Hon Env Sci
Name _________________________ Period _____
Ms. Sipe
Date _____________
Global Water, Water Cycle, and Properties of Water
Stations Investigation
Introduction
Water is the most important chemical compound on the face of the Earth and is responsible for
supporting life. Approximately 70% of the surface of the Earth is covered with water, as shown
by the “blue marble” photos taken from space. So, why then is water considered a limited
resource?
Although we generally take the availability of potable water- water available for human
consumption- for granted in this country, most of the water that covers planet Earth is
saltwater. If you remember back to Biology, humans can only survive about a week without
potable water and cannot drink saltwater - it dehydrates cells and would cause death sooner
than not drinking any water at all! Of the total water available on Earth, approximately 97% of
it is salt water, and approximately 3% is freshwater. Of the total freshwater resources,
approximately 30% is underground and approximately 1% is surface water. That leaves
approximately 69% of freshwater that is unavailable due to being locked up in glaciers and ice
caps, which is why potable water is considered a limited resource.
Objective
In this investigation, you will complete activities related to the chemistry of water and
demonstrating the global distribution of water, per capita water usage, and the continuous flow
of water on, above, and below the surface of the Earth as it changes states between solid,
liquid, and gas.
Procedure
Read through the investigation handout thoroughly before beginning any activities, visit all
stations, and restore the station to its original condition.
Hon Env Sci
Name _________________________ Period _____
Ms. Sipe
Date _____________
Station 1. Global Water Distribution. Examine the global water distribution chart below and
then answer the questions.
1. What % of water is saline (saltwater)? ________
Freshwater? _________
2. What % of total freshwater is locked up in ice caps and glaciers? ________
3. What % of freshwater is ground water? _________.
Surface water? _______
4. What % of surface fresh water do lakes and rivers make up? __________ Why is this %
so important?
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
Hon Env Sci
Name _________________________ Period _____
Ms. Sipe
Date _____________
Station 2. Per capita water usage.
How much water do you use daily?
How much water do you use when you take a shower? Wash a load of clothes? Flush a toilet?
Even brush your teeth? One important measurement of water use is how much water one
person uses in one day, or per-capita water use (per is Latin for by and capita is Latin for head).
The number is usually expressed as gallons of water used per person per day.
To make things consistent for this activity, let's consider a rainy and cold Saturday when you
happen to stay home all day. Think of the water-using activities you do: take a shower, brush
your teeth, maybe wash dishes and clothes, etc.
Go to the following USGS website: http://ga.water.usgs.gov/edu/sq3.html and complete the
online questionnaire. Fill in the boxes with your water-use activities using the drop down tabs,
choose the submit button, and then you’ll receive an estimate of how many gallons of water you
used.
Answer the following (make sure to include units where applicable):
1. What is your per capita use of water:
_____________________________
2. Looking at the US map of water usage, what is the total estimated usage of water in
New Jersey daily? ____________________________
3. What is the population in New Jersey? ________________________
4. Using your answers from #3 & #4, calculate the average water usage per person in New
Jersey? ________________
5. How does your per capita use of water compare to the number calculated in #4?
________________________________________________________________________
6. What other uses of water, not included in the survey, may affect your actual per capita
use of water and caused the difference you noticed in question #5?
________________________________________________________________________
________________________________________________________________________
Hon Env Sci
Name _________________________ Period _____
Ms. Sipe
Date _____________
Station 3: The Water Cycle
The water cycle describes the existence and movement of water on, in, and above the Earth.
Earth's water is always in movement and is always changing states, from liquid to vapor to ice
and back again. The water cycle has been working for billions of years and all life on Earth
depends on it continuing to work.
Examine the water cycle diagram below. Put the letter from the diagram in front of the term
that is being depicted. You may need to look some of the terms up in the text or on the internet.
[
[
[
[
[
[
[
[
[
] Condensation
] Evapotranspiration
] Groundwater discharge
] Infiltration
] Snowmelt runoff to streams
] Streamflow
] Surface runoff
] Water storage in ice and snow
] Desublimation
[
[
[
[
[
[
[
[
[
] Evaporation
] Freshwater storage
] Groundwater storage
] Precipitation
] Spring
] Sublimation
] Water storage in the atmosphere
] Water storage in oceans
] Plant uptake
Hon Env Sci
Name _________________________ Period _____
Ms. Sipe
Date _____________
Station 4. Phase Diagram. Examine the diagram below and then answer the questions that
follow.
