Jan.11--Molar Volume of a Gas at STP

Gases expand and contract (change volume) with changes in temperature and pressure.


STP = Standard Temperature and Pressure = a standard condition to compare volume of gases

STP = 1 atmosphere of pressure and a temperature of 0 ℃

At STP, 1 mole of gas occupies 22.4 L

Conversion Factors:

22.4 L of gas / 1 mole of gas  OR  1 mole of gas / 22.4 L of gas

Ex. Calculate the volume occupied by 3.4 g of ammonia at STP.

   NOTE: Ammonia = NH₃

     NH₃ = 14.0 + 1.0 x 3 = 17.0 g / mol

3.4 g x (1 mole / 17.0 g) = 0.2 moles

(22.4 L / 1 mole) x 0.2 mol = 4.5 L