Evaporation Exploration
from
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ou’re geared up and ready to play. Wait! What are you wearing? Fabrics like cotton can soak up sweat and water, and they dry slowly. So as you sweat, cotton clothes can become wet and sticky, even heavy—they hold on to the water they soak up. The new high-tech fabrics in modern sports clothing are different. They have the ability to pull moisture away from the skin and carry it to the outer surface of the clothing, where it can evaporate more easily and cool you off. In the following activity, you will compare the rate of evaporation of water from cotton and a paper towel, which will act like a high-tech fabric. Be sure to follow Milli’s Safety Tips and do this activity with an adult! Do not eat or drink any of the materials used in this activity. SAFETY!
Materials Permanent marking pen Small cup Hot tap water
Roomtemperature water 4 zip-closing plastic bags, quart size
2 droppers 2 brown paper towels 2 pieces of 3” x 3” cotton fabric swatches
Celebrating Chemistry
Procedure 1. Use a marking pen to label the cup “Water”. 2. Use the marking pen to label 2 zip-closing bags with “Room Temp”. Label the other 2 bags with “Hot Water”. 3. Add about 1 cup of room-temperature water to each of the 2 zip-closing plastic bags labeled “Room Temp”. Get as much air out as possible, and seal the bags securely. Lay the bags down flat. 4. Have your adult partner add about 1 cup of hot tap water to each of the 2 zip-closing plastic bags labeled “Hot Water”. Get as much air out as possible, and seal the bag securely. Lay the bag down flat. This bag will serve as a heat source. 5. At the same time, use a dropper to place 1 drop of room-temperature water in the center of 2 separate pieces of brown paper towel. 6. Repeat step 3 with the cotton fabric swatches. 7. Allow the drops to spread for about 10-20 seconds until they don’t seem to spread any more. 8. Place one paper towel on the bag labeled “Room Temp”. Place the other paper towel on the bag labeled “Hot Water”. 9. Repeat step 8 with the cotton swatches. 10. Observe every few minutes. Compare the amount of water on each paper towel in the “What Did You Observe?” section. 11. Thoroughly clean the work area and wash your hands.
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Evaporation Exploration page 2
Wa te r
Room temp Room tewmapter water
What Did You Observ e
Does adding heat to water increase the rat e of evaporation? ________________ ________________ ____ ________________ ________________ ____ Which sample of wa ter evaporated faster , the cotton swatch or the paper towel? ________________ ________________ ____ ________________ ________________ ____
Hot water Hot water
Where’s the Chemistry?
The fabrics used in modern sports clothes have pores to move water away from the skin and to the outer surface of the fabric so that it will not soak up. The pores provide a way for sweat to evaporate faster, keeping you dry and comfortable. Evaporation happens when water is heated and goes into the air. It takes energy to evaporate water. Heat is a form of energy, so water evaporates more quickly at warmer temperatures. The material that soaked up the water will have a slower rate of evaporation versus the material that contains pores for the water to easily evaporate, just like what is used in high-tech clothing.
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Science Activities for Kids
T
he American Chemical Society develops materials for elementary school age children to spark their interest in science and teach developmentally appropriate chemistry concepts. The Activities for Children collection includes hands-on activities, articles, puzzles, and games on topics related to children’s everyday experiences. The collection can be used to supplement the science curriculum, celebrate National Chemistry Week, develop Chemists Celebrate Earth Day events, invite children to give science a try at a large event, or to explore just for fun at home. Find more activities, articles, puzzles and games at www.acs.org/kids.
from the American Chemical Society
Safety Tips This activity is intended for elementary school children under the direct supervision of an adult. The American Chemical Society cannot be responsible for any accidents or injuries that may result from conducting the activities without proper supervision, from not specifically following directions, or from ignoring the cautions contained in the text.
Always: • Work with an adult. • Read and follow all directions for the activity. • Read all warning labels on all materials being used. • Wear eye protection. • Follow safety warnings or precautions, such as wearing gloves or tying back long hair. • Use all materials carefully, following the directions given. • Be sure to clean up and dispose of materials properly when you are finished with anactivity. • Wash your hands well after every activity.
Never: • Never eat or drink while conducting an experiment, and be careful to keep all of the materials used away from your mouth, nose, and eyes! • Never experiment on your own!
For more detailed information on safety go to www.acs. org/education and click on “Safety Guidelines”
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