Gabe Mystery of water Demo

Properties of Water Mini-Lab Activities (50 points)

Objective: Water is everywhere. It makes up about three quarters of the surface of the earth. It makes up 50-95% of the weight of living organisms. It is in the air we breathe, the sinks we use and in every cell of the body. Water has special properties that make it unusual and complex. For instance, think about what water can do by answering these questions:

1. How does water rise from the roots of a tree to the very top? (2 points)

The water climbs the roots of a tree with the capillary effect, adheres to the walls and climbs

2. How do insects walk on the water? (2 points)

Insects walk on water by using the waters surface tension 

3. Why does ice float rather than sink? (2 points)

Ice is a lower density than water so it floats

4. Why do people become seriously ill, or die, if they go without taking in water for more than a few days? (2 points)

The human body cannot survive without 90% water.

5. How would life in a lake be affected if ice sank and lakes froze from the bottom up? (2 points)

There would be less room in the lake the fish would have to swim at the top

Water has the ability to be a liquid, solid or gas depending on the temperature at which it

is found. Each molecule of water is made up of 2 hydrogen atoms and 1 oxygen atom bonded together.

Water is attracted to other water molecules like magnets. This is called cohesion.

Part 1

Materials:

Penny

Water

Medicine Dropper

Graduated Cylinder

Methods:

1. Obtain a medicine dropper and a small graduated cylinder. Make sure the dropper is clean.

2. Using the dropper, count how many drops it takes to get 1 mL in the graduated cylinder.

3. How many drops, of the size produced by your medicine dropper, are in each cubic

centimeter (cc) of water? (1 cubic centimeter = 1 milliliter) 12drops
(2 points)

4. Conversely, how much water is in each drop? (divide 1cc by the number of drops)

1/12 cc. Per drop, on average. (2 points)

5. Predict how many drops you will be able to put on the penny before it overflows by having each person at your table guess before you carry out the experiment.

Person 1 Person 2 Person 3 Person 4

10            7              9              12

Average of the guesses of the four people = 9.5 drops  (2 points)

6. Now, lets see how many drops of water you can place on the surface of the penny before it overflows. Drop water from the dropper onto the penny, keeping a careful count of each drop.

7. Draw a diagram in the margin to the left showing the shape of the water on the penny after one drop, when the penny is half full, and just before it looks like it is going to overflow.

(Record # of drops: Single Drop; Half Full 20 drops; Near Overflowing 40 drops
(2 points)

8. How many total drops did you get on the penny? 52  (2 points)

9. If the number of drops is different from your prediction, explain your results in terms of cohesion.

The water maintains surface tension so it stays in a bubble and can keep getting added to even after it has overflowed

Materials:

Penny

Water

Medicine Dropper

Detergent

Methods:

1. With your finger, spread one drop of detergent on the surface of a dry penny.

2. How many drops do you think this penny will hold after being smeared with detergent?

Person 1 Person 2 Person 3 Person 4

20            7              20            23

Average of the guesses of the four people = 17.5 drops  (2 points)

3. Using the same dropper as before, add drops of water to the penny surface. Keep a

careful count of the number of drops, and draw pictures as before using the margin to the left.

Single Drop Half Full 3 drops Near Overflowing 6 drops  (2 points)

4. Did the detergent have an effect on the outcome?
Yes, the detergent broke the waters surface tension so it didn't take on as many drops (2 points)

5. How does the detergent affect the water?
The water molecules are attracted to the charged end of the detergent and are attracted outward this interferes with the inward pull of the surface tension (2 points)

6. Explain how detergents act as cleaning agents. Use the terms cohesion and surface tension in your explanation.

Detergents are attracted to water on one end and attracted to greasy substances on the other so that it grabs the grease and holds onto the water

(2 points)

Part 3

Materials:

Penny

Water

Glass Slide

Medicine Dropper

Wax Paper

Methods:

1. What will the shape of water be on a piece of wax paper and a glass slide? Draw your

prediction.

Wax Paper  (2 points) Glass Slide  (2 points)

2. Perform the experiment. Place several drops of water on each surface and draw the

results below.

Wax Paper  (2 points) Glass Slide  (2 points)

3. Explain what happened.

the water adhered to the water and didn't adhere to the waxpaper

Part 4

Materials:

Water

Chromatography Paper Strip OR paper towel strip

Stop Watch

Graduated Cylinder

Blue or black felt tip marker

Methods:

1. How fast do you think that water will climb up a piece of absorbent paper about 1 cm wide?

One cm per (30sec) (2 points)

2. Obtain a 50 ml graduated cylinder, and cut a strip of paper towel that is just long enough to hang over the side of the cylinder (inside) and reach the bottom.

3. Place a single drop of ink from a marker on the paper about one cm from the

bottom and let it dry.

4. Place 10ml of water into the graduated cylinder and place the strip of paper in the cylinder so the bottom first cm is immersed in water and the drop of ink is just above the surface of the water. Fold the paper over the top of the graduated cylinder.

5. Note the starting time

6. Note the height of the water at 30-second intervals and make a mark on the graduated cylinder to know where the water was at that time. When water climbs to the tip of the paper, remove it and let it dry.

Time Distance (2 points)

30 12

60 15

90 17

120 18

150 20

180   21

7. How did the ink change? (2 points)
the dot grew bigger, it climbed up the paper and the water turned green

8. Why did this occur (think about plants and capillary action)? (2 points)

the fibers in the paper create tiny pockets and the dye goes into them and spreads

Part 5 – Pulling it all Together

1. List three things that you discovered about water? (3 points)

that it is highly cohesive
hydrogen bonds are weak alone but when there's a lot it's pretty strong.
water can climb  surfaces even when they are not submerged

2. How do the characteristics of water allow the human body to function as it does? (3 points)
blood is mostly water and the water travels through veins and arteries supplying oxygen to our brain.