Unformatted text preview: Physical Properties of Water
Why is Earth so different or is it?
Hydrological Cycle Boil at -70˚ C Freeze at -90˚ C By the way:
1 gallon = 4 quarts = 8 pints = 128 ounces = 231 cubic inches
1 liter = 0.2642 gallons = 1.0568 quart = 61.02 cubic inches
1 million gallons = 3.069 acre-feet = 133,685.64 cubic feet
Planners estimate that one acre-foot serves the domestic needs
of one to two families (ﬁve to eight people)
65,000 gallons per year per person; ~1,250 gallons per week Here's a quick rundown of some of water's properties:
Weight: 62.416 pounds per cubic foot at 32 F °
Weight: 61.998 pounds per cubic foot at 100 F °
Weight: 8.33 pounds/gallon, 0.036 pounds/cubic inch
Density: 1 gram per cubic centimeter (cc) at 39.2 F,
0.95865 gram per cc at 212 F True or False
(1) Water contracts (gets smaller) when it freezes.
(2) Water has a high surface tension.
(3) Condensation is water coming out of the air.
(4) More things can be dissolved in sulfuric acid than in water.
(5) Rainwater is the purest form of water.
(6) It takes more energy to heat water at room temperature to
212˚ F than it does to change 212˚ F water to steam.
(7) If you evaporate an 8-inch glass full of water from the
Great Salt Lake (with a salinity of about 20% by weight), you
will end up with about 1 inch of salt.
(8) Sea water is slightly more basic (the pH value is higher)
than most natural fresh water.
(9) Raindrops are tear-shaped.
(10) Water boils quicker at Denver, Co. than at the beach. The earth appears to be unique in our solar system in that it
contains an enormous amount of water, and that water has
existed in a form not too different from its present state
for billions of years (How do we know this?). Given that the
laws of the nature operate everywhere in the solar system, we
have to question why we are so privileged to have large bodies
of liquid water on our planetary surface for so long a time.
What makes the earth different from the other planets?
1) How did the earth acquire such a large amount of water in
the ﬁrst place, and
2) Once acquired, how was it retained ? • The formation of the earth probably took a few
hundred million years to be completed. That is
to be compared with the time of about 1 billion years
since the earth has developed a solid crust.
• About the time the earth was formed, the sun became
large enough that the fusion reactions in the sun ignited.
This didn't happen smoothly, but likely in sputtering
way for a while. Each ﬂaring up of the sun sent streams
of particles sweeping out. If the earth
had an atmosphere at this time, it would have
been blown off leaving the earth as a rock with
neither air or water on its surface. Solar energy is created deep
within the core of the Sun. It is
here that the temperature
(15,000,000° C; 27,000,000° F)
and pressure (340 billion times
Earth's air pressure at sea level)
is so intense that nuclear
reactions take place. This
reaction causes four protons or
hydrogen nuclei to fuse together
to form one alpha particle or
helium nucleus. • After the sun stabilized, the earth went through a process of
releasing gases from its interior in a process called degassing.
Over a relatively short time, something like a few 100 million
years, enough material had been released to form the oceans
and to give the earth an atmosphere.
• There was no free oxygen in the atmosphere at this time, but
it was a collection of gases, largely ammonia, methane and
carbon dioxide, held to the earth by gravitational attraction.
• Fortunately, early in its history, the temperature of the earth
dropped below 212 degrees Fahrenheit, and the water
condensed into the oceans we know today. • In fact, the mass of water present in the oceans, now about
10(24) grams, is about the same as the mass of water that was
contained in the crust when the degassing process started.
Estimate the rate at which water is being lost today by
estimating the rate at which water molecules in the
atmosphere are dissociated into its constituent hydrogen
and oxygen. The hydrogen is light enough that it easily moves
off into space. Hydrogen loss decreases the amount of water
vapor in the atmosphere.
~ 5x10 (11) grams are lost this way each year. This amounts to
a volume of a cube about 100 yards on a side.
~ 2x10(21) grams lost to space since the beginning of the earth
thus amounts to about 0.2 percent of the water in the oceans. • This means that most of the water you see
on the earth was the very same stuff that
degassed from the crust when the earth was
only a few hundred million years old.
Fortunately, the water lost to space is
replaced by the same geologic processes
that formed the oceans originally. Atmospheric Evolution
• primordial gases, later lost from sun's radiation 2. exhalations from the molten surface (volcanic venting);
bombardment from icy comets
3. steady additions of carbon dioxide, water vapor, carbon
monoxide, nitrogen, hydrogen, hydrogen chloride,
ammonia, and methane from volcanic activity
4. addition of oxygen by plant/bacterial life "What makes the planets perfectly
spherical?" Do earthquakes have effects on water
sources? "What makes the planets perfectly
spherical?" "If water properties (such as boiling
point) changes at different elevations,
how does elevation affect people in high
elevations (considering we are made of
mostly water)? Why is the water still here on the earth?, is more difﬁcult
• It has to do with the changing nature of the atmosphere due
to evolution of life, speciﬁcally algae. The algae produced free
oxygen by photosynthesis which destroyed ammonia and
methane, so called greenhouse gases, just as the sun's
luminosity was increasing by about twenty ﬁve percent. If
that hadn't happened the oceans would have boiled away long
• In fact, we are the beneﬁciaries of an incredible balancing
act which allowed just enough heat to escape from the earth
to keep the oceans from boiling, but not so much as to cause
the earth to freeze solid. Hydrologic Cycle - is responsible for the largest movement of
a chemical substance on our planet. Water movement
determines climatic patterns, plant growth, heat energy
transfer, erosion rates, and rates of rock weathering
• evaporation (latent heat input) about 500,000 km3 enough to
cover the earth’s entire surface to a depth of about 1 m
• transportation (water vapor and liquid - transports sensible
• precipitation (latent heat release)
• inﬁltration (recharge groundwater)
• transpiration (plants release into atmosphere) Atmospheric Circulation Cells also explain variations in
precipitation with latitude: (Hadley, Ferrel)
0 degrees warm air rises, condenses- rain (low pressure)
30 degrees dry air descending and warms- deserts (high
60 degrees rain (low pressure)
90 degrees desert (high pressure)
Then Add continents
1. physical barriers- deflect the winds
2. thermal effects 1. Effect of continentsLocation of high and low pressure systems varies with
season as land heats and cools more than the sea
• sea breezes
Southern hemisphere more zonal circulation due to less
Orographic effects- rain shadow Arid Region (desert) down stream of mountains If water’s heat capacity and latent heat of
vaporization were much lower would we
still have rain and would puddles of
rainwater behave differently? ...
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- Winter '08