Stp Stands For In Chemistry

What is standard temperature and pressure (STP)?

Standard temperature and force per unit area (STP) refers to the nominal conditions in the atmosphere at sea level. These atmospheric condition are 0 degrees Celsius and 1 atmosphere (atm) of pressure. The STP value is important to physicists, chemists, engineers, pilots and navigators, among others.

Standard conditions for temperature (T) and pressure level (P) refers to a specific pressure and temperature used to report on the backdrop of matter. STP values are commonly used in experiments involving gases.

In the past, the International Marriage of Pure and Applied Chemistry (IUPAC) defined STP as the post-obit:

Temperature: 0 degrees Celsius (273.15 degrees Kelvin or 32 degrees Fahrenheit)
Force per unit area: 1 atm (101.325 kilopascal or 760 Torr).

This definition is at present discontinued. Notwithstanding, these conditions are even so commonly used to define the volume (V) term normal cubic meter. Since 1982, IUPAC has applied a more stringent definition of STP:

Temperature: 0 degrees Celsius (273.15 degrees Kelvin or 32 degrees Fahrenheit)
Accented force per unit area: 100,000 pascals or 10⁵ Pa (ane bar, 14.5 pounds per square inch, 0.98692 atm).

Thus, standard temperature is defined as 0 degrees Celsius, which translates to 32 degrees Fahrenheit or 273.15 degrees Kelvin. This is essentially the freezing point of pure water at bounding main level in air at standard pressure level. The National Institute of Standards and Applied science defines STP differently equally absolute pressure of 1 atm (101.325 kPa, xiv.696 psi) and 20 degrees Celsius (293.fifteen degrees Kelvin, 68 degrees Fahrenheit).

The need for standard temperature and pressure

Both temperature and air pressure vary from ane place to another. To exam, compare and document chemical and physical processes where temperature and pressure play a role, including information centers or anywhere computers are used, a standard reference of both is required. Certain properties of matter also vary with changes in temperature or pressure. These include the following:

density
viscosity
melting signal
humid point

A reference value of temperature and pressure accommodates comparisons and measurements of processes. It also enables meliorate understanding and comparison of diverse properties of matter. STP provides such a reference.

Photo of a Google data center in Douglas County, Georgia. — It tin can be challenging to regulate temperature and humidity in big data centers like this Google information heart in Douglas Canton, Georgia.

STP weather are of import to calculate and express fluid flow rates and the volumes of liquids and gases when standard country conditions are applied. These backdrop are also highly dependent on temperature and pressure level conditions and changes. Adopting and stating standard conditions enable like experiments to occur in similar laboratory conditions and to generate similar and comparable results. It also makes it easier to compare dissimilar measurements for gases, such as the moles (mol) of gas in a given volume.

Standard temperature and pressure for gases

STP values are near normally specified for gases because their characteristics tend to change dramatically with changes in temperature and/or pressure level.

STP effect on oxygen

For example, at STP, the volume of oxygen (O₂) in 1 milliliter of atmospheric air is 210 microliters (μl). One micromole (μmol) of gas occupies 22.414 μl, and so at 210, this volume of O₂ contains the following:

210 / 22.414 = 9.37 μmol

At any other non-STP temperature, the amount of oxygen tin can be obtained by multiplying it by 273 / (273 + T). Thus at 20 degrees Celsius, the respective value is the following:

= 9.37 ten (273 / 273 + 20)
= viii.73 μmol

STP issue on carbon dioxide

At STP, carbon dioxide (CO₂) usually behaves equally a gas. When information technology is frozen, it behaves as a solid called dry ice. If the temperature and pressure level are both increased from STP above the disquisitional point, CO₂ adopts properties that lie midway between a gas and a liquid. In this state, it behaves as a supercritical fluid, where it expands like a gas just has a density like to that of a liquid.

Supercritical CO_ii is an of import commercial and industrial solvent since it enables chemical extraction at low temperatures while remaining stable. It also presents low toxicity and minimal environmental bear on.

