Hey there!
The acronym STP in chemistry stands for Standard Temperature and Pressure. At STP, the temperature will be 273.15 Kelvin (0°C or 32°F) and one mole of gas will occupy 22.4 liters of volume. Standard pressure is set at 1 atm. STP measurements are often used to solve the ideal gas formula (PV = nRT).
Hope this helped you out! :-)
