Chemists typically make measurements under standard conditions of temperature and pressure because changes in either of these two factors will change the value of the measurement. For example we know that the volume of gases increases as temperature increases. This, in turn, will affect the density of a substance. So we often need to know under what conditions a measurement was taken. Two conditions are taken to be standards; these are known as STP and SATP. SATP is becoming the more widely used standard.
STP Standard Temperature |
Temperature = 0°C Pressure = 101.325 kPa |
STP for Thermodynamics Standard Temperature
|
Temperature = 25°C Pressure = 101 kPa |
SATP Standard Ambient Temperature |
Temperature = 25°C Pressure = 101.325 kPa |