Chemical Engineering - Chemical Engineering Thermodynamics - Discussion

Standard temperature and pressure (STP) and Normal temperature and pressure (NTP) are two sets of reference conditions that are commonly used in science and engineering.

The main difference between STP and NTP is the temperature and pressure values that they represent.

STP is defined as a temperature of 0 degrees Celsius (273.15 K) and a pressure of 1 atmosphere (101.325 kPa or 760 mmHg). STP is often used as a reference for measuring gas volumes and is commonly used in fields such as chemistry and physics.

NTP, on the other hand, is defined as a temperature of 20 degrees Celsius (293.15 K) and a pressure of 1 atmosphere (101.325 kPa or 760 mmHg). NTP is often used as a reference for measuring gas flow rates and is commonly used in fields such as engineering and environmental science.

It is important to note that STP and NTP are not interchangeable and their specific values should be used according to the context and application of the measurement being made.

The S.T.P. conditions according to IUPAC is;
Standard Pressure = 1 atm or 750 mm Hg.
Standard temperature = 273.15 K or 0°C.

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, 0.987 atm, 1 bar).

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, 0.987 atm).