Evaporation and Temperature Change

Dorian J. Price                Horatio May Academy
                               512 South Lavernge
                               Chicago IL 60644
                               (312) 534-6140

Objectives:

1.  This objective is focusing on the intermediate level.  The students will 
    learn how temperature is related to evaporation.
2.  The students will learn scientific terms related to the experiment.
3.  The students will compare how much heat is required for various substances 
    to evaporate by measuring how much the surrounding temperature decreases. 

Materials Needed:

1. Thermometer
2. Several balls of cotton
3. Small samples of acetone, isopropyl alcohol, water, and perfume
4. Hot plate 

Strategy:

1. Twist the mercury-bulb end of the thermometer into a cotton ball to make a 
   giant cotton swab.
2. Place the thermometer with the cotton ball on the desk and prop up the cotton 
   ball end with a pencil so that it does not touch the desk top.
3. Note and record the temperature of the thermometer.
4. Add enough alcohol to wet the cotton ball (about 10-15 drops).
5. Watch the thermometer to see if a change in temperature occurs.  Note the 
   lowest reading on the thermometer.  Record your results.
6. Allow the thermometer to return to room temperature.
7. Using new cotton balls, repeat with acetone, isopropyl alcohol, water, and 
   perfume.

Performance Assessment:

The students will be given an exam consisting of terms and questions related
to the process and results of the experiment.  Prior to the exam, there will be 
an oral discussion to evaluate the level of comprehension.  The students will 
master how temperature is related to evaporation with 100% accuracy. 
  
References:

Chemical Activities: Teacher Edition

Notes for the Teacher:
SAFETY: Acetone, alcohol, and perfume are flammable.  Extinguish all flames in 
the room.
1. Provide samples of several liquids. Use small quantities to minimize hazards.
2. Stress data gathering and record keeping in this activity.
3. Be careful with thermometers.  They are easily broken.  If a mercury 
   thermometer breaks, collect all the mercury and store it in a labeled, sealed
   container.