|  |  |  |  |  |  |  |  |  |  |  | 
   
    | • | Put a lid on a
    container filled with a liquid so have 
 | 
   
    |  | 
   
    |  | closed system. 
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    |  | 
   
    | • | Find some of the
    molecules in the liquid phase 
 |  | 
   
    |  | 
   
    |  | have enough KE to
    escape from the surface of the 
 |  | 
   
    |  | 
   
    |  | liquid and form a
    vapor phase. 
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    |  | 
   
    | • | At the same time
    some of the gas molecules in the 
 |  | 
   
    |  | 
   
    |  | vapor phase fall
    back into the liquid. 
 |  | 
   
    |  | 
   
    | • | evaporation 
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    |  |  | 
   
    |  | 
   
    | • | Liquid                          gas 
 |  | 
   
    |  | 
   
    | • | condensation 
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    |  |  |