Jim and Trudy Adams
Webelos Adventures in Science Requirement: 3g
Precaution: This is a leader demonstration, not intended as an experiment for scouts.
Single replacement reaction of a metal compound.
Small glass container
Large clean iron nail
Copper sulfate crystals (found in Root Kill product at Home Depot)
Dissolve a rounded teaspoon of Root Kill or other product containing copper sulfate in ½ to 1 cup of water. Stir with a plastic spoon to dissolve crystals. FOLLOW THE CAUTIONS ON THE LABEL OF THE PRODUCT. Stand the nail into the glass container of solution and watch the reaction. (To make sure the nail is clean; you may want to rub the surface with a Scotch Brite pad before placing it in the solution.) The nail should be long enough to be able to pull it from the solution without immersing fingers.
Very soon after the nail is placed in the solution, the part submersed in the solution will begin to change from iron to copper. The solution will also begin to change in intensity of color from bright blue to lighter blue as the nail remains submersed. The iron is changing places with the copper creating iron sulfate and copper. As it sits in water and evaporates, crystals will begin to form on the top of the nail. These crystals are iron sulfate.
Webelos Requirement 3-g
Double Replacement Reaction: Vinegar & Baking Soda (This experiment is less messy than the “volcano”
1 tall plastic bottle with narrow opening
White distilled vinegar
Pour 1/4 to 1/2 cup distilled vinegar into the plastic bottle. (Clear plastic bottle like a heavy plastic 1 liter water bottle, or 1 quart vinegar bottle available at dollar stores)
Using a funnel, put 2-3 rounded teaspoons of baking soda into the latex balloon.
Carefully stretch the opening of the balloon over the opening of the plastic bottle to seal the bottle. Then lift the balloon so that the baking soda falls into the vinegar in the bottle. Watch the balloon inflate.
What happened? (See chemical reactions pages)
In this chemical reaction, the charged particles of the vinegar and baking soda traded places to produce sodium acetate solution and carbon dioxide gas.
The sodium acetate remains in the bottle as liquid, and the balloon is filled with the carbon dioxide gas.
WEBELOS REQUIREMENT 9: ADVENTURES IN SCIENCE
What can we learn from a burning candle?
- Is there a chemical reaction? The wax is decreasing and we can observe new products being formed. It is a chemical reaction.
- What is burning, the wax or the string? Observe closely. The wax decreases and the string gets longer, so, it the wax that burns. (Note: As the string gets longer, it bends over, touching the flame, and the tip turns red, then it burns.)
- What happens to the flame as the string gets longer? Notice at the base of the string just after you light the candle. The wax begins to melt. It is the liquid wax that is pulled up into the flame, called wicking. As the string gets longer, there is more surface area along the string, exposing more wax to burn, and the flame gets bigger.
- What is in the flame and where is the burning taking place? Take a clear glass or bottle and hold the flat bottom in the flame, just above the string. Hold it steady for about 5 seconds. You will observe a black ring, like a donut, on the bottom of the glass. This is soot, or more accurately, carbon. If the glass did not move, or the flame move, you would have a perfect circle of carbon with nothing in the middle. The carbon is moving up the outside of the flame.
- What else is needed for the wax to burn? Turn the glass upside down over the flame, closing off any air to the flame. The flame dies down and goes out. (Note the “smoke” that floats off from the flame. That is unburned carbon.) There is oxygen in the air that is needed to burn, just as we need it to “burn” our food to survive.
- What are the products made from the burning wax? Take the glass, or bottle, and hold it over the flame, but do not lower it below the string. Water forms on the inside of the glass. The wax is a fuel made up of carbon and hydrogen, just as all other fuels. The hydrogen joins with some of the oxygen and makes water, H2O. The carbon joins with oxygen and makes carbon dioxide, CO2.
