Lesson 2: Water on Earth
Name: _________________________
Blue Marble Animation
Date: ____________ Pd: ______
Things to consider while you are watching….

What observations can you make about this
animation of Earth rotating?
Ocean Facts
Does the northern or southern hemisphere contain
more land?
Which ocean basin is the largest?
• Ocean covers approx. _____ of earth’s surface
• Five oceans
• Pacific, Atlantic, Indian, Arctic, Southern
• _____ of earth’s water is saltwater
•
_____ of earth’s water is freshwater
•
1% is liquid
•
2-3% contained in ____________ and sea ice caps
in polar regions
Earth’s 4 “spheres” are constantly changing
•
Hydrosphere – water
•
Bodies of marine animals are ______ water by mass
•
Biosphere - life
•
Atmosphere – air
•
Lithosphere - _____
Ocean as a resource
•
____________________ resource – ocean replenishes itself naturally over relatively short periods
of time
•
•
______________________ resource – exhausted faster than they are naturally replaced
•
•
Constant influx of water from rivers and rain
Ex: natural gas and minerals
Humans must be careful to use ocean resources wisely
•
Ex: ___________________
Water for thought….Compare and contrast salt water and freshwater.
__________________________________________________________________________
__________________________________________________________________________
Demo: The Properties of Water
1. Your teacher will conduct Demonstration 1, allowing cold water to flow down the side of a beaker filled with very
warm water.
a. Record a hypothesis for what will happen in this demonstration. If _____________________________________
_______________________________________, then _______________________________________________
___________________________________________________________________________________________
b. Draw and label the results that you observe for this demonstration.
2. Your teacher will conduct Demonstration 2, placing ice cubes into cold water.
a. a.
Write a hypothesis for what will happen in this demonstration. If ________________________________
_______________________________________, then _______________________________________________
___________________________________________________________________________________________
b. Draw and label a beaker to illustrate the results of this demonstration.
3. How can you relate these two demonstrations to what you know about the ocean? ____________________________
______________________________________________________________________________________________
______________________________________________________________________________________________
Lab 1: Freezing, Melting and Boiling
Safety Notes:
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Dry ice burns skin! Anyone handling dry ice must wear work gloves.
Safety goggles must be worn for this investigation.
Handle thermometers and rubber stoppers carefully to avoid injury.
Materials:
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Dry ice
Work gloves
Safety glasses
Saltwater
Tap water
Thermometers or temperature probes, ranging from below
0 ˚C to above 100 ˚C
Test tubes
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Rubber stoppers (must fit test tubes
and thermometers)
Test tube labels or grease pencils
Beakers
Tongs
Hot plates
Stirring rods
Stopwatches
Phase Changes of Water I: Freezing Point
2. Follow the procedures with your lab group. Have one group member read each step aloud.
a.
Check to be sure your group has all of the necessary materials for this procedure. This experiment
requires the use of solid carbon dioxide, referred to as dry ice. When the solid dry ice is heated above
approximately -78 ˚C (-108 ˚F), it changes phase directly from a solid to a gas, bypassing the liquid state of
matter. This process is called sublimation. Dry ice is commonly used as a cooling agent. It is often used to
keep prepared meals or meats frozen during shipping.
b.


c.
Prepare 2 test tubes each about ¾ full of the following liquids. Allow them to sit in a beaker:
1 with tap water
1 with saltwater
Label the tubes.
d.
Place a rubber stopper and thermometer in each test tube. The thermometer bulb should be
surrounded by liquid, not resting on the bottom. Your team will be determining the freezing points of each
of the tap and saltwater samples.
e.
Make predictions: How will the freezing point compare between the samples?
___________________________________________________________________________________
___________________________________________________________________________________
___________________________________________________________________________________
f.
You will now use dry ice to cool the substances enough to determine their freezing points.

Your teacher will provide you with the Phase Changes of Water I Worksheet.

Using gloves or tongs, carefully place a chunk of dry ice into each of the 2 beakers.

