Chapter 6 - CCRI Faculty Web

Chapter 6
Behavior of Gases
When substances are in the Gas Phase, there is a unique
All substances while in the gas phase behave the same.
We can look at a few of these.
• Molecules are relatively far apart and therefore they
don’t attract each other.
• Molecules are in constant motion, moving faster at
higher temperatures.
• Gases exert pressure when molecules hit the walls of
their container.
• Gases fill their containers because they don’t attract
each other.
• Gases obey the Gas Laws. Two of these are:
 Boyle’s Law - 1662
- named after Robert Boyle (the same person who
gave us the modern definition of an element)
Charles’ Law – French Physicist – Jacques
Charles - 1787
Boyle’s law: At
constant temperature,
the volume of a gas is
inversely proportional
to its pressure.
© 2010 Pearson Prentice Hall,
Charles’s law: At
constant pressure, the
volume of a gas is
directly proportional to
its absolute
© 2010 Pearson Prentice Hall,
When doing gas law calculations, we need to use a
different temperature scale than Celsius or Fahrenheit. It
is called the Absolute Temperature scale or Kelvin
Temperature scale. 0 on the Absolute scale is the lowest
possible temperature.
Absolute Temperature is designated kelvins or K.
Named after William Thomson – Lord Kelvin - 1848
Mathematically: K = °C + 273
Charles’s Law
At liquid nitrogen
temp: -196°C or 77 K
Same balloon at
Room Temp
© 2010 Pearson Prentice Hall,

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