STP

STP or standard temperature and pressure,standard conditions for measurement of the properties of matter. The standard temperature is the freezing point of pure water, 0°C or 273.15K. The standard pressure is the pressure exerted by a column of mercury (symbol Hg) 760 mm high, often designated 760 mm Hg. This pressure is also called one atmosphere and is equal to 1.01325×10 ⁶ dynes per sq cm, or approximately 14.7 lb per sq in. The density (mass per volume) of a gas is usually reported as its value at STP. Properties that cannot be measured at STP are measured under other conditions; usually the values obtained are then mathematically extrapolated to their values at STP.

The Columbia Electronic Encyclopedia, 6th ed. Copyright © 2007, Columbia University Press. All rights reserved.

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