Bulk Properties of Water

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Slide 1

Properties of Water

The first image taken by humans of the whole Earth. Photographed by the crew of Apollo 8, the photo shows the Earth at a distance of about 30,000 km. Space has no respect for “North” and “South” as the southern most tip of South America is at the top of the photo.

Slide 2

Boiling Point and Freezing Point

Source: CRC Handbook of Chemistry and Physics

Slide 3

Boiling Points for Water at Altitude

Source: NOAA

Slide 4

Density

Water reaches a maximum density of 1.00 g/cm3 at a temperature of 3.98C.

Water expands (becomes less dense) as it freezes

Slide 5

Rock Weathering

The expansion of freezing water exerts sufficient force to fracture rock, and is a significant cause of rock weathering.

Slide 6

Water’s Thermochemistry

Specific heat and Latent heat of phase change, as they apply to water.

Slide 7

Units for Measuring Heat

The Joule is the SI system unit for measuring heat:

The calorie is the heat required to raise the temperature of 1 gram of water by 1 Celsius degree

The British thermal unit (BTU or Btu) is the amount of energy needed to heat one pound of water by one degree Fahrenheit.

Slide 8

Specific Heat

The amount of heat required to raise the temperature of one gram of substance by one degree Celsius.

Slide 9

Specific Heat

The amount of heat required to raise the temperature of one gram of substance by one degree Celsius.

Slide 10

Specific Heat and Climate

How does water contribute to the moderation of climate in coastal communities?

Santa

Barbara

CA

Slide 11

Calculations Involving Specific Heat

cp = Specific Heat

Q = Heat lost or gained

T = Temperature change

OR

m = Mass

Slide 12

Energy and Phase Change

Along LEG ‘A’ water exists as a solid (ice), and the temperature increases as energy is absorbed.