Properties of Water Exploration

Station 1:

Polar~ opposite ends, opposite charges

1. Please draw a model of a molecule of water and label the areas of positive and negative charge.

2. Rub the balloon on your head and build up a lot of static charge. It is better to use someone’s hair that doesn’t use a lot of product. Now, with the pipette, squirt a stream of water near (not on) the balloon. What do you notice happening?

3. Please explain your observation in terms of the chemistry behind water.

Station 2:

Cohesion~ H+ bonds holding the same type of molecules together

1. Predict: Can you put more drops of regular water or more drops of soapy water on a penny? ___________________

2. Using a pipette, place as many drops of regular water on the penny as possible. _________

3. Dry and repeat. __________

4. Draw a side-view sketch of what your penny looked like just before the water fell off.

5. Wash your penny with faucet water, then dry and repeat with soapy water. ________

6. Dry and repeat. _________

7. Wash your penny with faucet water and then dry.

8. Sketch a bar graph of your data.

9. Please come up with a scientific explanation for your results. Hint…Soap contains a lot of hydroxide ions.

Station 3:

Density~ ratio between a substance’s mass and its volume (D=m/v)

1. Given the fact that the density of water is 1g/mL, that objects with a density of less than 1g/mL float, and those with a density greater than 1 sink, what do you know about the density of ice?

2. Would 1 gram of ice take up more space or less space than 1 gram of liquid water? Explain how you would know this. Hint…think about putting a water bottle in a freezer.

3. Write a short paragraph about how the world would be different if ice had a density of 1.1g/mL.


Station 4:

Adhesion~ H+ bonds holding molecules to another substance + Cohesion + Polarity

1. Use a pencil to label four strips of chromatography paper as follows: SW (Sharpie + Water), SIP (Sharpie + Alcohol), CW (Crayola + Water), CIP (Crayola + Alcohol). Label them at the very top of each strip.

2. On the other end of each strip make a horizontal line straight across the width of the paper. Use a black Sharpie Marker for two of them and a black Crayola marker for the other two. Make sure that your mark is about 2cm from the base of the paper.

3. Wrap the top (with the codes) of each strip around a pencil. Tape it in place. Put the two that go in water together on the same pencil and the two that go in alcohol on the same pencil. Make sure that they hang at about the same length.

4. From the supply table, get 1 container for water and 1 container for 91% isopropyl alcohol. Place enough of each of these substances in the containers such that about 3mm of the chromatography paper comes in contact with the paper.

5. Let this experiment sit for about 10 minutes.

6. On your answer sheet, please draw what you see on each of the strips of paper.

7. Using what you know about the polarity of water, make a prediction about the polarity of the two types of ink and the polarity of isopropyl alcohol.

8. How is the principle of cohesion being demonstrated in this lab?

9. How is principle of adhesion being demonstrated in this lab?

Station 5:

Specific heat~ amount of heat absorbed or lost to change temperature by 1°C

1. We placed two beakers outside for the same amount of time (~1 hour) in direct sunlight.

2. One beaker contained air and the other contained water. The temperature of the air increased from 20°C to 43°C and the temperature of the water increased from 24°C to 33°C.

3. Create a data table that summarizes this data. You should also include a column entitled “Change in temperature”.

4. Create a bar graph that represents the changes in water temperature.

5. Given the results of this experiment, the data, and the definition of specific heat, which has a higher specific heat? Please explain your answer.

6. Now, pretend that we heated the air and the water up to 80°C and then let them sit for 1 hour in a room that was 20°C. Predict what the thermometers in each beaker would read. Please give a reason for your answer.

Station 6:

Heat of vaporization~ quantity of heat required to convert 1g from liquid to gas states

1. Using a pipette, place a drop of water on the top of your left hand and using a different pipette, place a drop of isopropyl alcohol on your right hand.

2. Gently blow on each drop.

3. Record what you feel on each hand.

4. Does water or isopropyl alcohol have a higher heat of vaporization? Please explain your answer.

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