- Where is the hottest part of the flame? Look closely and you will see 3 colors in the flame: blue at the very bottom, bright yellow in the middle, and a darker yellow tip. The blue is burning carbon where the oxygen hasn’t yet mixed with it. It is the coolest. (Every element burns with its own color. We see burning methane, or natural gas, and it is hotter than a candle, so we think blue is hotter—not in a candle.) The bright yellow shows the addition of oxygen and that is hotter. The tip is where all of the carbon has combined with all of the needed oxygen to complete the reaction and that is the hottest part of the flame.
- One last question: If you are burning candles in a closed room and both you and the candle need oxygen, who wins in the completion for the oxygen? You may think you are hot, but the candle is much hotter and it takes the needed oxygen and you lose. When the oxygen gets low, the flame will still burn, but it will produce carbon monoxide, CO, which is a deadly poison. You will get sleepy, a very sharp headache, and then go to sleep and not wake up.
The actual reaction is: 2C25H52 + 76 O2 –à 52 H2O + 50 CO2 So, in chemistry terms, for every 2 molecules of wax that burns, 76 molecules of oxygen will be sucked out of the air!
Illustration for How Candle Burns
Ever wondered why candies are different colors? Many candies contain colored dyes. Bags of M&Ms or Skittles contain candies of various colors. The labels tell us the names of the dyes used in the candies. But which dyes are used in which candies? We can answer this by dissolving the dyes out of the candies and separating them using a method called chromatography.
For this experiment you will need:
- M&M or Skittles candies (1 of each color)
• coffee filter paper
• a tall glass
• table salt
• a pencil (a pen or marker is not good for this experiment)
• a ruler
• 6 toothpicks
• aluminum foil
• an empty 2 liter bottle with cap
Cut the coffee filter paper into a 3 inch by 3 inch (8 cm by 8 cm) square. Draw a line with the pencil about ½ inch (1 cm) from one edge of the paper. Make six dots with the pencil equally spaced along the line, leaving about ¼ inch (0.5 cm) between the first and last dots and the edge of the paper. Below the line, use the pencil to label each dot for the different colors of candy that you have. For example, Y for yellow, G for green, BU for blue, BR for brown, etc.
Next we’ll make solutions of the colors in each candy. Take an 8 inch by 4 inch (20 cm by 10 cm) piece of aluminum foil and lay it flat on a table. Place six drops of water spaced evenly along the foil. Place one color of candy on each drop. Wait about a minute for the color to come off the candy and dissolve in the water. Remove and dispose of the candies.
Now we’ll “spot” the colors onto the filter paper. Dampen the tip of one of the toothpicks in one of the colored solutions and lightly touch it to the corresponding labeled dot on your coffee filter paper. Use a light touch, so that the dot of color stays small – less than 1/16 inch (2 mm) is best. Then using a different toothpick for each color, similarly place a different color solution on each of the other five dots.
After all the color spots on the filter paper have dried, go back and repeat the process with the toothpicks to get more color on each spot. Do this three times, waiting for the spots to dry each time.
When the paper is dry, fold it in half so that it stands up on its own, with the fold standing vertically and the dots on the bottom.
Next we will make what is called a developing solution. Make sure your 2-liter bottle or milk jug is rinsed out, and add to it ⅛ teaspoon of salt and three cups of water (or use 1 cm3 of salt and 1 liter of water). Then screw the cap on tightly and shake the contents until all of the salt is dissolved in the water. You have just made a 1% salt solution.
Now pour the salt solution into the tall glass to a depth of about ¼ inch (0.5 cm). The level of the solution should be low enough so that when you put the filter paper in, the dots will initially be above the water level. Hold the filter paper with the dots at the bottom and set it in the glass with the salt solution.
What does the salt solution do? It climbs up the paper! It seems to defy gravity, while in fact it is really moving through the paper by a process called capillary action.
As the solution climbs up the filter paper, what do you begin to see?
