Water Properties 2009
Introduction:
Water has unique characteristics that make life on Earth possible. The emergent properties of
water that are essential to life as we understand it ultimately result from the relative
electronegativity of oxygen and hydrogen atoms and the resulting polarity of the molecule. You
will explore some of these properties, then design and conduct a series of simple experiments
of your own.
Part 1: Explore.
Try the two activities described below. Notice the variables and suggested additional conditions
included for each. Record qualitative data for each condition tested.
A. Question: Are you attractive?
Independent variable: proximity of a human finger
Dependent variable: movement of water
Place a drop of water on a small piece of aluminum foil. Carefully place your finger on
the aluminum foil just next to the water drop. Allow the water drop to touch your finger.
Carefully move your finger away from the drop.
What happens?
Would you get the same result on the other side of the foil, or on wax paper? Try it.
B. Question: Does pepper avoid soap?
Independent variable: presence of a surfactant (soap)
Dependent variable: movement of pepper in water.
Place some water in one half of a petri dish. Sprinkle some pepper on top of the water.
Add a drop of soap to the center of the dish.
What happens?
Would you get the same result with salt? Try it.
Part 2: Design your own.
For each property below, design a simple test to answer each question. Identify independent
(what you are changing) and dependent (what changes as a result) variables and at least two
conditions to test. Construct a data table to record quantitative data where possible. Record
qualitative data for all experiments.
1. Property: Cohesion
Question: How many drops will fit on a penny?
Possible Materials:
Coin, Pipette, Water, Oil, Soap
Independent variable:
Dependent variable:
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HL/SL IB Biology| Mrs. Leto HHS
Water Properties 2009
Data:
2. Property: Adhesion
Question: Does water roll or slide?
Possible Materials:
Water, Wax paper, Aluminum foil, Glass slide
Independent variable:
Dependent variable:
Data:
3. Property: Surface tension
Question: How many paper clips will it take to break the surface tension?
Possible Materials:
Water, Soap, Paper clips, Paper cups
Independent variable:
Dependent variable:
Data:
Analysis: Explain your observations using what you know about the emergent properties of
water and its polar nature.
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HL/SL IB Biology| Mrs. Leto HHS