fun chemistry experiments
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AHA! Lesson Plan – Crazy Chemistry 1 Crazy Chemistry Lesson Plan Objectives The scientists will: • Observe the separation of colors in ink. • Learn about water molecules, cohesion, and surface tension. • Determine the difference between two types of packing peanuts. • Create a chemical reaction within a test tube that will cause a balloon to inflate. • Create a chemical reaction that will result in lemon suds soap. • Experience how the sense of taste is related to the sense of smell. Materials • Green and black water-soluble pens • Baking soda • Coffee filters • Spoon and/or Funnel • Saucer (or Styrofoam plates) • White vinegar • Paper clips • Balloon • Test tube • Lemon or lemon juice • Test tube rack • Plastic cups • Water • Liquid soap (Ivory or Dawn) • Styrofoam packing peanuts • Paper towels • Cornstarch packing peanuts • Life Savers or other flavored candies Procedures 1) Introduce the topic of Chemical Reactions - a process in which one or more substances are changed into others. 2) Follow Procedures for “Rainbow Effect.” Ask the children to guess (hypothesize) what is going to happen. Set the plates aside and come back to them at end of program. 3) Follow instructions for “Over-Filled Tube.” Ask children to guess how many paper clips it will take to make the water rise. As you surpass their guesses, let them pick a new number. Once the water spills over the edge, explain what happened by defining cohesion and surface tension. (See Over-Filled Tube: What’s Goin’ On?) 4) Follow instructions for “Packing Peanut Puzzle.” Children will observe what happens to each of the packing peanuts. Explain the chemical reaction of the cornstarch dissolving in water. 5) Follow instructions for “Balloon Inflator.” Ask the children what is going to happen. (nothing? balloon blows up a little? balloon blows up a lot? balloon explodes?) 6) Follow the procedures for “Lemon Suds.” This time the children will see a chemical reaction between the baking soda and citric acid (lemon juice). At the end of this experiment, have the children clean their stations with the lemon-scented cleaner they have created. 7) Return to the coffee filters and saucers. There should be trails of blue, yellow, and red from the black mark, and trails of blue and yellow from the green mark. The ink is dissolving; the AHA! Lesson Plan – Crazy Chemistry 2 water is carrying the pigments along at different rates, depending on the size of the pigment molecules and on how strongly the pigment is attracted to the paper. This technique of separating pigments/colors is called chromatography. 8) Talk about the tongue and its four types of receptors – sour, sweet, salty, bitter. Explain how taste is related to sense of smell. Talk about how when you are sick with a cold and stuffed up nose, sometimes food does not taste right. Follow the steps for “Your Sense of Taste.” Have the children guess what flavor candy they were given. It’s harder than they think! Conclusion Which experiment did you enjoy the most today? What did you like about it? Try making soap suds at home and help clean up the kitchen with your lemony creation! AHA! Lesson Plan – Crazy Chemistry 3 Rainbow Effect Materials • Green water-soluble pen/marker • Black water-soluble pen/marker • Coffee filter • Saucer • Paper Clip Procedures 1) Fold the coffee filter in half. 2) Fold it in half again. 3) Make a dark green mark about one inch from the rounded edge of the folded filter. 4) Make a second mark with the black marker about one inch from the rounded edge. The two marks are not to touch each other, but need to be on the same side. 5) Secure the edge of the filter with the paper clip so that a cone is formed. 6) Fill the saucer with water. 7) Place the rounded edge of the cone in the water. 8) Allow the paper to stand undisturbed for one hour. Results It takes about one hour for the colors to separate. A trail of blue, yellow, and red is seen from the black mark, and the green mark produces a trail of blue and yellow. Why? Black and green are combinations of other colors. As the water rises in the paper, the ink dissolves in it. Some of the colors rise to different heights depending on the solubility of the chemicals producing the color. The more soluble chemicals move with the water to the top of the paper. Source VanCleave, Janice Pratt. Chemistry for every kid: 101 easy experiments that really work. New York: Wiley, 1989, pp 154-155. AHA! Lesson Plan – Crazy Chemistry 4 Over-Filled Tube Equipment • Paper clips • Super Tube™ and rack • Water Try This! 1) Set the Super Tube in the support rack. Completely fill the tube with water. The water should rise slightly above the rim. If needed, add more water. Looks pretty full, right? 