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Pressure and Temperature

Pressure and Temperature. William Thomson “Lord Kelvin”. Measuring Pressure. The first device for measuring atmospheric pressure was developed by Evangelista Torricelli during the 17 th century. The device was called a “barometer”. Baro = weight Meter = measure. An Early Barometer.

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Pressure and Temperature

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  1. Pressure and Temperature William Thomson “Lord Kelvin”

  2. Measuring Pressure The first device for measuring atmospheric pressure was developed by Evangelista Torricelli during the 17th century. The device was called a “barometer” • Baro = weight • Meter = measure

  3. An Early Barometer The normal pressure due to the atmosphere at sea level can support a column of mercury that is 760 mm high.

  4. is caused by the collisions of molecules with the walls of a container is equal to force/unit area can be measured using a variety of units Pressure

  5. Pressure • Pressure is the force created by the collisions • of molecules with thewalls of a container

  6. 760 torr 760 mm Hg (millimeters of mercury) 101.3 kPa (kilopascals) 1 standard atmosphere (atm) Standard Pressure

  7. Converting Pressure Units Gas law problems involving pressure require that the pressure be in the SAME UNITS! 1 atm = 101.3 kPa= 760 mm Hg Converting kPas to atms x atms= ____kPas 1atm 101.3 kPa Converting kPas to mm Hg x mm Hg= ____kPas 760 mm Hg 101.3 kPa

  8. Converting Pressure Units 1 atm = 101.3 kPa= 760 mm Hg A gas sample has a pressure of 800.0 mmHg. What is the pressure of this gas sample in atmospheres and in kilopascals? Converting mm Hg to atms x atms= 800 mm Hg 1atm 760 mm Hg Converting mm Hg to kPas x kPas = 800 mm Hg 101.3 kPa 760 mm Hg x = 1.053 atm x = 106.6 kPa

  9. Converting Pressure Units 1 atm = 101.3 kPa= 760 mm Hg A tank of oxygen is under a pressure of about 4.00 x 103kPa. Express this pressure in millimeters of mercury. Converting kPas to mm Hg x mm Hg = 4 x 103kPas 760 mm Hg 101.3 kPa x = 3.00 x 104 mm Hg

  10. has many applications (in real life!) Here’s one of those applications ! Air Pressure

  11. The Kelvin Scale

  12. Standard Temperature • Standard Temperature equals: • 273 Kelvin (273 K) • 0 C

  13. Converting Celsius to Kelvin Gas law problems involving temperature require that the temperature be in KELVINS! Kelvins = C + 273 °C = Kelvins - 273

  14. Either of these: • 273 Kelvin (273 K) • 0 C Standard Temperature and Pressure“STP” • And any one of these: • 1 atm • 101.3 kPa • 760 mm Hg • 760 torr

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