1. Define the following terms based on what you see in the diagram above.
a. Melting
____________________________________________________________
b. Freezing
____________________________________________________________
c. Condensation ____________________________________________________________
d. Vaporization ____________________________________________________________
e. Sublimation
____________________________________________________________
f. Deposition
____________________________________________________________
2. Which phase(s) of the water cycle is represented by vaporization?
___________________________________________________________________________
3. Which phase above occurs directly prior to precipitation? _____________________________
4. The “white cloud or fog” you see when dry ice is set out at room temperature represents
which phase in the water cycle? ___________________________________________________
Hon Env Sci
Name _________________________ Period _____
Ms. Sipe
Date _____________
Station 5: The Structure of Water- Chemical and Molecular Formulas
1. What is a chemical formula?
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
2. What is the chemical formula for water?
3. Build the molecular model of water using the molecular model kit provided. Sketch the
model in the space provided below. Color your sketch- use the same colors as in the
molecular modeling kit.
4. What does the molecular formula for water reveal that the chemical formula does not?
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
5. Based on the water molecule you’ve constructed, what is the shape of water molecule?
Hon Env Sci
Name _________________________ Period _____
Ms. Sipe
Date _____________
Station 6: Water- Bonding & Polarity
1. Define an ionic compound. Give an example.
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
2. Define a covalent compound. Give an example.
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
3. Is water an ionic or covalent compound? _________________________________________
4. What is meant by the term “polar” or “polarity”?
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
5. Is water a polar molecule? Explain your reasoning.
___________________________________________________________________________
___________________________________________________________________________
6. What is a hydrogen bond?
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
Hon Env Sci
Ms. Sipe
Name _________________________ Period _____
Date _____________
7. Draw four water molecules and use dashed lines between them to represent hydrogen
bonding that exists. Use solid lines to represent covalent bonds. Show the S+ and Scharges on the correct atoms.
8. How does the polarity of water and hydrogen bonding account for properties that sustain
life?
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
Hon Env Sci
Ms. Sipe
Name _________________________ Period _____
Date _____________
Station 7: Water- The Universal Solvent
Water is capable of dissolving a variety of different substances, which is why it
is such a good solvent. In fact, water is called the "universal solvent" because
it dissolves more substances than any other liquid. This is important to every
living thing on earth. It means that wherever water goes, either through the
air, the ground, or through our bodies, it takes along valuable chemicals,
minerals, and nutrients.
It is water's chemical composition and physical attributes that make it such an excellent
solvent. Water molecules have a polar arrangement of oxygen and hydrogen atoms—one side
(hydrogen) has a positive electrical charge and the other side (oxygen) had a negative charge.
This allows the water molecule to become attracted to many other different types of
molecules. Water can become so heavily attracted to a different molecule, like salt (NaCl), that
it can disrupt the attractive forces that hold the sodium and chloride in the salt molecule
together and, thus, dissolves it.
At the molecular level, salt dissolves in water due to electrical charges and due to the fact that
both water and salt molecules are polar, with positive and negative charges on opposite sides in
the molecule. A salt molecule consists of a sodium and chloride atom, and they are called ions
because they both have an electrical charge—the chloride ion is negatively charged and the
sodium ion is positively charged. Likewise, a water molecule is ionic in nature, but the bond is
called covalent, with two hydrogen atoms both situating themselves with their positive charge
on one side of the oxygen atom, which has a negative charge. When salt is mixed with water,
the salt dissolves because the covalent bonds of water are stronger than the ionic bonds in the
salt molecules.
The positively-charged side of the water molecules
are attracted to the negatively-charged chloride
ions and the negatively-charged side of the water
molecules are attracted to the positively-charged
sodium ions. Essentially, a tug-of-war ensues with
the water molecules winning the match. Water
molecules pull the sodium and chloride ions apart,
breaking the ionic bond that held them together.
After the salt molecules are pulled apart, the
sodium and chloride atoms are surrounded by
water molecules, as the diagram above shows. Once this happens, the salt is dissolved,
resulting in a homogeneous solution.
