1. Investigation 6 part 1 & 2 Water Vapor, Evaporation, & Humidity
Day 27
Investigation 6 part 1 & 2
Water Vapor, Evaporation, & Humidity

2. REVIEW OF WATER VAPOR What is water vapor? Can you see water vapor?
But you can see steam coming out of a boiling teakettle. Why is that?
Where does fog on bathroom mirrors come from? How does the dew on the outside of a glass of iced tea get there?

3. PROPOSED WATER VAPOR INQUIRY
Discuss the following questions with a lab partner.
1. Where does fog on the bathroom mirror come from?
2. How does the dew on the outside of a glass of iced tea get there?

4. REVIEW OF PART 1 Explain what your group did in part 1.
How do we know that in fact there is water vapor in the air from part 1?

5. Water Vapor Have good evidence for water vapor in the air
How does water vapor get into the air?

6. EVAPORATION Write the following definition in your notebook.
EVAPORATION - IS THE PROCESS BY WHICH LIQUID WATER BECOMES A GAS CALLED WATER VAPOR.

7. Water in the Air?
Dampen a small area on the back of both hands
Fill a cup half full of water
Gently blow on the spot on your left hand to simulate wind

8. Feel Cold? Heat is required to evaporate water
Energy transfers from hand to water by conduction
Reduced heat = cold signal to your brain

9. QUESTIONS (WIND) 1. What effect does wind have on the wet spot?
Where did the water go that was on your hands?
Why did the wet spots feel cold?

10. Procedure For each pair: Two thermometers One piece of fabric
One rubber band
Paper towel
Two pairs will share the cup of water
How could you use the materials to measure temperature change during evaporation?

11. Starting temperature
What is the starting temperature of your thermometer?

12. Procedure (con’t)
Wrap a piece of muslin around the bulb end of your 2 thermometers
Secure with rubber bands
Dip the muslin end of 1 thermometer into the water
Blot excess water from the muslin so that it is not dripping

13. Procedure (con’t)
How can you increase the amount of evaporation from the fabric?
Waving the fabric back and forth rapidly
Rest elbow on the desk
Wave your wrist back and forth
Take turns
Will shake for 5 minutes
Record data in a table.

14. TABLE WET 1. DRY THERMOMETER/ ORIGINAL TEMP. TEMP. @ 1 MIN

15. Results Final temperature? What caused the temperature to go down?
Remember:
Evaporation (liquid to vapor) requires energy
Energy = heat in the environment

16. Discuss Results
What happened to the water on the fabric when you waved the thermometer around in the air?
Water evaporated
When water evaporates from a surface, what happens to the amount of water vapor in the air?
It increases

17. DISCUSSION CONT. What is required for evaporation to happen?
Where did the heat come from?
When you take heat energy away from an object, does the object get warmer or colder?

18. DISCUSSION CONT.
What object or objects got cooler, when the water evaporated from the cloth?
Where did the heat energy go?

19. CONDENSATION
WATER CAN EXIST IN 3 PHASES OR STATES: SOLID ICE, LIQUID WATER, AND GASEOUS VAPOR.
WHEN WATER CHANGES FROM GAS TO LIQUID, IT IS CALLED CONDENSATION.

20. CONDENSATION WATER VAPOR CONDENSES TO FORM LIQUID WATER.
THE DEW ON CUPS OF ICE WATER IS WATER THAT CONDENSED FROM GAS TO LIQUID.
ARE THERE ANY OTHER EXAMPLES OF CONDENSATION YOU CAN THINK OF?