Main Idea: Water has unique properties that make it essential for all life on Earth.
Objective: Relate the physical and chemical properties of water to Chapter 3: Matter and Change
Background Facts
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Atomic Structure
Comprised of two hydrogen atoms bonded to a single oxygen atom (H2O).
Exists naturally on Earth in all three phases of matter.
Water is colorless, odorless, tasteless, and has a neutral PH.
About 71% of Earth’s surface is covered by water.
About 70% of the mass of a cell (basic building block of life) is water.
Video Overview
Directions: Please attend each one of the water centers (labeled with a letter) to complete the table with
notes, examples of the property, and an illustration.
Property
A
Polar
Molecule
A
Universal
Solvent
B
Boiling &
Freezing
Point
Description, Importance, Examples
Illustration
B
Expands
as a Solid
C
Cohesion
C
Adhesion
C
Capillary
Action
D
Surface
Tension
D
Specific
Heat
Polar Molecule
H20 is polar covalently bonded molecule. Electrons are
shared unequally in a polar covalent molecule which gives
H2O a positive and negative end.
Oxygen dominates all the electrons in H2O due to its super
strong electronegativity (desire to gain electrons). Most of
the unique properties that we will review in today’s
investigation are possible due to water’s unique polarity.
** On your water note guide summarize the information and
illustrate an H2O molecule, and identify the positive end and
negative end.
Universal Solvent
Due to its high polarity, H2O can easily bond with, and thus dissolve, many
substances. This allows liquid water to dissolve and transport many essential
chemicals, minerals, and nutrients within living things. For example, take the
Sodium Chloride (NaCl), or table salt, and twist the top to shave some salt crystals
into the beaker of water. Stir the mixture. What happens to the salt?
Recall modeling the ionic bond between Na+ and Cl- (see above left).
When mixed with water the positive Sodium ions are swarmed by the negatively
charged side of the water molecules and the Chloride ions are surrounded by the
positively charged H2O end (see above right). In the process of mixing the with
water the Na+ and Cl- are separated and thus dissolved.
** On your water note guide summarize the information, list at least 4 examples of
things that dissolve in water, and add an illustration that shows water as a solvent.
Boiling & Freezing Point
Recall the definitions of boiling and freezing point…
Boiling Point: temperature at which a liquid turns to a gas (or vaporizes).
Freezing Point: temperature at which a liquid turns to a solid (or freezes).
H2O has a relatively high boiling point and low
freezing point.
This allows for the vast majority of H2O on Earth
to exist as a liquid, which is the most valuable
state for living organisms.
Discuss: Imagine that water boiled and froze at temperatures that were much
closer, like 70 OF and 90 OF. How would this affect your life? Could life exist ?
** On your water note guide summarize the information above and accompany it
with an illustration.
Expands as a Solid
H2O has a really unique density characteristic. Typically
when matter freezes (or solidifies) their particles come
closer together and the frozen solid is more dense than its
liquid counterpart. But when water molecules freeze, their
volume actually increases, thus making their density decrease when it turns to ice.
As a result, ice floats in liquid water.
Hypothesize: As a group, hypothesize why ice
being able to float is necessary for life on Earth.
Possible Answer: Ice floating ensures major bodies
of water do NOT completely freeze and kill all life (only freezes near the surface).
** On your water note guide summarize the information, explain its importance to
life on Earth (especially marine life), and add an appropriate illustration.
Cohesion
Water molecules form hydrogen bonds
with other water molecules allowing for
them to conjoin or stick together. This helps
gives water the ability to flow as a liquid.
Hypothesize: As a group, what if water did not form hydrogen bonds with other
water moelcules? What would the world be like?
** On your water note guide summarize the information and illustrate two H2O
molecules forming a hydrogen bond and/or a puddle of water.
Adhesion
Put your finger in the water and then remove it slowly.
What do you see on the edge of your finger?
Similar to cohesion, adhesion is the stickiness to other substances (not water). H2O
is highly adhesive due to its strong polarity. In fact, water is actually the most
adhesive non-metallic liquid!
List: As a group come up with 5-6 things to which water sticks.
** On your water note guide summarize the information, list at least 4 examples of
things that water sticks to, and illustrate one of those examples.
Capillary Action
When the adhesive forces joining water to another
substance are stronger than the cohesive forces
between individual liquid molecules, surface
tension, and any other external forces, such as
gravity. This allows water to travel upward (against gravity) through a tube.
Discuss: What are examples of living things that depend upon capillary action?
