Standard Temperature and Pressure:
-Molar volume of a Gas at STP. Gases expand and contract (change volume) with changes in temperature and pressure. We have a Standard cordition to compare volume of gases called STP.
-In chemistry, IUPAC established standard temperature and pressure (informally abbreviated as STP) as a temperature of 273.15 K (0 °C, 32 °F) and an absolute pressure of 100 kPa (14.504 psi, 0.986 atm), An unofficial, but commonly used standard is standard ambient temperature and pressure (SATP) as a temperature of 298.15 K (25 °C, 77 °F) and an absolute pressure of 100 kPa (14.504 psi, 0.986 atm).
- At STP 1 mole of gas occupies 22.4L
Thus we can create the conversion factors:
22.4L of gas/ 1 mole of gas OR 1 mole of gas/ 22.4L of gas
Example: calculate the volume occupied by 3.4 g of ammonia at STP.
First step: Molar mass of ammonia(NH3)
(1x14)+(3x1)=17g/mol
Step two: Moles of ammonia
3,4g of NH3/ 17g= 0.20 moles of NH4
Step three: Molar volume
0.2 moles x 22.4L= 4.5 L
(volume occupied by 3,4 g of ammonia at STP=4.5L)
http://www.gaston.k12.nc.us/schools/highland/faculty/blpadgett/Course%20Outline%20and%20Syllabus/CH%2011%20Molar%20Volume%20Worksheet.pdf if you want do more example!!!
