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Lab: The Properties of Water Name: _________________________

Water covers about 75% of the Earth’s surface. Water also composes 50 to 95 percent of the weight in all living organisms. It is one of the simplest yet most important molecules in living systems. Water is literally involved in every facet of life.

You have learned about water’s polarity and hydrogen bonding. Write a simple definition, in your own words, for each of these terms.

1. Polarity: _________________________________________________________________________________________

2. Hydrogen Bond: __________________________________________________________________________________

Now you will perform or observe a series of simple experiments in order to discover the various properties of water caused by polarity and hydrogen bonding. After Experiments 1-7, consult your notes and select the property of water that best describes what you have just observed. Be sure to provide an explanation as to WHY you chose that property of water.

Experiment 1: Place 1-2 drops of water on a small piece of wax paper. Using a clean toothpick, insert the end into the droplet and try to “move” the droplet around. Draw an eye level view of what you see in the space below.

Property of Water: __________________________________________________________________________________

Explanation: _______________________________________________________________________________________

Experiment 2: Place a small pinch of pepper to the top of a cup of water. Draw a bird’s eye view of what you see in the space below.

Property of Water: __________________________________________________________________________________

Explanation: _______________________________________________________________________________________

Experiment 3: Observe paper chromatography as a demonstration. Draw a sketch of the chromatography paper’s water level before it was placed into a glass of water and after the process is complete.

Property of Water: __________________________________________________________________________________

Explanation: _______________________________________________________________________________________

Experiment 4: Observe 1-2 drops of liquid dye being added to a glass of water. Draw 2 beakers of water below. Illustrate the dye in water when first added and then what it looked like after 2 minutes.

Property of Water: __________________________________________________________________________________

Explanation: _______________________________________________________________________________________

Experiment 5: As part of a class experiment, heat a beaker of sand and a beaker of water using a hot plate set to low/medium heat. Record the temperature of the beakers, using the procedure described by your teacher, every five minutes until each group in the class has taken a measurement. Copy the class data table in the space below:

Property of Water: __________________________________________________________________________________

Explanation: _______________________________________________________________________________________

Experiment 6: Place 1-2 drops of water on a paper napkin and observe what happens to the “droplet”.

Property of Water: __________________________________________________________________________________

Explanation: _______________________________________________________________________________________

Experiment 7: Think about what happens to an unopened plastic bottle of water that is left in the freezer.

Property of Water: __________________________________________________________________________________

Explanation: _______________________________________________________________________________________

**Now that you have attempted to identify the properties of water, work with your appointed partner(s) and write a definition to EACH of the seven properties of water IN YOUR OWN WORDS. Submit your group’s definitions to the teacher BEFORE you complete Experiments 8-10 **

Experiment 8: Dip your toothpick in the liquid detergent and gently touch the water droplet on wax paper. Draw the droplet before and after in the space below.

Experiment 9: Using the same toothpick from above, gently touch the top of the water with a pinch of pepper. Draw a bird’s eye view of the surface before and after in the space below.

Experiment 10: As a demonstration, observe as oil and water are mixed. After wards, observe what happens when liquid detergent is added to the mixture.

In experiments 8-10, detergent or soap was used. In your own words, describe how detergent affects hydrogen bonding and thus, the properties of water.

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WATER EXIT ACTIVITY Name:

Answer the questions below as a summary of what you learned in class MOD:

1. If there was a grease fire in a kitchen (grease is an oil based product), decide if you would put it out using water or flour. Support your decision with evidence from your experiments.

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2. All living things need to transport molecules from one place to another in order to carry out necessary life functions. Living things often transport these molecules by dissolving or dissociating them in water and then moving the resulting solution from place to place. What characteristic must a molecule have for it to form a solution in water?

A. It must be at least as small as the polar water molecules.

B. It must contain hydrogen or oxygen to bond to part of the water molecule.

C. It must be at least slightly polar to be able to react with the polar water molecule.

D. It must be covalently bonded in order to form new bonds with the polar water molecules.

3. Water is essential for life. Its special properties make water the single most important molecule in plant life. Leaves are unable to absorb water during irrigation or during precipitation, and must depend on the root system of the plant to absorb water. The xylem is the vascular tissue that moves the water from the root system to the leaves to ensure water is present to function as a reactant for the process of photosynthesis. The picture below shows the process of water moving from the roots to the leaves.

[pic]

Which of the following properties of water enables it to move from the roots to the leaves of plants?

A. Water expands as it freezes

B. Water is an excellent solvent

C. Water exhibits cohesive behavior

D. Water is able to moderate temperature

4. Would it be possible for hydrogen bond to occur between water molecules if the molecules were not polar? Explain.

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5. The polarity of water allows for hydrogen bonds to occur. A single hydrogen bond is not very strong but there are approximately 1,390,000,000,000,000,000,000 hydrogen bonds in every drop of water. This allows for an increase in surface tension as the volume of water grows. Using your knowledge of hydrogen bonds, explain why even though both processes put your entire body in a pool, belly flopping is much more painful than diving.

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