Water Mixtures and the Environment
Warning: Use lots of newspaper and make sure the kids know we are using charcoal not oreos!
Last week we talked about chemical reactions. Weíve been examining what happens when you mix familiar products to yield exciting results. This week we can carry that theme into an observation of water mixtures. Water, as an important part of life and the environment, is a precious resource. See the back pages for some fun facts.
Ask the kids:
Why is water important?
Water makes up about 55-75% of an adult's total body weight and is part of every body fluid. Nearly every function of the human body takes place in a watery medium. Water regulates body temperature, transports nutrients and oxygen to your cells, moistens body tissues, cushions joints and protects body organs and tissues. The body needs an ongoing supply of water Ė about 8-12 cups a day. Without it, dehydration can occur as well as loss of strength and endurance, heat exhaustion or even heatstroke under high temperatures. Also, animals, plants, cleaning, etc.
Demonstration: Making Polluted Rain
Gases and Liquids
Pot/pan: 2 if you use a burner, 1 if you use a hot pot
Burner or hot pot
Cup and spoon for mixing
Discuss the water cycle (a posterboard display of it may work well, or draw it on the board.). Where does water come from? Where does the rain go after it falls on the earth? Hereís some info on the water cycle: The water cycle is a process which consists of evaporation, transpiration, condensation, and precipitation. The whole process is controlled by the sun, which produces kinetic energy or heat energy. Evaporation occurs when the kinetic energy of the water molecules increases, causing the molecules to move more quickly, and undergo a liquid-to-gas phase change. Evaporation is stimulated by heat or sunlight. Transpiration is evaporation of water through the leaves of plants. The next part of the cycle is condensation and this is when gas molecules slow down, release energy, and turn into water molecules. Precipitation, is one form in which the condensed water molecules return to the earth (in the form of rain, snow, sleet, hail, fog, or dew). Most precipitation falls in either coastal areas or in high elevations. Some of the water which falls in high elevations becomes runoff water, the water which runs over the ground to lower elevations to form rivers, lakes, and fertile valleys. Sometimes this water collects nutrients from the soil it goes over making valleys fertile for plant growth.
See http://www-k12.atmos.washington.edu/k12/pilot/water_cycle/grabber2.html for a great diagram of the water cycle.
Younger and middle kids:Discuss evaporation and condensation, also liquids and gases. Talk about seeing your breath in the winter and drops forming on the outside of a cold drink. Have them come up with a list of different types of precipitation.
Older kids: Talk about transpiration in plants, possibly discuss energy (and gas vs. liquid) by having the kids be molecules.
Experiment 1: Filtering Foul Water
Density (of the whipped cream)
Plastic spoons (5)
Trash (paper scraps, gum wrappers, leaves, etc.)
Paper cups (small bathroom size)
Pen for making holes in cups
How does water get polluted?
Factory waste, burning forests, people throwing trash into lakes, oceans, rivers, etc.
When water gets polluted, what do scientists do to clean it?
Discuss which of the filtration methods we tried were best (which yielded the cleanest water, which are most feasible for large amounts of water). Older kids: Talk about kidneys as human water filters and why urine gets dark yellow when you are dehydrated (unless this discussion will generate trouble!).
What can we do to help our water supply?
Brainstorm! The kids will have probably have lots of ideas about how to conserve water, including: taking short showers, turning the water off in the house when youíre not using it, turning the water off while you brush your teeth, take baths instead of showers, etc. And of course, donít throw trash in bodies of water!
Experiment 2: Cleaning up an Oil Spill Victim
Remind the kids: We learned that oil and water donít mix. What happens when we try to mix oil with ocean water and living things dependent on water?
Styrofoam Ball/ Decorations
Bar of Soap
4 containers half-full of water
How does oil get into bodies of water?
Oil vessels with leaks, pipelines, oil well, storage tanks rupture in earthquakes, equipment failures, human error. Most oil spills in U.S. waters involve fewer than 100 gallons. There are 5000-7000 oil spills per year.
How does oil affect animals?
