Torr

(noun)

A unit of pressure equal to one millimeter of mercury (760 torr = 101,325 Pa).

Related Terms

Examples of Torr in the following topics:

  • SI Units of Pressure

    • In chemistry, it is more common to express pressures in units of atmospheres or torr:
    • 1 atm = 101325 Pa = 760 torr $\approx$ 760 mm Hg
    • Torr and millimeters of mercury (mm Hg, defined as a one millimeter difference in the height of a mercury barometer at 0°C) are nearly equivalent.
    • 1 bar = 105 N/m2 = 750.06 torr = 0.987 atm.

  • Vapor Pressure of Nonelectrolyte Solutions

    • Calculate the vapor pressure of a solution consisting of 3 moles of a nonvolatile solute and 15 moles of water at 25 oC, given that the vapor pressure of pure water at 25 oC is 23.8 torr.

  • The Mass Spectrometer

    • Atmospheric pressure is around 760 torr (mm of mercury).
    • The pressure under which ions may be handled is roughly 10-5 to 10-8 torr (less than a billionth of an atmosphere).

  • Background and Properties

    • Boiling points are given for 760 torr (atmospheric pressure), and those listed as a range are estimated from values obtained at lower pressures.

  • Collecting Gases Over Water

    • The atmospheric pressure is 754 torr, and the temperature is 295 K.
    • (At 295 K, the vapor pressure of water is 19.8 torr.)

  • Experiments in Latin America

    • The return of Joaquín Torres-García (1874–1949) to Uruguay in 1934 was decisive in the development of abstraction in Latin America.

  • The Ideal Gas Equation

    • Pressure (P), often measured in atmospheres (atm), kilopascals (kPa), or millimeters mercury/torr (mm Hg, torr)

  • Liquid to Gas Phase Transition

    • Because the typical pressure at the earth's surface is 1 atm (760 torr), this is the vapor pressure that a liquid must equal in order for it to be at its normal boiling point.
    • The intercepts of each curve with the horizontal line at 1 atm (i.e. 760 torr) indicate the normal boiling point of each liquid, ranging from -25 °C for methyl chloride to over 80 °C for fluorobenzene and 2-heptene.

  • Measurements: Gauge Pressure and the Barometer

    • Pressure, as determined by hydrostatic barometers, is often measured by determining the height of the liquid in the barometer column, thus the torr as a unit of pressure, but can be used to determine pressure in SI units .

  • Interventions in Latin America and the Middle East

    • In Paraguay, Alfredo Stroessner had been in power since 1954; in Brazil, left-wing President João Goulart was overthrown by a military coup in 1964 with the assistance of the US in what was known as Operation Brother Sam; in Bolivia, General Hugo Banzer overthrew leftist General Juan José Torres in 1971; in Uruguay, considered the "Switzerland" of South America, Juan María Bordaberry seized power in the 1973 coup.