Final answer:
Standard Temperature and Pressure (STP) is defined as 273.15 Kelvin and typically 1 atmosphere (atm) of pressure, which is important for comparing the properties of different gases.
Step-by-step explanation:
Standard Temperature and Pressure (STP) refers to a specific set of conditions widely used as reference points for the study of gases and their physical properties. Standard temperature is defined as 273.15 Kelvin, which is equivalent to 0°C, and standard pressure is typically taken as 1 atmosphere (atm). Originally, STP was defined with a pressure of 0.986 atm; however, for simplicity and modern usage, the standard is usually rounded to 1 atm. It's important to recognize that defining STP allows scientists and students to directly compare the properties of different gases under the same reference conditions. For instance, at STP, one mole of an ideal gas occupies a volume of about 22.4 liters, a value known as the standard molar volume.