ACTIVITY I-WATER
LIFE DEPENDS ON THE UNIQUE PROPERTIES OF WATER
WATER INVESTIGATION
In this lab, the student will investigate the properties of water in an attempt to understand
how water behaves in relation to both living organisms and the environment. Water is
part of our everyday life: You will also compare water, a polar molecule, to vegetable oil,
a nonpolar molecule.
1. We can go months without food but can survive only a few days without water.
2. Sixty to ninety five percent of most organisms are made of water.
3. Two thirds of the molecules in our body are water molecules.
4. Living cells are filled with water.
5. Most chemical reactions in living organisms occur in water solutions.
6. Cells of living organisms are surrounded by water.
7. Water is the major means of transport for material in living organisms.
8. Life on earth could not have evolved without water.
9. Lubricant and cushion for many organs.
10. Coolant in temperature regulation.
As you do these labs try to develop an understanding of how water contributes to
the fitness of earth for life. Keep track of your data and answer the questions. This
will help you with your final product. Your final product will be a paper explaining
how water contributes to the fitness of earth for life. The paper should include the
following:
1. Explanation of why water is called a polar molecule.
2. Compare & contrast polar water to nonpolar vegetable oil
3. What does water’s polarity lead to?
4. Explanation of unique properties of water (adhesion, cohesion, surface
tension, capillary action, high specific heat, high heat of evaporation,
evaporative cooling, universal solvent, and ice less dense than liquid water).
5. What is responsible for these unique properties of water?
6. How are these unique properties important to living things? Give examples
for each.
7. How does water moderate earths environment (heat of vaporization, specific
heat, ice being less dense than liquid water and evaporative cooling)?
8. You must use data from your lab to support each property of water discussed
in your paper.
9. The following terms should be used in your paper:
a. Polar or polarity
b. Hydrophobic and hydrophilic
c. Hydrogen bonds
d. Solute, solvent, solution
10. Importance of water cycle.
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PART A: WHY IS THE WATER CYCLE IMPORTANT?
Water covers 75% of the earth’s surface. Despite this abundance of water, humans and
many other organisms have a major concern.
Discuss the following questions with your lab partners and record your answers in your
notebook.
a. Can we drink ocean water?
b. What are the sources of freshwater?
c. Is there enough of these sources to support non marine life?
Material: 150 ml beaker, graduated cylinder
Procedure:
1. Measure 100 ml of water and pour it into a beaker (this represents all the
fresh water on earth).
a. Estimate how much of the 100 ml of water is available for most land
organisms to use and record your answer in your notebook.
2. Remove 76 ml of the water from the beaker (this represents the water that is
frozen in the polar ice caps and glaciers).
a. Is this water readily available for use? Record your answer.
3. Discard the 76 ml of water.
4. Remove 23.6 ml of the water from the beaker (this is the amount of water
underground).
a. Is this water readily available for use by most organisms? Explain
your answer & record.
5. Turn your beaker upside down over a sink and observe.
a. What do you think this amount of water represents?
b. Relate this demonstration to the water cycle (this requires some
research and reading on your part).
PART B: DO WATER MOLECULES POSESS PARTIAL CHARGES?
Material: balloon
1. Run a thin stream of water from a sink.
2. Rub a balloon against your hair (this causes the balloon to become negative).
3. Place the balloon next to the stream of water but don’t allow it to get wet.
a. What do you observe? Record your answer.
b. What do you know about the atoms that bond to form a water molecule
that can explain your observation?
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PART C: HOW DO POLAR AND NONPOLAR MOLECULES INTERACT WITH
EACH OTHER?
Material: wax paper, dropper, glass slide, beaker with water, toothpick
1. Spread wax paper on a table (wax paper is a lipid, nonpolar, and hydrophobic).
2. Use an eyedropper to position 3 or 4 separate small drops of water on the paper.
a. Describe the shapes of the water drops and record.
b. Does it seem like water is sticking to itself? What is the name of this
property?
3. Wet a toothpick with water.
4. Bring the tip of the wet toothpick near, but not touching, one of the water drops.
a. Describe and record your observations.
b. Using your knowledge of chemical bonding, explain your observation.
c. Why do you think that plant leaves have waxy surfaces?
d. Predict what will be the shape of a drop of water on glass slide (glass is
polar) and record.
e. Why did you predict as you did?
5. Perform the experiment suggested in “d” to test your prediction.
a. What was your result? Why?
b. What property of water is demonstrated?
PART D: WHICH TYPE OF MOLECULE HAS A HIGHER SURFACE
TENSION, POLAR OR NONPOLAR?
Material: 2 Petri dishes, beaker, talcum powder, 2 toothpicks, liquid soap, vegetable oil,
staple
1. Add the polar liquid (water) to one Petri dish & fill. Add the nonpolar liquid (oil) to
another Petri dish & fill.