The color spots climb up the paper along with the salt solution, and some colors start to separate into different bands. The colors of some candies are made from more than one dye, and the colors that are mixtures separate as the bands move up the paper. The dyes separate because some dyes stick more to the paper while other dyes are more soluble in the salt solution. These differences will lead to the dyes ending up at different heights on the paper.
This process is called chromatography. (The word “chromatography” is derived from two Greek words: “chroma” meaning color and “graphein” to write.) The salt solution is called the mobile phase, and the paper the stationary phase. We use the word “affinity” to refer to the tendency of the dyes to prefer one phase over the other. The dyes that travel the furthest have more affinity for the salt solution (the mobile phase); the dyes that travel the least have more affinity for the paper (the stationary phase).
When the salt solution is about ½ inch (1 cm) from the top edge of the paper, remove the paper from the solution. Lay the paper on a clean, flat surface to dry.
Compare the spots from the different candies, noting similarities and differences. Which candies contained mixtures of dyes? Which ones seem to have just one dye? Can you match any of the colors on the paper with the names of the dyes on the label? Do similar colors from different candies travel up the paper the same distance?
You can do another experiment with a different type of candy. If you used Skittles the first time, repeat the experiment with M&Ms. If you used M&Ms first, try doing the experiment with Skittles. Do you get the same results for the different kinds of candy, or are they different? For example, do green M&Ms give the same results as green Skittles?
You can also use chromatography to separate the colors in products like colored markers, food coloring, and Kool-Aid. Try the experiment again using these products. What similarities and differences do you see?
Bear Requirement 3: Chromatography
Have you ever heard the phrase “oil and water don’t mix”? First we will test that expression, and then look at interesting combinations of several other liquids.
Oil and Water
You will need the following materials:
- ¼ cup (60 ml) water
• ¼ cup (60 ml) vegetable oil
• a small glass
• food coloring
First pour the water into the glass. Add a couple of drops of food coloring and mix. Next add the oil. What do you see? Which layer is on top?
Tightly cover the glass with plastic wrap or your hand (if it’s big enough). While holding the glass over a sink (in case you spill), shake the glass so that the two liquids are thoroughly mixed. Set the glass down and watch what happens. Do oil and water mix?
The word “miscibility” describes how well two substances mix. Oil and water are said to be “immiscible,” because they do not mix. The oil layer is on top of the water because of the difference in density of the two liquids. The density of a substance is the ratio of its mass (weight) to its volume. The oil is less dense than the water and so is on top.
The next experiment examines the miscibility and density of several liquids.
You will need the following materials:
• ¼ cup (60 ml) dark corn syrup or honey
• ¼ cup (60 ml) dishwashing liquid
• ¼ cup (60 ml) water
• ¼ cup (60 ml) vegetable oil
• ¼ cup (60 ml) rubbing alcohol
• a tall 12 ounce (350 ml) glass or clear plastic cup
• two other cups for mixing
• food coloring
Layered Liquids page 2
Take the 12 ounce glass. Being careful not get syrup on the side of the glass; pour the syrup into the middle of the glass. Pour enough syrup in to fill the glass 1/6 of the way.
After you have added the syrup or honey, tip the glass slightly and pour an equal amount of the dishwashing liquid slowly down the side of the glass. Does the dishwashing liquid float on top of the syrup or sink to the bottom?
Next mix a few drops of food coloring with water in one of the mixing cups. Color the rubbing alcohol a different color in another mixing cup.
Be careful to add the next liquids VERY SLOWLY. They are less viscous (i.e., not as thick) and mix more easily than the previous liquids. We don’t want them to mix. Tip the glass slightly, and pouring slowly down the side of the glass, add first the colored water, then the vegetable oil, and finally the colored rubbing alcohol.
On a piece of paper, make a sketch of the glass and its liquids, labeling the position of each liquid in your glass.
Why do the liquids stay separated? Can you think of several ways that the liquids in the glass are different? Try to describe some properties that differ in each of the liquids in the glass.