** On your water note guide summarize the information, explain why it necessary
for a certain living thing, and represent capillary action with a drawing or graphic.
Surface Tension
Can you balance a paper clip on water? Try it.
How many drops of water can you put on a penny?
Both of these are a result of surface tension.
The hydrogen bonds (cohesion) conjoining multiple
water molecules must break for them to separate. An
acting force is required to break these hydrogen bonds (e.g. gravity).
** On your water note guide summarize the information above and accompany it
with an illustration.
Specific Heat
Water has a very high specific heat or heat capacity, meaning it absorbs a lot of
thermal energy before changing its temperature.
This is why liquid water takes a considerable amount of
time to boil!
Pure water is bad conductor of heat and electricity, but an
excellent coolant.
Hypothesize: As a group, discuss how the high specific heat of water may be
important to living things on Earth.
Possible answer: This helps to regulate body
temperature in living organisms and climates on Earth.
Water (liquid), water vapor (gas), and ice (solid) all play
a key role in regulating the temperature on Earth and
keeping it relatively stable for life to exist.
** On your water note guide summarize the information, list at least 4 examples of
things that dissolve in water, and add an illustration that shows water as a solvent.
Interesting Water Facts (EPA):
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Only 3% of Earth’s water is fresh water. 97% of the water on Earth is salt water.
The water found at the Earth’s surface in lakes, rivers, streams, ponds, and swamps makes up only 0.3% of the
world’s fresh water.
68.7% of the fresh water on Earth is trapped in glaciers.
30% of fresh water is in the ground.
1.7% of the world’s water is frozen and therefore unusable.
Water covers 70.9% of the Earth’s surface.
Water can dissolve more substances than any other liquid including sulfuric acid.
More than 25% of bottled water comes from a municipal water supply, the same place that tap water comes
from.
A ten meter rise in sea levels due to melting glaciers would flood 25% of the population of the United States.
There is more fresh water in the atmosphere than in all of the rivers on the planet combined.
If all of the water vapor in the Earth’s atmosphere fell at once, distributed evenly, it would only cover the earth
with about an inch of water.
Water boils quicker in Denver, Colorado than in New York City.
Approximately 400 billion gallons of water are used in the United States per day.
Nearly one-half of the water used by Americans is used for thermoelectric power generation.
In one year, the average American residence uses over 100,000 gallons (indoors and outside).
It takes six and a half years for the average American residence to use the amount of water required to fill an
Olympic-sized swimming pool (660,000 gallons).
It takes seven and a half years for the average American residence to use the same amount of water that flows
over the Niagara Falls in one second (750,000 gallons).
American residents use about 100 gallons of water per day.
Americans use more water each day by flushing the toilet than they do by showering or any other activity.
In 1900, 25,000 American’s died of typhoid. By 1960, thanks to the use of chlorine in water treatment, that
number dropped to 20.
At 50 gallons per day, residential Europeans use about half of the water that residential Americans use.
Residents of sub-Saharan Africa use only 2-5 gallons of water per day.
The average faucet flows at a rate of 2 gallons per minute. You can save up to four gallons of water every
morning by turning off the faucet while you brush your teeth.
Taking a bath requires up to 70 gallons of water. A five-minute shower uses only 10 to 25 gallons.
A running toilet can waste up to 200 gallons of water per day.
The New York City water supply system leaks 36 million gallons per day.
If you drink your daily recommended 8 glasses of water per day from the tap, it will cost you about 50 cents
per year. If you choose to drink it from water bottles, it can cost you up to $1,400 dollars.
There are approximately one million miles of water pipeline and aqueducts in the United States and Canada,
enough to circle Earth 40 times.
The first water pipes in the US were made from wood (bored logs that were charred with fire).
The first municipal water filtration works opened in Paisley, Scotland in 1832
A gallon of water weighs 8.34 pounds.
A cubic foot of water weighs 62.4 pounds
An inch of water covering one acre (27,154 gallons) weighs 113 tons.
Water vaporizes at 212 degrees F, 100 degrees C.
It takes more water to manufacture a new car (39,090 gallons) than to fill an above ground swimming pool.
It takes more than ten gallons of water to produce one slice of bread.
Over 713 gallons of water go into the production of one cotton T-shirt.
1000 gallons of water are required to produce 1 gallon of milk.
Roughly 634 gallons of water go into the production of one hamburger.
Water is the only substance found on earth naturally in three forms: solid, liquid and gas.
At 1 drip per second, a faucet can leak 3,000 gallons per year.
Water makes up between 55-78% of a human’s body weight.