Charles's law

Charles's law (also known as the law of volumes) is an experimental <a href="/facts/Gas_laws/yfj4gtlb">gas law</a> that describes how <a href="/facts/Gas/hVVAoodV">gases</a> <a href="/facts/Thermal_expansion/BP2vjX0N">tend to expand when heated</a>. A modern statement of Charles's law is:

<blockquote>
When the <a href="/facts/Pressure/eyc37GRG">pressure</a> on a sample of a dry gas is held constant, the Kelvin <a href="/facts/Temperature/QyGe4gmj">temperature</a> and the <a href="/facts/Volume/aeAXCBUd">volume</a> will be in direct proportion.

</blockquote>
This relationship of <a href="/facts/Proportionality_(mathematics)/xDQmfh6t">direct proportion</a> can be written as:

V
        ∝
        T
      
    
    {\displaystyle V\propto T}

So this means:

V
            T
          
        
        =
        k
        ,
        
        
          or
        
        
        V
        =
        k
        T
      
    
    {\displaystyle {\frac {V}{T}}=k,\quad {\text{or}}\quad V=kT}

where:

<ul><li>V is the <a href="/facts/Volume/aeAXCBUd">volume</a> of the <a href="/facts/Gas/hVVAoodV">gas</a>,</li>
<li>T is the <a href="/facts/Temperature/QyGe4gmj">temperature</a> of the gas (measured in <a href="/facts/Kelvin/E3trzC4C">kelvins</a>), and</li>
<li>k is a <a href="/facts/Constant_(mathematics)/SxlxTWFT">constant</a> for a particular <a href="/facts/Pressure/eyc37GRG">pressure</a> and <a href="/facts/Amount_of_substance/tQVyNLCp">amount</a> of gas.</li></ul>
This law describes how a gas expands as the temperature increases; conversely, a decrease in temperature will lead to a decrease in volume. For comparing the same substance under two different sets of conditions, the law can be written as:

 
 
 
 
 
 
 V
 
 1
 
 
 
 T
 
 1
 
 
 
 
 =
 
 
 
 V
 
 2
 
 
 
 T
 
 2
 
 
 
 
 
 
 {\displaystyle {\frac {V_{1}}{T_{1}}}={\frac {V_{2}}{T_{2}}}}

The equation shows that, as absolute temperature increases, the volume of the gas also increases in proportion.

Charles's law open-in-new

Charles's law