Evaporation Lab

Materials:
Lamp
Fan
Single beam balance (2 parts)
2 solid pieces of sponge
1 sponge cut into to three sections
Open mouth jar

Evaporation is the process by which water turns into its gaseous form (water vapor). Temperature, humidity, air movement and surface area are all factors that affect the process of evaporation. You will investigate the affect of each on evaporation by comparing evaporation of sponges. You will balance two wet sponges, add the variable, and time how long it takes the sponges to get out of balance. This change in balance may be small and slow. 

Assemble the balance

Temperature
1.  Wet two of the solid sponge pieces and squeeze them just enough so they do not drip. 
2. Push one sponge through each of the hooks and adjust the beam until it is balanced.
3. Place the lamp next to one of the sponges and keep time until the sponges are no longer in balance.
4. Record the results.

Humidity
1. Moisten two solid sponges and place on the hooks of the pivot beam. Balance the beam
2. Let one of the sponges hang into an open-mouth jar, not touching or rubbing against any portion of the jar.
3. Allow the sponges to stand and keep time until they are no longer in balance. Record the results.

Wind
1. Wet two solid sponges and place them on the hooks of the pivot beam. Balance the beam.
2. Direct a gentle air current from the fan on one of the sponges, being careful to cause as little movement of the beam as possible. 
3. Keep time until the beam is no longer in balance.
4. Record the results.

Surface Area
1. Wet one solid sponge and one segmented sponge.
2. Place them on the pivot beam and bring them into balance.
3. Keep time until the beam is out of balance. Record the results.

Evaluation Questions
1. Why did the sponge move in each of the tests?
2. How could someone distinguish between a greater or lesser rate of evaporation on the sponge being tested?
3. Did any variables appear to have a greater effect on evaporation rate than the others?
4. How does temperature affect evaporation?
5. What effect does the jar have on the humidity of the air around the sponge? Why?
6. What effect does humidity have on the rate of evaporation?
7. What effect do air currents have on evaporation?
8. What effect did slicing the sponge have on the surface area of the sponge?
9. How does surface area affect evaporation? Why?
10. Using the conclusion on surface area, when might evaporation over the ocean be greatest? During times of choppy waves or calm water?
11. Based on the effects of temperature, humidity, air currents, and surface area in regard to evaporation, relate how these concepts are applied by man in an ordinary electric clothes dryer.

Cloud formation lab

Have you ever walked through fog? What does it feel like? If you have walked through fog, you have walked through a cloud. Clouds will only form under certain conditions. You have to have water vapor present and some kind of particle in the air for water vapor to condense on. 

Materials:
2 liter pop bottle - clear
Smoke (match)
Warm water
Thermometer

1. Pour a small amount of warm water into the bottle. 
2. Place the thermometer in the bottle so you can see it.
3. Light the match, blow it out and capture some of the smoke in the bottle. 
4. Cap the bottle immediately after getting smoke in the bottle.
5. Squeeze the bottle. Then release it. Do this several times and observe what is happening in the bottle.
6. Answer the following questions:
a. As you squeeze the bottle, what is happening to the air pressure?
b. What is happening the minute you release the bottle? What is the air doing?
c. What is the air pressure like when you observe the cloud?
d. What is happening to the temperature when you squeeze the bottle? Why is this happening?
e. Write a summary of cloud formation. Include what a cloud is, how a cloud forms and what conditions are needed for formation.