Spilled oil can damage fur and feathers, so animals are more likely to freeze and canít float as well. Oil is toxic--the animals may get sick from swallowing oil or inhaling its vapors. Animals that arenít directly contacted by oil spills can still be affected if their prey are exposed to oil. The animals may refuse to eat the oil-covered critters and starve, or eat them and get sick.
What happens to the oil once it is in the water?
Emulsification: Waves can cause the water and oil to mix together, and these mixtures sink and disappear from the surface. This gives the false impression that the oil is gone and the threat to the environment has ended.
Weathering: Winds, waves, and currents break down the oil (through both chemical and physical changes) from a slick into droplets that distribute throughout the water.
Evaporation: Lighter oils may evaporate (change from liquid to gas/vapor) and leave little residue behind in the water. Heavier oils leave a thicker, more viscous residue, which may have serious physical and chemical impacts on the environment. Wind, waves, and currents increase evaporation.
Biodegradation: Micro-organisms such as bacteria feed on oil. This works best in warm water environments. Nutrients (nitrogen, phosphorus) sometimes have to be added to the water to maintain the organisms.
What can scientists do?
Scientists try to contain the oil spill using barriers and materials such as gelling agents that stick to the oil and keep it from moving. Physical methods include wiping with materials that will absorb the oil, pressure washing, raking, and bulldozing. Scare tactics are used to protect birds and animals by keeping them away from oil spill areas. Floating dummies and helium-filled balloons are often used, particularly to keep away birds.
Younger and middle kids:Emphasize weathering and evaporation concepts, possibly omit biodegradation
Older kids: Emphasize emulsification (lesson 1) and biodegradation.
Experiment 3: Bubble Fun
Not all water mixtures are gross and harmful. Letís make one thatís lots of funÖ
Aluminum baking pans
This should be popular with the younger and middle kids, perhaps play a game with the older kids instead?
1. Water is the only substance found on earth naturally in the 3 forms; solid, liquid and gas.
2. It takes approximately one gallon of water to process a quarter pound of hamburger.
3. 39,090 gallons is used to manufacture a new car, including tires, per car!
4. 2,072 gallons of water is used to make four new tires.
5. Water acts as a natural insulator to regulate the earth's temperature.
6. A person can live more than a month without food, but can only last approximately
one week without water, depending on conditions.
7. In order to maintain health, a person must consume 2.5 qts of water per day from all
sources (water, food, etc.).
8. A birch tree gives off 70 gallons of water per day in evaporation.
9. A corn field of one acre gives off 4,000 gallons of water per day in evaporation.
10. The first water pipes in the U.S. were made from charred bored logs.
11. Two to seven gallons of water is used to flush a toilet.
12. The average five-minute shower consumes 25-50 gallons of water.
13. Two gallons of water is used to brush your teeth.
14. An automatic dishwasher uses 9-12 gallons of water to wash dishes, on the average.
15. Twenty gallons of water, on the average, is used to hand wash dishes.
16. The average resident uses 107,000 gallons of water per year.
17. An individual uses 123 gallons of water daily.
18. 80% of the earth's surface is water.
19. Of all the earth's water, 97% is ocean or seas.
20. One percent of the earth's water is suitable for drinking.
21. One gallon of water weighs 8.34 pounds.
22. It would take 219 million gallons of water to cover one square mile with one foot of water.
23. There are 7.48 gallons of water in one cubic foot.
24. When it rains one inch, you get 27,000 gallons of water per acre.
25. Water is the most common substance found on earth.
26. Water freezes at 32 degrees F, 0 degrees C.
27. 66% of the human body is water.
28. It takes 1,500 gallons of water to process one barrel of beer.
29. It takes 24 gallons of water to make one pound of plastic.
30. It takes 9.3 gallons of water to process one can of fruit or vegetables.
31. It takes 101 gallons of water to make one pound of wool or cotton.
32. It takes 1,851 gallons of water to refine one barrel of crude oil.
33. It takes 62,600 gallons of water to produce one ton of steel.
34. It takes 28,100 gallons of water to process one ton of cane sugar to make processed sugar.
This information was provided by the American Water Works Association of Denver Colorado.