One property that is different in all of the liquids is color. Another property unique to each liquid is thickness (viscosity).
The property of the liquids that is responsible for the layering effect is density. Can you guess what the relationship is between the density of a liquid and its position in the glass?
Another property that keeps the liquids separate is that some of them are immiscible liquids, in other words they do not mix with each other. As you proved in the first experiment, oil and water are immiscible liquids. On the other hand, water and rubbing alcohol are miscible and will mix with each other. Water and the dishwashing liquid will also mix.
Stir up the liquids in the glass and watch what happens to the layers. Have any of the layers mixed (are they miscible in each other)? Wait a few minutes and look again. Have any of the other liquids separated?
Alternate procedure: Rainbow in a glass.
You will need the following materials:
• four different colors of food coloring (e.g. red, yellow, green, blue)
• five tall glasses or clear plastic cups
• ¾ cup (180 g) of granulated sugar
• a tablespoon for measuring
• 1 cup (240 ml) water
In the first glass, add one tablespoon (15 g) of sugar. In the second glass, add two tablespoons of sugar, three in the third glass, and four in the last glass. Then add three tablespoons (45 ml) of water to each glass, and stir until the sugar is dissolved. If the sugar in any of the glasses will not dissolve, add one more tablespoon (15 ml) of water to all of the glasses, and stir again. When the sugar is completely dissolved, add two or three drops of red food coloring to the first glass, yellow to the second, green to the third, and blue to the last glass.
In the remaining glass we will create our rainbow. Fill the glass about a fourth of the way with the blue sugar solution. Next, carefully add the green solution to the glass. Do this by putting a spoon in the glass, just above the level of the blue solution. Slowly pour the green solution into the spoon, raising the spoon to keep it just above the level of the liquid, until the glass is half full. Add the yellow solution, and then the red one in the same manner. What do you notice about the colored solutions?
The amount of sugar dissolved in a liquid affects its density. The blue solution has the most sugar dissolved in it and is therefore the densest. The other solutions are less dense than the blue solution, so they float on top of it. The densities of the solutions should be very close however, and the solutions are miscible, so you will see that the layers do not form well defined boundaries as in the first experiment. If done carefully enough, the colors should stay relatively separate from each other. What do you think will happen if you stir up the liquids in the glass?
Bear Super Science Requirement 6
Many chemical reactions produce both light and heat. A burning candle is such a reaction. When a candle is lit, its flame both glows and becomes hot. It is much less common for a chemical reaction to produce light without heat. The light from such reactions is called cool light, because it is created without heat. Reactions that produce light without heat are called chemiluminescent reactions. Perhaps the most familiar chemiluminescent reactions are those that occur in living organisms. Fireflies produce light without heat by a chemiluminescent reaction. Chemiluminescent reactions that occur in living organisms are called bioluminescent reactions.
In this activity you will examine a commercial chemiluminescent chemical reaction. The reaction occurs inside a Lightstick. Lightsticks are available at many sporting goods stores, camping supply stores, and hardware stores. Amusement parks and carnivals often have them in the shape of bracelets and necklaces.
|Open the wrapper and remove the Lightstick.|
|Describe the Lightstick. What does it look like? What color is it? How big is it? Is anything inside the Lightstick?|
Immediately before activating the Lightstick, record today’s date and the time:
|Date: ____________________||Time: ____________________|
Follow the directions on the wrapper to activate the Lightstick:
- Bend the Lightstick just enough to break the thin glass tube inside the Lightstick.
