 |
| Tap near the footbridge at Urunga NSW |
Water is
unique in that it is the only natural
substance that is found in all three physical states—liquid, solid, and gas—at
the temperatures normally found on Earth.
Water freezes at 32° Fahrenheit (F) and boils at
212°F (at sea level, but 186.4° at 14,000 feet). Water is unusual in that the
solid form, ice, is less dense than the liquid form, which is why ice floats.
Water is called the "universal solvent" because it dissolves more
substances than any other liquid. This means that wherever
water goes, either through the ground or through our bodies, it takes
along valuable chemicals, minerals, and nutrients.
Pure water has a neutral pH of 7, which is
neither acidic (<7) nor basic (>7).
The water molecule is highly
cohesive—it is very
sticky. Water is the most cohesive among the non-metallic liquids.
Pure water, which you won't ever find in the natural environment, does not conduct
electricity. Water becomes a conductor once it starts dissolving substances
around it.
Water has a high specific heat index—it absorbs a
lot of heat before it begins to get hot. This is why water is valuable to
industries and in your car's radiator as a coolant.
The high specific heat
index of water also helps regulate the rate at which air changes
temperature, which is why the temperature change between seasons is gradual
rather than sudden, especially near the oceans.
Water has a very high surface tension. In other
words, water is sticky and elastic, and tends to clump together in drops rather
than spread out in a thin film, like rubbing alcohol. Surface tension is
responsible for
capillary
action, which allows water (and its dissolved substances) to move through
the roots of plants and through the tiny blood vessels in our bodies.
The density of water means that sound moves
through it long distances (ask a whale!). In sea water at 30°C, sound has a
velocity of 1,545 meters per second (about 3,500 miles per hour).
Air pressure affects the boiling point of water,
which is why it takes longer to boil a egg at Denver, Colorado
than at the beach. The higher the altitude, the lower the air pressure, the
lower the boiling point of water, and thus, the longer time to hard-boil an
egg. At sea level water boils at 212°F (100°C), while at 5,000 feet, water
boils at 202.9°F (94.9 °C).
Some of water's physical properties:
- Weight: 62.416 pounds/cubic foot at 32°F; 1,000 kilograms/cubic meter
- Weight: 61.998 pounds/cubic foot at 100°F; 993 kilograms/cubic meter
- Weight: 8.33 pounds/gallon; 1 kilogram/liter
- Density: 1 gram/cubic centimeter (cc) at 39.2°F, 0.95865 gram/cc at 212°F
Some water volume comparisons:
- 1 gallon = 4 quarts = 8 pints = 128 fluid ounces = 3.7854 liters
- 1 liter = 0.2642 gallons = 1.0568 quart
- 1 million gallons = 3.069 acre-feet = 133,685.64 cubic feet
Flow rates:
- 1 cubic foot/second (cfs) = 449 gallons/minute = 0.646 million gallons/day = 1.98 acre-feet/day
Read more about this story from USGS
No comments:
Post a Comment