Move the test tubes into the beakers with the dry ice.

Record the temperature of each test tube every 30 seconds. In the Notes column, note any changes you
observe in the substances.
g. Recall that freezing indicates the point at which a liquid is changing into a solid. Once the substances are
frozen, continue to record temperatures for 120 seconds.
h.
Dispose of dry ice as directed by your teacher.
Phase Changes of Water I Worksheet
Tap Water
0 sec.
30 sec.
60 sec.
90 sec.
120 sec.
150 sec.
180 sec.
210 sec.
240 sec.
270 sec.
300 sec.
330 sec.
Saltwater
Notes
Phase Changes of Water II: Melting and Boiling Points
Now your team will determine the melting and boiling points of one water sample each of frozen tap and frozen
saltwater.
Safety Note: Be very careful when heating substances—use gloves or tongs to handle the beaker and test tubes.
i.
Your teacher will provide you with the Phase Changes of Water II Worksheet and two, 250-mL beakers, each
with approximately 150 mL of crushed ice. One sample is frozen saltwater. The other is frozen tap water.
j.
Put a thermometer in each beaker. After one minute, record the temperature of each substance in your data table.
k. Place each beaker on a hot plate and turn them on. Hold the beakers in place with tongs. Carefully stir each
beaker every ½ minute with a stirring rod.
l.
Record the temperature of the contents of each beaker in the data table every 1 minute. In the Notes column, note
any changes you observe in the samples.
m. The substances are boiling when you notice rapid bubbling. Recall that boiling indicates that the water is
changing from a liquid phase to a gaseous phase. Continue to record temperatures for 2 minutes after the
substances begin to boil.
n. Clean up your laboratory station as directed by your teacher.
Questions:
When conducting an investigation, we often take measurements of things that vary, or variables. There are two major
types of variables—independent and dependent variables.

Something that is not changed by the other variables being measured is the independent variable. In these
experiments, the independent variable was time.

Something that depends on other factors is called a dependent variable. In these experiments, the dependent
variable was temperature. The temperature changed because of the other variable—the time the heat was added.
When drawing a graph, the independent variable should go on the bottom, or the x-axis. The dependent variable is plotted
on the side, or the y-axis. After you plot the data, you can examine the relationship between the independent and
dependent variables. Be sure to determine the appropriate units for each axis. Label the axes as well as the units.
Plot the results of your freezing, melting and boiling point experiments on graph paper.

Create one graph with the freezing point experiment data.

Create one graph that has both the melting and boiling point experiment data.