Fun Facts About Water
Water has many purposes throughout the world, aside from human consumption and purposes related to that. With 70 percent of the earth's surface covered with water, it makes water the most common substance on earth. There are 326 million cubic miles of water on earth. Without water, there could be no life. Every living thing needs water to live, and every living thing is made of at least some water. For example, a chicken is about three-fourths water, and a pineapple is about four-fifths water. And as much as it is a part of each living thing, it has many uses inside and outside the home. It can irrigate dry farmlands in order to grow crops. (The United States uses 100 billion gallons of water for irrigation of crops per day.) We can cook with it, bathe with it, and use it to carry away wastes. On average, a human uses 70 gallons of water per day.
Water is very necessary to human life, and that fact is reinforced by the fact that humans take in
over 16,000 gallons of water during their lifetimes, with an average of 2.5 quarts per day. Water carries out life processes in everything, carrying out biological reactions and aiding with digestion of other nutrients. Water makes up almost 85% of our blood. The human body is made up of about 70% water.Water keeps our temperature correct. Water transports body wastes. Human beings can live much longer without food than they can without water.
The world's demand for water is constantly increasing, with no end in sight. Experts speculate
that by the year 2000, the world s need for water will double from what it was in the 1980s. And since only 3 percent of the water on earth is freshwater, and 97 percent of the water is trapped in glaciers, most of the water on earth is not easily available.
About 97% of the water on Earth is salt water and not suitable for drinking. Of the remaining 3% that is fresh water, about two-thirds is ice at the North and South Poles. Therefore, only 1% of the total water on Earth is liquid fresh water. Now, of the total liquid freshwater, about 98% is groundwater and 2% is surface water. So all of our lakes and flowing water which provide most of the water for our uses make up about .02% of the total water found on Earth.
Water in pure form is colorless, odorless, and tasteless. The air we breathe contains water. Water determines the climate of an area. Water is used for transportation, heating and cooling, farming, power generation, recreation, fire fighting, bathing, cooking, industry and many other uses. We use water in so many ways that we often take it for granted.
Here is a short reader's theater to reinforce the parts of the water cycle (grades 2-5)
CAST: 7 Water Drops, the Sun, a Little Kid
Water Drop 1: Here we are hanging around in this puddle.
Water Drop 2 :Yeah, this is the life!
Water Drop 3: Hey! Look behind that cloud! Guess who??
Drops 1,2,3 : It's the sun! Yay! Evaporation!!!
Sun: Hey guys!! I told you I would see you again soon! What have you been doing?
Water Drop 1: I've been in the ocean! I saw a lot of fish!
Water Drop 2: I've been hanging around on Dr. Pepper and tea glasses. Yummy!
Water Drop 3: I helped water some flowers! They sure smelled pretty!
Sun: It sounds like you were busy! Well, you are up here now, I have done my job, I will see you
Water Drop 1: I wonder who else will show up?
Water Drop 2: It is a little bit cold. I should have brought my jacket!
Water Drop 3: Here are the others! Hi Guys!!
Water Drops 4, 5 ,6, 7 : Hi! How are you?
Water Drop 4: I haven't seen you guys in a long time!!
Water Drop 5: I just got off of a surf board!
Water Drop 6: Really? I just came from a dog's bath. He shook me into the air!
Water Drop 7: It is really getting cold up here! Gather around guys. We need to condense!
All the Water Drops: BRRRRRRRRRRR! I am Freezing! A-CHOOOOO!
Water Drops 4 and 5: It is getting crowded. OOPS!
Water Drop 6: Ah, my favorite part: Precipitation!
Water Drop 7: Yeah, and my favorite kind, snow!
Little Kid: Yay!! It snowed last night!! I'm going to build a snowman!
Water Drop 3: Tee Hee! That tickles!
Water Drop 5: I'm getting smashed here!
Little Kid: Wow! My snowman looks great! I'm going to go eat lunch.
Sun: Well, that was a nice nap, but now I have to do my work. Guess I had better thaw out those
All the Water Drops: We're Melting! We're Melting!
Water Drop 1: Hey guys, we all ended up in the puddle together!
Water Drop 2: And look who is up in the sky!
Water Drop 3: The SUN! Here we go again!!
submitted by SARAH WOOD RALLS ELEMENTARY SCHOOL RALLS, TX sarahw@HUB.ofthe.NET