2. Using a clean and dry staple, try to gently lay the staple on the surface of water using
the surface tension for support. Retrieve the staple, dry it and try again if you don’t float
it on the first try.
a. What did you observe? Record
3. Using a clean and dry staple, try to gently lay the staple on the surface of oil using the
surface tension for support.
a. What did you observe? Record
b. How is a floating staple like a bug that can walk on water?
PART B:
1. Add water to a 250 ml beaker
2. Sprinkle a thin layer of talcum powder on the surface of the water in the beaker.
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3. Dip the end of a toothpick in liquid dish detergent (soap disrupts a certain type of
bond).
4. Touch the soapy end of the toothpick to the center of the water.
a. What do you observe? Record.
5. Repeat steps 1-3 using the vegetable oil instead of water.
a. What do you observe? Record
b. Compare your observations between water and vegetable oil
c. Explain the differences
d. Why must we be concerned about detergent pollution of our ponds and
lakes?
PART E: WHAT IS RESPONSIBLE FOR HIGH SURFACE TENSION AND
HOW CAN IT BE DISRUPTED?
Material: 1plastic Tupperware container, 3 toothpicks, liquid soap
1.
2.
3.
4.
Fill a clean plastic Tupperware container with water.
Place two toothpicks side by side on the surface in the center of the water.
Treat a third toothpick by dipping its point in liquid detergent.
Touch the tip of the treated toothpick between the floating sticks.
a. What do you observe? Record.
b. Using your knowledge of water chemistry and soap disrupting certain
bonds explain your observations.
Imagine two streams. In one stream a water strider floats on the surface of the
water. In the other stream the water strider sinks (can’t float on the water surface).
a. Based on the previous experiments D & E what might you
hypothesize about the second stream. Record your answer.
PART F: WHICH LIQUID HAS A GREATER CAPILLARY ACTION, POLAR
OR NONPOLAR?
Hypothesize which liquid (polar or nonpolar) will have greater capillary action.
Give a reason why you think this.
Material: 2 droppers, water, glass slide, vegetable oil, 2 capillary tubes
1. Using a separate dropper for each, place three drops of a polar liquid (water) on one
end of a glass slide and three drops of a nonpolar liquid (vegetable oil) on the other end
of the slide.
2. Using a capillary tube, gently touch the end of the tube to the drop of the polar liquid
and watch the results. Repeat the procedure with the same tube several times until the
results do not change.
3. Repeat step 2 using a new capillary tube and the nonpolar liquid.
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a. Observe what happened and record.
b. Explain your observation using your knowledge of water chemistry.
c. Relate this action of water to a biological purpose.
PART G: WHICH MOLECULE, POLAR OR NONPOLAR, ACTS AS A
BETTER SOLVENT FOR PIGMENTS?
PART I:
Material: 2 100 ml graduated cylinder, black vis-à-vis pen, 2 strips of chromatography
paper, scissors, ruler, salt, sugar, starch, lipid, 4 test tubes
1. Obtain two 100 ml graduated cylinders, and cut off two strips of chromatography paper
about a 31 cm long which should allow it to hang over the side of the cylinder (inside)
and reach the bottom.
2. Run the paper strip along the edge of a scissors to take the curl out of it if needed.
3. Place a single small drop of ink from a black vis-à-vis pen on each paper, about one
3.5 cm from the bottom, and let them dry completely.
4. Put 10 ml of water into one graduated cylinder and 10 ml of vegetable oil into the other
graduated cylinder and place one strip of paper in each cylinder so that the bottom end is
immersed in liquid and the drop of ink is just above the surface of the liquid. Fold the
paper over the topside.
5. Note the starting time.
a. How fast do you think water will climb a strip of chromatography paper?
Record your prediction in mm/time.
b. How fast do you think vegetable oil will climb a strip of chromatography
paper? Record your prediction in mm/time.
6. Watch and note the time at 5-minute intervals. Record the times and distances.
7. When the water climbs to the top of the paper, remove the paper from the water & oil,
and let it dry.
a. How did the ink change in each cylinder?
b. Glue the paper strips into your notebook and label each strip and the
colors on the strips.
c. How do you explain the results?
d. How close were your predictions?
PART II:
Place a pinch of salt (an ionic compound) in the bottom of a test tube. Place a pinch of
sugar in another test tube. Place a pinch of starch in a third test tube & place a pinch of
lipid in a 4th test tube. Add 10 ml of water to each test tube. Roll the test tubes between
your hands to mix the contents. Be careful not to drop the test tube during this process.
What happens to the salt crystals, the sugar crystals, and the starch?
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a. Was water a good solvent for all of the compounds you tested? Explain
your answer.
