Properties of Water
Lab Exercise
Introduction: Water is a simple molecule, yet it’s the most vital to all living things. Unique properties of water enable it to carry out
functions that no other substances can. In a neutral aqueous solution, five molecules of water can be seen bonded together by weak
hydrogen bonds. Furthermore, due to the negativity of oxygen in the molecule and a slight positive charge to the hydrogen atom,
water is a polar molecule. Due to its polarity, water is classified as the universal solvent. You will investigate these major properties
of water and others throughout this lab.
Part One: Polarity
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Label the diagram based on the reading from page 40 in your textbook. Make sure you label the oxygen, hydrogen (2),
and polar charges.
How does polarity affect the water molecule?
Solutions, Solvents and solutes
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Put 300ml of H2O into your beaker
Bring the beaker to my counter and measure out 10g of NaCl
Dissolve 10g of NaCl in a beaker of water. Stir until it is completely dissolved.
Time how long it takes to dissolve completely
How long did it take?
Which is the solvent?
Which is the solute?
What is the resulting solution?
Describe another polar molecule that dissolves easy in water.
Part Two: Hydrogen Bonding, Expansion on Freezing, Specific Heat, Evaporative Cooling
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See me to get room temp water in your Styrofoam cup
Record the temperature reading before dipping the probe into the styrofoam cup of H 2O
Dip your temperature probe into the Styrofoam cup of room temperature water
Fold a piece of paper into a fourths and gently fan the probe
What happened to the temperature?
Describe how this property is important to you on a hot day?
Design your own experiment
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Water expands when it freezes. Describe a test that you could complete at home to prove water expands as it freezes.
What materials did you use?
What would you expect to happen?
Why does ice float?
Part Three: Adhesion, Cohesion, Surface Tension, Capillary Action
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Water forms very cohesive bonds that can sometimes defy gravity. In this demonstration, you will predict how many
drops of water will fit on a penny before it spills over and repeat. Repeat the experiment again with your sodium chloride
solution.
Use the water from your Styrofoam cup and the pipette for the plain water trial
Use the water from your beaker for the NaCl trial
Use care in placing the drops in order to get the maximum output.
After your trials come up with three questions and answers for this experiment.
Plain water
Predicted Drops =
Actual Drops =
NaCl Water
Predicted Drops =
Actual Drops =
Plain water
Predicted Drops =
Actual Drops =
NaCl Water
Predicted Drops =
Actual Drops =