Living Environment
Student Work
Biochemistry Unit Lesson 7
Water
Name:
Period ______
Laboratory Experience
Worth 90 Lab Minutes
Date :
Bridge
Directions: Looking at a map or globe, answer the following questions:
1. What makes up most of the Earth?
2. What makes up most of our bodies?
3. Why is that?
4. How would a chemist write “water”?
Objective:
Identify
properties of
water that make
it so essential to
biological
systems.
Essential
Question:
What makes
water so
special?
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Living Environment
Student Work
Biochemistry Unit Lesson 7
Mini Lesson
Water has many properties that make it an extremely unique molecule and why most of the Earth
and our bodies are made up of it. In order to understand the properties of water, you must
understand the concept of an atom. Answer the following questions which are a review of atomic
structure, atoms, elements, and water that we have done previously. Discuss with your partner
before the class discussion:
1.
2.
3.
4.
5.
6.
What parts make up an atom?
Where are they located?
What causes an atom to be able to bond to another atom?
What are elements?
Which elements make up the water molecule?
What is polarity?
Expectations for Work Period:
 In pairs, you will be working at different stations to discover some things about water.
There is specific vocabulary words that you will need to know, but you are going to try to
determine the meaning of the words first.
 At each of the stations, follow the procedures given in your lab handout and answer the
questions asked. Use the questions and your observations to help you develop the
meaning of the vocabulary words associated with it.
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Living Environment
Student Work
Biochemistry Unit Lesson 7
Work Period
Stations: Check off as you complete each one!
Cohesion of Water
Adhesion
Surface Tension
1B Water and Oil
3A Drop Behavior – Water
on Penny
1C Water, Oil and Dye
3B Effects of Detergent
1D Sheen
3C Floating on Water
1A Water and Oil
Capillary Action
Station 1. Cohesion of Water
1A. Water and Oil
Predict: What will happen if you add cooking oil? (circle one below)
a. the oil will float on top of the water
b. the oil will sink to the bottom of the water
c. the oil will dissolve in the water
d. the oil will become mixed up with the water
e. other (what?)
Data: Explain what happened or what you observed as a result of the station directions
1B. Oil and Water
Predict: What will happen if you add water? (Circle one below)
a. the water will float on top of the oil
b. the water will sink to the bottom of the oil
c. the water will dissolve in the oil
d. the water will become mixed up with the oil
e. other (what?)
Data: Explain what happened or what you observed as a result of the station directions.
Analysis: Which is less dense (has less mass per mL): oil or water? How do you know?
1C. Water, Oil, and Dye
Predict: Predict what will happen if you add a few drops of a water-soluble dye solution to each
of the above graduated cylinders containing water and oil. Will the dye mix with the water, the oil,
or both?
Data: Describe how the dye behaves in each of the cylinders.
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Living Environment
Student Work
Biochemistry Unit Lesson 7
Compare your predictions and results. Explain any differences.
Predict: Will the contents remain mixed? Why do you think that?
Analysis: Observe what happens, compare with your prediction, and explain why it happens.
Your explanation should involve polarity, polar and non-polar molecules, solution, and hydrogen
bonding.
1D. Sheen
Predict: Take a clean beaker of water. Predict what will happen if you add one small drop of oil
to the water using a pipette.
Analysis: Can you see the oil? What your prediction correct? (Add more drops of oil if
necessary to see clearly). Describe.
Predict: What will happen if you add a drop of detergent to the beaker?
Data: What happened?
Analysis: Compare the results with your prediction and explain how the detergent works in
molecular terms.
Extension: Explain some of the consequences of oil spills in the sea. What effects do they have
on sea life and bird life, and what methods are used to “clean up” oil spills.
Station 2. Adhesion
Predict:: What will the drop of water look like
Wax Paper
Glass
Why did you predict this? What assumptions are guiding your thinking?
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Living Environment
Student Work
Biochemistry Unit Lesson 7
Data: Draw what it actually looked like:
Wax Paper
Glass
Analysis: Compare with your predictions with your data and explain.
Define: This demonstrates a concept called adhesion (based on hydrogen bonds). What do you
think adhesion means?
Station 3. Surface Tension
3a. Drop Behavior- Water on a Penny
Initial Observations: How many drops in 1 mL of water? ______ drops
Calculate: How much water is in each drop? (divide 1cc by the number of drops) ____ cc per
drop.
Predict with your Group:
Table 1. Numbers of Drops Predicted
Person #1
Person #2
Person #3
Person #4
Total 1-4
Calculate Average
Data Collection:
Figure 1. Drawing of Drops
Single Drop
Half full: _____ drops
near overflowing: ____ drops
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Living Environment
Student Work
Biochemistry Unit Lesson 7
How many drops were you able to place on your penny before it overflowed? _______ drops
Analysis: If the number of drops is very different from your prediction, explain why it is different.
If it is the same or very close, explain how you made such a close prediction, using your
knowledge of atomic structures and water molecules.
3b. Effects of Detergent
Predict: How many drops of water do you think the penny will hold after you put detergent on it?
Why?
Table 2. Numbers of Drops Predicted with Detergent
Person #1
Person #2
Person #3
Person #4
Total 1-4
Calculate Average
Data Collection:
Figure 2. Drawing of Drops
Single Drop
Half full: _____ drops
near overflowing: ____ drops
How many drops were you able to place on the penny before it overflowed this time? ____ drops
Analysis: Did the dish soap make a difference between the drops of the penny? Describe the
difference.
Evaluation: How does this compare to your prediction? Why do you think this happened?
What does the dish soap do to have this effect on water?
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Student Work
Biochemistry Unit Lesson 7
3c. Floating on Water
Follow the station directions.
Data Collection: How many tries did it take you to get it to float?
Evaluation: Explain why, even though the paperclip is more dense than the water, it was able to
float.
Define: These stations all demonstrate a property called surface tension that is also supported
by observations in station 1 (cohesion). Based on your observations and your definition of
cohesion, what do you think surface tension means?
Station 4. Capillary Action
Predict: How fast do you think water would climb a strip of absorbent paper about ½ inch wide?
1 inch/ ______ (time)
Data Collection:
Table 3. Time of Water Climbing
Time (minutes)
Distance (inches)
0
5
10
15
20
25
30
Analysis: How long did it take? How does this compare to your prediction?
What happened to the ink as the water moved up the paper? Why?
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Living Environment
Student Work
Biochemistry Unit Lesson 7
Attach your strip to this paper once it has dried.
How does capillary action relate to cohesion? To adhesion?
Class Data. Summarize the class results with respect to drops on a penny (3a and 3b). Report
your group’s average FROM THE DATA not the prediction.
Table 4. Number of Drops on a Penny.
Group
# Drops without Detergent
# Drops with Detergent
1
2
3
4
5
6
7
Average
Analysis: Explain the variation from group to group (why would they not all be EXACTLY the
same?)
Evaluation: What general conclusions can you draw from this class data?
Summary
What makes water so special?
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Biochemistry Unit Lesson 7
Closing
Describe at least one observation you have made that illustrates each vocabulary term below.
A. Polarity
B. Hydrogen bonds
C. Cohesion
D. Surface tension
E. Adhesion
F. Capillary action
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Living Environment
Student Work
Name:
Independent Practice
Biochemistry Unit Lesson 7
Period ______ Date :
Make observations of things going on around your home tonight. For each of the vocabulary terms,
come up with an example OUTSIDE the lab of where you observe these things happening.
a.
Polarity
b.
Hydrogen bonds
c.
Cohesion
d.
Surface tension
e.
Adhesion
f.
Capillary action
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