PART H: WHICH TYPE OF MOLECULE HAS GREATER ADHESION AND
COHESION, POLAR OR NONPOLAR?
Material: 2 droppers, 2 pennies, detergent, water, vegetable oil
1. How many drops of water can you place on the surface of a penny before it overflows?
a. Predict how many drops and record your prediction.
2. Drop water from the dropper onto a clean dry penny, keeping careful count of each
drop.
a. How many drops were you able to place on the surface of the penny
before it overflowed? Record.
3. How many drops of vegetable oil can you place on the surface of a penny before it
overflows?
a. Predict how many drops and record your prediction.
4. Drop vegetable oil from the dropper onto a clean dry penny, keeping careful count of
each drop.
a. How many drops were you able to place on the surface of the penny
before it overflowed? Record
b. Explain your results.
5. With your finger, spread one small drop of detergent on the surface of a dry penny.
a. Predict how many drops of water you think this penny will hold after
being smeared with detergent, more, less, or the same as before? Why?
Record your answers.
6. Test your prediction
a. How many drops were you able to place on the penny before it overflowed
this time? Record.
b. Did the detergent make a difference? Describe the effect of the detergent.
PART I: WHY DOES IT MAKE SENSE FOR CELL MEMBRANES TO BE
MADE UP OF LIPIDS?
Material: 10 ml graduated cylinder, cooking oil, water, test tube
1. Place 4 ml of water into a test tube.
2. Gently add 2 ml of cooking oil by tilting the test tube of water slightly and letting the
oil run slowly down the inside of the cylinder.
a. What happened?
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b. Which has a greater density, water or oil?
3. Shake the test tube holding your finger on top of opening to avoid spillage. Wait a few
minutes.
a. What was your result? Explain
b. This characteristic behavior of oil and water is of critical importance in
cell membranes (made of lipids) of living things. Research why this is so and
record.
PART J: WOULD YOU EXPECT A LIQUID TO EXPAND OR CONDENSE
WHEN IT FREEZES?
MATERIALS: tape, plastic food cup, food coloring, straw
1. Tape a straw to the bottom of a food jar so it stands vertically.
2. Fill the jar with water.
3. Add 4-5 drops of food coloring and stir.
4. Use a pen to mark the height of the water on the straw.
7. Have the teacher place the jar in a freezer overnight.
a. Describe what you see and record.
b. Explain the reason for your observation.
c. Why is this property of water important in street cracks and changes in
the environment that makes life more suitable?
Part K: WOULD YOU EXPECT A SOLID TO BE DENSER THAN ITS LIQUID?
Material: ice cubes, beaker
1. Place ice cubes in water.
a. What do you observe? Record.
b. Explain the reason for your observation.
c. Why is this property of water important for aquatic life?
PART L: WHICH TYPE OF MOLECULE REQUIRES MORE HEAT TO RAISE
ITS TRMPERATURE, POLAR OR NONPOLAR?
(DO NOT PERFORM THIS EXPERIMENT. JUST READ THE PROCEDURE
AND THE FOLLOWING RESULTS)
1. Using a balance measure out equal amounts of cooking oil and water and place in
separate beakers.
2. Place poultry pop timers in each beaker (they pop at 180 degrees F.)
3. Heat both beakers simultaneously on a hot plate until one of the timers pop. Record.
4. Measure the temperature of the oil and the water with a thermometer. Record.
5. Remove the oil from the hot plate.
6. Continue heating the water until it reaches the same temperature as the oil and then
remove the water from the hot plate.
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7. Record the temperature of the oil and the water every 5 minutes for 15 minutes.
Results:
It took the water much longer than the oil to reach 180 degrees F. and it took the
water much longer than the oil to cool down again.
a. Based on the above results what might you conclude about water?
b. What might you infer about the following?
-Living things have large quantities of water in their systems.
-Earth is 75% covered with water.
- The majority of living things are aquatic.
-Evaporation of sweat cools our bodies.
PART M: OPTIONAL IF TIME PERMITS
Material; Paper cup, paper clips, paper towel
1. Place a plastic cup on top of a paper towel
2. Fill the cup completely with water.
a. Predict how many paper clips you can put into the cup before the water
spills over. Record your prediction.
3. Gently add paper clips one at a time.
a. Record the # of paper clips required to spill water over the top of the cup.
b. What properties of water were demonstrated?
PART N:
1. After doing all these experiments, can you explain the following terms?
a. Polarity
b. Hydrogen bonds
c. Cohesion
d. Adhesion
e. Surface tension
f. Capillary action
g. Specific heat
h. Expansion of water
i. Water density (liquid) Vs. ice density (solid)
k. Hydrophilic
l. Hydrophobic
m. Solvent
n. Solute
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