Wednesday, January 12, 2011

Molar Volume of a Gas at STP

    Since gases expand and contract depending on the pressure and temperature, we use STP (Standard Temperature and Pressure to make sure all gases are measured accurately. 1 mole of gas is to take up 22 L, at 1 atmostphere of pressure and a temerature of 0°.
   Converting from molà litres
   Ex: Calculate the volume (L) of 20mole of ammonia at STP
  20mol x      22.4L             = 448L
                  1 mole

 Converting from litresà mol
 Ex: Calculate the number of moles in 5.54 L of CO2 at STP

 5.54L x  1 mole         =  0.247 mol
               22.4 L


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