Measurement of Pressure and Temperature

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Slide 1

Pressure and Temperature

William Thomson

“Lord Kelvin”

Slide 2

CA Standards

Slide 3

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

Slide 4

An Early Barometer

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

Slide 5

Pressure

Is caused by the collisions of molecules with the walls of a container

is equal to force/unit area

Slide 6

Standard Pressure

1 standard atmosphere (atm)

101.3 kPa (kilopascals)

14.7 lbs/in2

760 mm Hg (millimeters of mercury)

760 torr

Slide 7

Pressure

Pressure is the force created by the collisions

of molecules with the walls of a container

Slide 8

The Kelvin Scale

Slide 9

Standard Temperature

Standard Temperature equals:

273 Kelvin (273 K)

0 C

Slide 10

Converting Celsius to Kelvin

Gas law problems involving temperature require that the temperature be in KELVINS!

Kelvins = C + 273

°C = Kelvins - 273

Slide 11

Standard Temperature and Pressure “STP”

Either of these:

273 Kelvin (273 K)

0 C

And any one of these:

1 atm

101.3 kPa

14.7 lbs/in2 (psi)

760 mm Hg

760 torr

Slide 12

Standard Molar Volume

One mole of a gas at STP has a volume of 22.4 Liters

Slide 13

Mole Relationships

Mole

Atoms

or molecules

Liters

Grams

6.02 x 1023

Atomic

Mass

22. 4 L

22.4

L