
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And the density of A and B is the same.
Low pressure
High pressure
Low temperature A
High temperature B
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So how could you make box B gas less dense than A?
Low pressure
High pressure
Low temperature A
High temperature B
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When you figure that out, youll know the real
secret behind why a hot air balloon floats!
Low pressure
High pressure
Low temperature
High temperature
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