Add these to your notebook. Be sure each graph includes: 1) a title; 2) labeled x and y-axes; 3) units for each
axis; and 4) a key.
2. Describe what you observed when each liquid began to freeze. _______________________________________
___________________________________________________________________________________________
___________________________________________________________________________________________
3. List the observed boiling and freezing points of each substance in your chart.
Substance
Freezing Point
Boiling Point
Melting Point
Tap water
Saltwater
4.
Describe what happened to the temperature of the substances during each of the phase changes.
___________________________________________________________________________________________
___________________________________________________________________________________________
a. How was the temperature changing when the liquid became solid? _____________________________________
___________________________________________________________________________________________
___________________________________________________________________________________________
b. How was the temperature changing when the solid became liquid? _____________________________________
___________________________________________________________________________________________
___________________________________________________________________________________________
c. How was the temperature changing when the liquid became a gas? _____________________________________
___________________________________________________________________________________________
___________________________________________________________________________________________
d. How do the freezing and melting points compare for freshwater and saltwater? ___________________________
___________________________________________________________________________________________
___________________________________________________________________________________________
Phase Changes of Water II Worksheet
Tap Water
0 min.
1 min.
2 min.
3 min.
4 min.
5 min.
6 min.
7 min.
8 min.
9 min.
10 min.
11 min.
12 min.
13 min.
14 min.
15 min.
16 min.
17 min.
Saltwater
Notes
18 min.
19 min.
20 min.
21 min.
22 min.
23 min.
24 min.
25 min.
26 min.
27 min.
28 min.
29 min.
30 min.
31 min.
32 min.
33 min.
34 min.
35 min.
Water Chemistry – p. 26
Atoms
• Basic particle of a unique element
• Nucleus
• Neutrons: ___ electrical charge
• Protons: ___ charge
• Electrons: ____ charge
• Approx. 90 different naturally occurring
elements
• Label all 3 subatomic particles 
Isotopes
• Scientists use variations of isotopes to research earth’s _________________ over
many years
• Studied in ice core samples, sea shells, or cave formations
• Isotopes are variations of the same element that have same number of protons, different
number of neutrons.
• Ex: Fill in chart below for “heavy” vs. “light” oxygen
Heavy Oxygen (_______) Light Oxygen (_______)
Atomic Number (Protons)
Atomic Mass
Neutrons
Molecules and Bonding
• Oxygen and hydrogen are usually not found alone in a natural state
• Two or more atoms bond together to form molecules or compounds
• Atoms or molecules are more ______________ when they have a complete outer
shell
• Bonding – interactions between 2 atoms to fulfill ___________ rule
• Covalent – when 2 atoms ____________ electrons
• Ionic – when 1 atom ____________ an electron to another atom
• Draw along with Ms. Pitt
Covalent bonding – Oxygen gas
Ionic bonding - NaCl
Water
•
•
•
Asymmetrical combo of 1 oxygen and 2 hydrogens
Polar
• Oxygen end slightly __________________
while hydrogen end slightly _____________
Hydrogen bonding
• Attraction of negative oxygen of 1 water
molecule to positive hydrogen of another
water molecule
• Leads to _______________ or “stickiness”
of water molecules to one another
• Also leads to ________________ or
“stickiness” of water to other substances
Water and Density
•
Hydrogens bonds are relatively ________ in
comparison to ionic and covalent
•
However, collective H bonds are quite strong
•
One water molecule can h bond to ____ other
water molecules
•
How temperature affects water
•
Water molecules are situated as closely as they can be at 4˚C.
• ___________ density in liquid state
•
Below 4˚C, hydrogen bonding gets stronger and water molecules space out
•
Forms lattice structure and becomes solid ice
•
Water ____________ as it freezes
•
Becomes _______ dense
•
Most substances are more dense in solid state
Distinguish between atoms and molecules. ___________________________________________________________
_______________________________________________________________________________________________
What is density? How does the polarity of water molecules relate to the density of water? _____________________
_______________________________________________________________________________________________
Changing Phases of Matter
•
During a phase change, ____________________________ stays the same but heat energy
continues to be added.
•
Heat is absorbed and melts a solid into a liquid
•
Same thing happens from liquid to gas; this is called _______________________ or evaporation
•
The heat absorbed during a phase change is called ______________ heat
Heat Capacity
Water has tremendous ability to resist changes in temperature
•
Amount of heat needed to raise temp of 1g Water 1˚C is 1 calorie
•
During ________________ energy is taken away or given off
•
___________________ is when water changes from liquid to solid
•
__________________ when water changes from gas to liquid
•
• Sketch a phase change diagram for isopropyl alcohol (rubbing alcohol)
Freezes at -85.5˚C, Boils at 82.3˚C,
Phase Change Practice
•
Label the following: solid, liquid,
gas, freezing, melting,
condensation, vaporization
Lab 2: Floating and Sinking
Materials:
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1.
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Basins
Tap water
Triple-beam or electronic balance
Graduated cylinders
Rulers
Calculators
Various items to test floating and sinking
o Wood block
o Wood splint
o Vegetable shortening
o Pumice stone
o Rock
o Oil