Hon Env Sci
Ms. Sipe
Name _________________________ Period _____
Date _____________
Part A. Define the following terms.
1. Solute
________________________________________________________________________
________________________________________________________________________
2. Solvent
________________________________________________________________________
________________________________________________________________________
3. Solution
________________________________________________________________________
________________________________________________________________________
4. Homogeneous Solution
________________________________________________________________________
________________________________________________________________________
5. Heterogeneous Solution
________________________________________________________________________
________________________________________________________________________
6. Ion
________________________________________________________________________
________________________________________________________________________
Hon Env Sci
Name _________________________ Period _____
Ms. Sipe
Date _____________
Part B. Use the introductory information and internet to answer the following.
1. Why is water called the “Universal Solvent”? Include the important physical attributes
and chemical composition in your answer.
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
2. Explain how your own kidneys and water's solvent properties make them a great pair in
keeping us alive and healthy.
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
3. Explain how salts dissolve in water.
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
Hon Env Sci
Name _________________________ Period _____
Ms. Sipe
Date _____________
Station 8: Cohesion & Surface Tension
Cohesion refers to the tendency of molecules of the same kind to
stick to one another. The cohesive forces between similar liquid
molecules are responsible for the phenomenon known as surface
tension. The molecules at the surface (of a glass of water, for
example) do not have other water molecules on all sides of them
and so they cohere more strongly to those directly next to and below them, but not above. The
stronger cohesion between the water molecules as opposed to the attraction of the water
molecules to the air makes it more difficult to move an object through the surface than to move
it when it is completely submersed.
The cohesive forces between molecules in a liquid are shared with all neighboring molecules.
Those on the surface have no neighboring molecules above and, thus, exhibit stronger
attractive forces upon their nearest neighbors on and below the surface. Surface tension could
be defined as the property of the surface of a liquid that allows it to resist an external force,
due to the cohesive nature of the water molecules.
Water molecules want to cling to each other. At the
surface, however, there are fewer water molecules to cling
to since there is air above (thus, no water molecules). This
results in a stronger bond between those molecules that
actually do come in contact with one another, and a layer of
strongly bonded water (see diagram to the left). This
surface layer (held together by surface tension) creates a
considerable barrier between the atmosphere and the
water. In fact, other than mercury, water has the greatest
surface tension of any liquid.
Hon Env Sci
Name _________________________ Period _____
Ms. Sipe
Date _____________
Part A. Define the following terms.
1. Cohesion
___________________________________________________________________________
___________________________________________________________________________
2. Surface Tension
___________________________________________________________________________
___________________________________________________________________________
Part B. Research and provide an explanation for why or how the following are examples of
surface tension. Do not just say “due to surface tension”.
1. Why can small insects like the water strider shown at the top of the station handout can
walk on water?
___________________________________________________________________________
___________________________________________________________________________
2. When camping one night during the summer, it starts to rain. You wake up in the morning
relieved that your sleeping bag and belongings are dry. However, when you sit up and
accidently bump the side of the tent, water drips through. Why?
___________________________________________________________________________
___________________________________________________________________________
3. Washing clothes in cold water may be just as effective as washing with hot water. Why?
(Hint: Think about the water temperature and the use of soaps or detergents).
___________________________________________________________________________
___________________________________________________________________________
4. Explain why bubbles are round and rain drops are spherical.
___________________________________________________________________________
___________________________________________________________________________
Hon Env Sci
Name _________________________ Period _____
Ms. Sipe
Date _____________
Part C. Surface Tension Demonstration.
Materials:





A penny
A pipette
A small beaker of water
A small beaker with dish soap
Paper towels
Procedure:
1. Predict how many drops of water will fit on top of a penny.
Water
Water
Soapy
2. Drop water on top of the penny one at a time until it drips over onto the lab table. Observe
the water carefully between each subsequent drop. How many drops fit on the penny
before it spilled?
Water
Soapy
Water
3. Sketch the penny with the water on top right before it spilled.
Water on penny
Soapy water on penny
4. Repeat the demonstration with soapy water and discuss your results. Were the results the
same or different? Explain.
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________