- Shake the Lightstick to mix its contents.
|Observe the Lightstick in a darkened room.|
|Describe the appearance of the Lightstick. What is the color of the glow? Does the glow come from the entire Lightstick or only from the liquid inside the Lightstick?|
|Immerse the Lightstick in a glass of ice water for five minutes.|
|Does chilling the Lightstick affect its glow? What happens to the glow?|
|Immerse the Lightstick in a glass of warm water for five minutes. DO NOT USE BOILING WATER OR PLACE THE LIGHTSTICK IN THE OVEN. THE PLASTIC SHELL OF THE LIGHTSTICK CAN MELT.|
|What happens to the glow when the Lightstick is warmed?|
Summarize how temperature affects the glow of the Lightstick.
|Put the glowing Lightstick in the freezer for at least 24 hours.|
|Does the Lightstick continue to glow while it is in the freezer?|
|Remove the Lightstick from the freezer and allow it to warm to room temperature.|
|Does the glow come back when the Lightstick returns to room temperature?|
|Observe your Lightstick periodically during the day.|
|How does the glow change with time? How long does it take for the glow to disappear? Where did you keep the Lightstick? What was the approximate temperature of the Lightstick? What could be done to preserve the glow of the Lightstick?|
In this activity you observed the effect of temperature on the glow of a Lightstick. This effect is a result of the effect of temperature on the rate of the chemical reaction that produces the glow. Like all chemical reactions, the reaction that produces the glow is slower at lower temperatures and faster at higher temperatures. In a Lightstick, the faster the reaction the brighter the glow. When the reaction in a Lightstick occurs at a faster rate, it will use up the reactants inside more quickly than when the reaction occurs more slowly. Can you devise an experiment that would test this statement?
|For additional information, see CHEMICAL DEMONSTRATIONS:
A Handbook for Teachers of Chemistry, Volume 1,
by Bassam Z. Shakhashiri, The University of Wisconsin Press,
2537 Daniels Street, Madison, Wisconsin 53704.
Webelo Adventures in Science: Chemical Reactions
Bear Adventure: Forensics
Online resources for Requirement 2: Fingerprints
Online resources for activities for requirement 3: Chromatography
BEAR FORENSICS: REQUIREMENT 4 (Variations of Activity)
Data Table (KEY)
|Fine crystals||Crystals||Powder||Clumpy powder|
|Uniform crystals||Coarser crystals than salt||Fine||Very fine|
|Feel between fingers||Granular||Granular, seems to break up||Fine grit, almost smooth||Very Smooth, sticks to skin|
|Smell||None||Slight sweet smell||None||none|
|Reaction with water||Dissolves||Dissolves||Dissolves||None|
|Reaction with vinegar||None||None||Fizzes||none|
- Ziplock sandwich or snack baggies, clear plastic tumblers, 8 spoons , magnifying glass
- Salt, Sugar, Baking soda, Cornstarch, vinegar, water
- Observation sheet and pencil for each scout
Place about ¼ cup of each of the above items in a clear plastic cup or plastic ziplock bag. Label each of the bags with a number 1-4. Prepare additional 8 clear plastic cups with water and vinegar, and spoons for stirring. Tell the scouts that the bags contain salt, sugar, baking soda and cornstarch. Allow each scout to examine the white powders without tasting, using the observations outlined in the table above. The last two observations can be done as a group to test the reaction with water and vinegar. Scouts will record their observations in the blank table below, and try to determine the name of each powder by its characteristics as they have observed them.
Alternate Activity: Choose one of the 4 powders to be an unknown, telling scouts the names of only 3 of the substances. Using their observations, can they figure out the fourth substance?
STRESS TO SCOUTS THAT THEY SHOULD NEVER TASTE AN UNKNOWN SUBSTANCE AS IT COULD BE POISONOUS!
BEAR FORENSICS: REQUIREMENT 4
Forensic Data Table
|Feel between fingers|
|Reaction with water|
|Reaction with vinegar|
Figuring Out the Unknown substance by observation
Crystal Powder Granular Smooth
Salt Baking Soda Salt Baking Soda
Sugar Cornstarch Sugar Cornstarch
Reaction with Water Reaction with Vinegar
Dissolves: salt, sugar, baking soda No reaction: salt, sugar, cornstarch
Not dissolved: cornstarch Fizzy reaction: baking soda