Name
Properties of Water Lab
Block
Directions: Please record all of your answers regarding the properties of water lab on this lab
report sheet.
Introduction:
Water is all around you - an incredibly important molecule in biology! It’s in the air that you
breathe and in the majority of liquids that you drink. Water makes up between 67-70% of our
body, allowing our cells to be able to effectively process a variety of chemical reactions quickly
and efficiently. All life depends upon the unique features of water which result from its polar
nature and ‘stickiness’. Some of the unique properties of water that allow life to exist are:
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It is less dense as a solid than as a liquid.
It sticks to itself – cohesion – cohesion is also related to surface tension.
It sticks to other polar or charged molecules – adhesion – adhesion results in
phenomena such as capillary action.
It is a great solvent for other polar or charged molecules.
It has a very high specific heat (heat of fusion and heat of vaporization) – that is,
it can absorb a great deal of heat energy while displaying only small increases in
temperature.
Water is a polar molecule. The oxygen atom in water has a greater electronegativity, or a
stronger “pull” on the electrons that it shares with the two hydrogens it is covalently bonded
to. As a result, the molecule ends up having a partially negatively charged end, near the oxygen,
and a partially positively charged end near the hydrogens – much like a magnet. Much like a
magnet, opposite charges will attract and likes will repel, so that the slightly negatively charged
oxygen of one water molecule will be attracted to the slightly positively
charged hydrogen of a neighboring water molecule. This weak attraction
and “sticking together” of polar molecules is called hydrogen bonding.
Each water molecule has the ability to attract to four different water
molecules at one time, and this continues on, creating a globular shape.
(Introduction has been modified from
https://www.lsrhs.net/elenbaasp/Sites/Biology/Biochemistry_files/waterlabbio2.pdf)
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Pre-lab questions
1. What makes water a polar molecule?
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2. Label a hydrogen bond and a covalent bond in the water molecule.
3.
4.
5.
6.
Is water polar or nonpolar (circle correct answer)?
Is oil polar or nonpolar (circle correct answer)?
List a substance that is hydrophobic? _____________________
Why is water considered the universal solvent?
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7. Name at least three solutes in your body.
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Station 1- Polar or Nonpolar
Step 2 Observation:
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Step 4 Observation:
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Step 5 Observation:
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Step 6: Is oil or water a better solvent? How do you know?
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Step 7 Observation:
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Step 8- Answer the questions:
Think about what you observed; can you relate what you observed to anything that may occur
in nature? How could this relate to an oil spill in the ocean? How could this affect an
ecosystem?
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Station 2- Surface Tension: The Petri Dish & the Pepper
1. Why does the pepper float? _______________________________________
2. Record your observation. Why do you think this happened?
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Station 3- Paperclip Madness
1. Record the number of paper clips you were able to get to float. ___________
2. Which property of water did this represent?
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Station 4- Capillary Action
1. How did the ink change?
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2. How long did it take for the water to climb to the top? Did it take 25 minutes or longer?
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3. Record your data in the table below. Make a line graph to represent your data.
Time
(min)
0
5
10
15
20
Distance
(cm)
Station 5- What’s the pH?
Step 1- Predict what you think the pH will be for each substance.
Step 2- Record the actual pH from the pH indicator paper for each substance.
Substance
Predicted pH
Actual pH level
Is it an acid /
level
neutral / base
Windex
Lemon Juice
Distilled Water
Vinegar
Orange Juice
Coffee
409 disinfectant
Apple Juice
Pickle juice
Laundry detergent
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Use your notes to answer these questions.
1. What does pH mean?
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2. What is the difference between acids and bases?
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3. Draw a pH scale on the line below that represents the substances you tested above.
4. Describe the relationship between hydrogen ions and pH.
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5. Compare the hydrogen ion concentrations in vinegar to Windex.
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Station 6- The Density of Water
Analysis: Use the three sets of mass and volume measurements to calculate three density
values for water (remember – you are measuring the mass; the volume should be 25mL each
time). Then take the average of these three density values. DENSITY = MASS ÷ VOLUME
Use units!!
Mass of H2O:
Trial 1 (25mL)-__________
Densities:
Trial 1-______________
Trial 2 (25mL)-__________
Trial 2-______________
Trial 3 (25mL)-__________
Trial 3-______________
What is the average of the three densities? ________________
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Station 7- Observing Capillary Action
Record the date and time below that you placed the flower or celery in the colored water:
Date:__________________
Time:_______________
Observation 1- Before you
leave class, record what you
see. Look at the cut end,
what do you see? Describe
and draw it.
Observation 2- Come back
tomorrow, record what you
see. Has anything changed?
Describe and draw it.
Observation 3- Day 3, record
what you see. Has anything
changed? Describe and draw
it.
1. What happened to the colored water? ____________________________________________
2. Did the colored water travel through all parts of the flower or celery? Explain.
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3. If the water traveled differently in different places, suggest a reason for the differences.
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4. What properties of water are responsible for these results?
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