In chemistry, standard temperature and pressure (STP) are reference conditions used to compare the properties of gases. STP is defined as a temperature of 0 degrees Celsius (273.15 Kelvin) and a pressure of 1 atmosphere (101.325 kilopascals). The International Union of Pure and Applied Chemistry (IUPAC) used to define STP as 0 ᵒC (273.15 K, or 32 ᵒF) and 1 atm (101.325 kPa = 760 Torr). However, this definition is now obsolete. Since 1982, STP has been defined as a temperature of 273.15 K (0 °C, 32 °F) and an absolute pressure of exactly 105 Pa (100 kPa, 1 bar). In the chemical process... Show more

In chemistry, standard temperature and pressure (STP) are reference conditions used to compare the properties of gases. STP is defined as a temperature of 0 degrees Celsius (273.15 Kelvin) and a pressure of 1 atmosphere (101.325 kilopascals). The International Union of Pure and Applied Chemistry (IUPAC) used to define STP as 0 ᵒC (273.15 K, or 32 ᵒF) and 1 atm (101.325 kPa = 760 Torr).

However, this definition is now obsolete. Since 1982, STP has been defined as a temperature of 273.15 K (0 °C, 32 °F) and an absolute pressure of exactly 105 Pa (100 kPa, 1 bar). In the chemical process industry, thermocouples, also called thermoelectric couples, are the most common type of temperature sensors. They use voltage to measure differences in temperature. To record pressure and pressure change during electronic pressure measuring, a sensor is needed. This sensor records the pressure and pressure change and converts the values repeatedly into an electrical signal.

Temperature and pressure have an inverse relationship. This means that when temperature is high, pressure is low, and when temperature is low, pressure is high.

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