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

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?

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?

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?

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

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

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

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

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?

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?

Starting temperature What is the starting temperature of your thermometer?

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

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.

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

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

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

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?

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

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.

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?