Water Properties
Density
• The amount of atoms, or stuff, packed into
the same space.
Which is more dense?
• Cold or Hot Water
– Cold water-things that are cold become more
dense as they shrink
• The only exception is ice, cold water becomes
more dense until it freezes. It then expands!
Quickly watch water temperature
and density video
Temperature affect on ocean water
• Think back to our dissolved oxygen lab
• What happened as the temperature rose
with relation to the amount of oxygen in
the water?
• The same thing happens with salt in water
• Warmer the water-less salty-less dense
• Colder the water-more salt-more dense
Quickly watch density of salt water
video
Density of Salt Water
• What happens to the density of water the
deeper you go?
• It increases in density
• Why?
• The pressure from the water above is
pushing things tighter and tighter!
Watch NASA Video on
Temperature vs. Salinity
Depth
of
water
What variables might change
the salinity of the oceans?
• What if it rained near a very salty part of
the ocean?
• Precipitation would add more water and
have less salt.
• What if lots of water evaporated near a
salty part of a ocean?
• Evaporation will have less water, more
salt.
Which is more dense?
• Salt water or freshwater?
– Salt Water of course
• Why?
– There is more “stuff” in the water.
Practice
• I will be calling groups back to practice the
density of salt water, cold water, and warm
water.
• While you are at your seats you WILL
work on the following
• 39-50 in workbook
• Finish your vocabulary assignment for this
week.
Buoyancy
• Buoyancy-the upward force caused by the
difference in densities, or more simply-the
ability of things to float
• How is Buoyancy related to density?
• Things float because of density-if you are
less dense than something you will float
Watch Buoyant force video!
Practice Buoyancy
Title: How does density create
buoyancy
• Date: Today’s Date
• Directions: Answer all questions and
perform all activities
• 1. Fill your 2 liter bottle that has been cut
in half about ¾ full of water.
• 2. Place your boat that is on your desk on
top of the water.
• 3. What happens?
• 4. Why does it float?
• 5. How does the boat floating represent
buoyancy?
• 6. Remove your boat
• 7. What will happen when you throw a
penny into the water? Why?
• 8. How could we get our penny to float
using buoyancy of another object?
• 9. Place your boat into the water. Place
pennies into your boat until the density
becomes too great for buoyancy to keep
them afloat.
• 10. How many pennies did it take
counteract the upward force of buoyancy?
• Review Questions:
– 1. What is buoyancy?
– 2. Why is buoyancy important for boats?
Show to Stick or Not To Stick Video
Cohesion
• Ability of like substances to stick together
• Water binds to other water molecules to
create the cohesion of water.
Cohesion
• THIS IS WHY WATER DROPS LOOK A
LITTLE FUNNY
• What happens when you do a belly flop on
the water?
• You are breaking the cohesive bond
between water!
Practice
Title: Cohesion of water molecules
• 1. Place 1 drop of water onto a penny.
• 2. Draw a picture from the side of what
you see.
• 3. Why does the water drop have a dome
shape to it?
• 4.Keep placing drops on water onto your
penny until the drops overflow, be sure to
count
• 5. How many drops did it take?
• 6. Draw a picture of what your penny
looked like before you dropped it.
• 7. What might have caused your dome of
to break?
• 8. Repeat the process of making a large
dome of water. Then take 1 drop of soapy
water and observe what happens.
• Review:
– 1. What is cohesion?
– 2. Why do you think the soap broke the
cohesion of the water?
– 3. Why is cohesion important?
Adhesion
• Water molecules have the ability to stick to
different substances, sometimes they are
absorbed, sometimes they are not.
Show to stick or not to stick part of
video on adhesion
Adhesion Observations
Title: Adhesion of water to wood
• 1. Using your water bottle on your desk,
place your ruler at an angle above the
empty cut 2 liter bottle of water.
• 2. Do your best to squirt the top of the
ruler and make the water end up in the
empty two liter bottle.
• Review:
– 1. What is adhesion?
– 2. How did you demonstrate adhesion?
– 3. Why do you think adhesion is important to
the environment?
Capillary Action
• The ability of water to “climb”, or defy
gravity.
• This is how plants get their water and how
paper towels absorb water.
• The adhesion, ability of water to stick to
other substances, allows water to “climb”
• The attraction between the paper towel
and water is adhesive or its the stickiness
of water.
Practice Capillary Action
• 1. Holding one end of your paper towel,
dip the other end into the colored water
and watch it “climb”.
• Review
– 1.What is capillary action?
– 2. What causes capillary action?
– 3. Why is capillary action so important in
nature?
Surface Tension
• The cohesive and adhesive properties of
water create surface tension.
• Surface Tension-the strength between
water molecules on the surface of water.
Watch surface tension video
Practice Surface Tension
Title: Surface Tension of Water
•
•
•
•
1. Fill your plastic cup up almost to the top
2. Toss one paper clip into the water.
3. What happened and why?
4. Attempt to place 1 paper clip so that it
stays on top of the surface of the water
and does not sink.
• 5. Record your observations about what
you notice about the water once you get
one to float.
Specific Heat
• Water has a very high specific heat
• Specific Heat-the amount of heat needed
to heat up a substance
• Water takes a long time to boil and will
stay warm for a long time.
Specific Heat
• The beach in summer time
• Sand- cold in morning-Hot in afternoon
• Water-stays about the same temperature
all day and all night
Specific Heat
• The ocean water will not warm up until late
June. It will stay warm until late Sept.
• Why does it take so long to warm and yet
stay warm for a long time?
Watch Specific Heat video
Why did the ice cube melt faster on
the mystery object?
• The mystery element has a lower specific
heat therefore it will absorb heat faster.
Specific Heat Lab
Universal Solvent
• What does it mean when we say that water is
the universal solvent?
• water can dissolve more things than any other
substance
• Why do things dissolve in substance?
• They are soluble or they have the same polarity.
• Like dissolves like. The closer the polarity, the
charge, the more likely they will dissolve.
Watch solute and solvent video
Polarity
• Attraction between water, the universal
solvent, and other substances will cause
things to dissolve in them.
• Polar=Dissolve
• Non-Polar=will not dissolve
Watch Soluble vs. Insoluble Video
Practice Polarity
Substance
Oil
Sugar
Cornstarch
Salt
Soluble or
insoluble
Polar or NonPolar
Review of Polarity
• 1. What is the relationship between
polarity and solubility?
Tides
• What are tides?
• Tides are changes in the ocean depths at
the beach.
• What causes tides?
• The gravitational pull of the moon as it
rotates around the Earth.
• The oceans, as a result of cohesion move
as one.