2) How many paper clips do you think you could add to the tube without making the water overflow? 3) Now, carefully add paper clips to the water, one at a time, until the water spills over the tube’s edge. How many did you add? If you added more than you thought you could, congratulations! What’s Goin’ On? Water molecules like to hang onto each other, sort of like magnets. This force is called cohesion. As more paper clips are added, the molecules get stretched until they can’t hold on anymore. They break apart, and the water spills over the tube’s edge. The mound of water that appears over the top of the tube is caused by surface tension. This is the name given to the cohesion of water molecules on the surface of water. (“Linked” water molecules also help bugs, such as water striders, walk across the water in ponds without sinking to the bottom. The pressure their weight puts on the water is not strong enough to break the surface tension, so they stay afloat.) Eventually, the mound of water is weakened by gravity and air pressure, and the surface tension breaks. Water runs down the outside of the tube. You may want to try this experiment again, but this time add a drop of liquid soap to the test tube. (Soap molecules can slip in between water molecules.) How do you think this well affect your results? Source Super-Tube Science ™: Amazing Air & Water. Greensboro, NC: Wild Goose Company, 2005, pp. 11-12. AHA! Lesson Plan – Crazy Chemistry 5 Packing Peanut Puzzle Equipment • 2 Super Tubes™ with rack • Foam packing peanuts (both kinds) • Magnifying lens • Water Try This! Part 1 1) Take a closer look at each type of “peanut.” Do they look different? Gently squeeze both peanuts. Do they feel different from each other? Break them apart. How would you describe the texture? 2) Place two Super Tubes in the support rack. Pour water into each tube just up to the 40 mL mark. 3) Drop one foam packing “peanut” into the first tube and place one of the other type of packing “peanuts” into the second tube. 4) Check out what happens to the “foam peanut” in each tube. Try This! Part 2 1) Dissolve a couple of the cornstarch peanuts in water. 2) Now spread the mixture on paper. Can you use it to hold pieces of paper together? Who needs school glue! Explanation The packing “peanuts” are made out of different materials. The one that dissolved is made from cornstarch, a material found in corn that is sometimes used to thicken foods. Sine it dissolves in plain water, it is not harmful for the environment when thrown away. This means that if you trash the packaging for the birthday gift that was sent to you, the cornstarch packing “peanuts” will dissolve in the landfill when the soil is wet. The other type of “peanut” is made from polystyrene, which is a kind of plastic foam. Those peanuts don’t dissolve in water – so it’s better to reuse or recycle them and keep them out of the trash! Source Super-Tube Science ™: Discover Chemistry. Greensboro, NC: Wild Goose Company, 2005, pp. 20-21. AHA! Lesson Plan – Crazy Chemistry 6 Balloon Inflator Equipment • Balloon • Super Tubes™ and rack • Baking soda – or sodium bicarbonate • Spoon • White vinegar Try This! 1) Place a Super Tube in the support rack. Add vinegar up to the 10 mL mark. 2) Put 1 tsp. (13 mL) of baking soda (sodium bicarbonate) into the balloon. (Use a small funnel to make this step a lot easier!) 3) Twist the balloon so the baking soda is trapped inside at the bottom of the balloon. Then stretch the mouth of the balloon over the opening of the tube. Be sure to keep the balloon twisted shut! 4) Hold the balloon straight up over the top of the tube. Carefully untwist the balloon so that the baking soda will fall into the vinegar. 5) Stand back and watch what happens! What’s Goin’ On? The setup is a closed system, which means everything is trapped in the space inside the Super Tube and the balloon. When baking soda (sodium bicarbonate) and vinegar (acetic acid) are mixed together, a gas called carbon dioxide is produced. In fact, they can make tons of carbon dioxide when mixed together. Those gas molecules are very active; they’re busy zooming around and pushing on things. One of the things the molecules push on is the balloon, so it inflates! Source Super-Tube Science ™: Discover Chemistry. Greensboro, NC: Wild Goose Company, 2005, pp. 29-30.