o Seeds
o Nail
o Aluminum Foil
Follow the procedures with your lab group. Have one group member read each step aloud.
a. Check to be sure your group has all of the necessary materials for this investigation.
b.
1.
2.
3.
Prediction:
Observation:
Float or
Float or
4.
5.
Other
Item
c.
7.
Volume
Density
(mL or cm3)
(g/cm3)
Mass (g)
Observations
Sink?
6.
Sink?
List the items to be tested in Column 1. Confer with your group and decide on a prediction for each
item—do you predict that it will float or sink? List your predictions in Column 2.
Why do you think certain items float? What characteristics come into play in your decision? _______________
___________________________________________________________________________________________
___________________________________________________________________________________________
d.
Now, test your predictions for each item. List what you observe—whether the item floats or sinks—in
Column 3. List any other observations you have in Column 4.
e.
Measure the mass of each item, and record the mass in Column 5.
f.
Measure the volume of each item and record the volume in Column 6.
g.
Do you see any patterns in mass or volume of floaters and sinkers? Explain.
___________________________________________________________________________________
___________________________________________________________________________________
h.
Mass per unit volume is called density. Think of density as how compact something is. A lot of mass in
a small volume means that something is very dense. Less mass in a large volume means that something is
less dense.
Density is calculated by the following formula:
i.
Calculate the density of each item. Record the density in Column 7.
j.
Compare the densities of the floaters and sinkers.
k.
Using the tools at hand how could you determine the density of water? With your group, write down a
procedure for finding the density of water. Be very detailed listing and explaining your steps.
1. __________________________________________________________________________________
2. __________________________________________________________________________________
3. __________________________________________________________________________________
4. __________________________________________________________________________________
5. __________________________________________________________________________________
l. Follow your procedure and calculate the water’s density. Document your measurements along the way.
m. Now, knowing the correct formula, write and follow a similar procedure to find the density of ice. Follow
your procedure and record your measurements along the way.
1. ___________________________________________________________________________________
2. ___________________________________________________________________________________
3. ___________________________________________________________________________________
© U.S. Satellite Laboratory
4. ___________________________________________________________________________________
5. ___________________________________________________________________________________
n. Clean up your lab station as directed by your teacher.
Questions:
2. Compare the density of the floaters and sinkers to the density of water. _________________________
______________________________________________________________________________________
3. The density of freshwater is slightly less than that of saltwater. Would saltwater sink, float or behave in some
other fashion in freshwater? Why?
______________________________________________________________________________________
______________________________________________________________________________________
______________________________________________________________________________________
4.
Explain what happens in an oil spill.
___________________________________________________________________________________
___________________________________________________________________________________
___________________________________________________________________________________
Density and Marine Organisms – p. 34
Buoyancy – the __________________ force that keeps materials afloat
•
•
Have you ever lifted up someone in the water? Heavier or lighter?
What happens to the water level when you add something to a cup of water?
•
•
This is called ________________________
Things float better in seawater than freshwater
•
•
•
This is due to density
Freshwater: 1.00 g/cm3
Saltwater: ____ g/cm3
Aquatic organisms use buoyancy and displacement to maintain ________________ buoyancy
•
Ex: phytoplankton have oil deposits in shells
• Oil is less dense than water
© U.S. Satellite Laboratory
•
•
Ex: jellyfish
• _________________ that are 90% water, some float on surface, some rely on
neutral buoyance to maintain position in water column
Ex: sargassum
• Seaweed with air sacs
• Allows for ample light absorption for
photosynthesis
Polar Bear Sea Ice Animation
•
Marine organisms are also affected by density of
water’s solid form
•
Animals in polar regions are very dependent on sea ice
•
Polar bears, penguins, fish
•
Insulates water below
•
Reflects sun
 Check for Understanding – discuss with your table partners the following questions and write
down an answer in your own words.
o What is buoyancy? How does it allow large objects like massive whales to float?
___________________________________________________________
____________________________________________________________
o Describe how the structure of the sargassum helps it to float on water.
____________________________________________________________
____________________________________________________________
o How does the fact that ice floats affect marine animals?
____________________________________________________________
____________________________________________________________
o Describe the relationship between the movements of the polar bear and the seasonal
changes in sea ice. How can you explain this relationship?
___________________________________________________________
___________________________________________________________
© U.S. Satellite Laboratory