Book of gases at STP

The book of a gas is a function of both pressure and temperature. At STP, 1 mol of gas occupies 22.4 liters (L) of volume. In other words, the molar book of a gas at STP is 22.4 50. This book can be found using the ideal gas police: PV=nRT (due north = number of moles, R = gas abiding).

In addition to the ideal gas law, other laws and formulas used in standard conditions for temperature and pressure are the following:

Gay-Lussac's law: P₁T₂ = P₂T₁
Charles'due south law: V₁T₂ = V₂T₁
Boyle's police: P₁Five₁ = P₂V₂

Incorrect assumption of standard conditions tin can result in calculation errors, which tin drastically affect the last outcome of the experiment. That's why, when defining the volume, it is necessary to state its pressure and temperature conditions. These weather condition must too be stated by defining book-dependent quantities, like molar volume, density and volumetric period.

Properties of water at STP

At STP, the density of pure h2o (H₂O) is 62.4 pounds per cubic human foot (lb/ft³). Produced water contains numerous impurities, such as salts, which is why its density is higher than the density of pure water. Water-specific gravity is defined as the ratio of density of the produced water to that of pure h2o.

Some other property of h2o is its formation volume factor. The germination volume gene of produced water is the volume occupied in a reservoir at its prevailing pressure and temperature divided past the water volume plus its dissolved gas at STP. Thus, it is expressed as the following:

Bw=Vres / Vst (B_{due west} = formation volume factor of water, Five_res = water volume in reservoir condition, V_st = water book at STP)

The density and formation book factor of h2o, along with other backdrop like specific gravity, salinity, viscosity and compressibility, are all ofttimes used in oil and gas field management.

STP vs. NTP vs. SATP

Laboratory weather rarely involve STP, so other reference conditions are also used for measurements and calculations of physical and chemical processes and properties of matter.

Normal temperature and pressure (NTP) is 1 such standard reference for temperature and pressure. It is defined as air at the post-obit weather condition:

Temperature: 20 degrees Celsius (293.15 degrees Kelvin, 68 degrees Fahrenheit)
Force per unit area: 1 atm (101.325 kilonewton per square meter, 101.325 kPa, fourteen.vii PSI absolute, 0 PSI gauge, 29.92 inches of mercury, 407 inches of H_twoO, 760 Torr)
Density: i.204 kilogram per cubic meter (0.075 lb/ftⁱⁱⁱ)

At these conditions, the volume of 1 mol of a gas is 24.0548 L.

Like STP and NTP, standard ambient temperature and pressure (SATP) is too used in chemistry as a reference standard. It is defined as the following:

Temperature: 25 degrees Celsius (298.15 degrees Kelvin)
Pressure: 1 atm (101.325 kPa)

At these conditions, the book of 1 mol of a gas is 24.4651 L.

In addition to STP, NTP and SATP, two other common standards for pressure and temperature are the International Standard Temper (ISA) and the U.S. Standard Atmosphere.

Under ISA, standard temperature is 15 degrees Celsius, standard pressure is 1 atm and relative humidity is 0%. U.S. Standard Atmosphere is divers as temperature of 288.15 K (15 degrees Celsius, 59 degrees Fahrenheit) at a ocean level 0 kilometer geopotential superlative and pressure of 1 atm (101.325 kPa, 1,013.25 hectopascals, ane,013.25 millibars, 760 millimeters of mercury). The two standards have the aforementioned definition of standard temperature and pressure at altitudes up to 65,000 anxiety above ocean level. At higher altitudes, they differ slightly in the temperature ranges.

Many other organizations set their own standards for temperature and force per unit area. These include the following:

International System for Standardization;
Us Environmental Protection Agency;
U.S. Occupational Condom and Wellness Administration;
System of the Petroleum Exporting Countries; and
U.S. Federal Aviation Administration.

The precise definition of STP depends on the organization. That's why it's best to explicitly state the temperature and pressure reference conditions instead of simply stating that a measurement was performed at STP or standard conditions.

This was final updated in July 2022

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