ALARA
Alka Seltzer® Poppers
Anti-Gravity Jars
Aspirin Tablets Can Differ
The Burning Candle
Burp Bottle
Carrots: Crispy or Shriveled?
Cartesian Divers
Chemistry of Solutions
Chromatography on Paper
Creaking Plastic Soft Drink Bottles
Curdled Milk
Diet versus Regular Soft Drinks
Dissolving Energy
Entropy, Enthalpy, and Free Energy
Fabric Chromatography
Fat Chance
Frosting Glass
Goldenrod Isn’t Always!
Hold the (Broken) Mayo!
Italian Dressing: Can Oil and Water Mix?
Layering Liquids
The Optical Challenge
Pencil Electrolysis
Penny Sandwiches
Rubber Band Equilibria
A Salty Separation
Sticky Balloons
Stringing an Ice Cube
Sugar versus Salt
Swirling and Churning Milk
The Tarnished Truth
Tissue in a Cup: How Soggy?
What’s in a Potato?
There has been considerable concern lately about the amount of our daily exposure to radiation. The U.S.Nuclear Regulatory Commission has set up guidelines to determine the maximum allowable dose determined by “as low as reasonably achievable” (ALARA) criteria. Are you exposed to more or less radiation than the average American, for whom the annual dose calculated from this activity is 180–200 mrem? You will find out from this activity.
Download 13Kb PDF file.
Alka Seltzer is sometimes taken for acid indigestion. This over-the-counter medication is taken differently than most others since it is added to water before ingesting, rather than being “washed down” with the water.Let’s investigate this addition of Alka Seltzer to water.
Download 12Kb PDF file.
You have probably spilled water from an open jar before. Do you think there is some way to prevent water from spilling from an inverted jar without permanently affixing a lid or other cover? How about employing what you know about the chemistry of water to meet this challenge? Any ideas? Try them and the following activity and see how successful you are.
Download 20Kb PDF file.
The principal ingredient in aspirin is acetylsalicylic acid (many medication tablets also contain a nontoxic, insoluble binder). If you have ever taken aspirin, you may have noticed some stomach discomfort afterward. Manufacturers have developed several techniques to make aspirin easier on your stomach. “Buffered” aspirin includes a buffer to lessen the effect of aspirin’s acidity in the already acidic environment of the stomach. Another advance involves coating the regular aspirin with a substance that prevents the tablet from dissolving until it reaches the basic environment in the small intestine; such aspirin is called enteric. This activity should help you understand how the above modifications to aspirin tablets help to minimize stomach discomfort.
Download 9Kb PDF file.
Can you extinguish a candle without blowing it out, or light it without touching a flame to it? Try the following activity.
Download 10Kb PDF file.
Have you ever burped before? Burping is caused when there is an accumulation of gas in the digestive system. The “burp” occurs when the gas is released through the mouth. You can construct a “burp bottle”to imitate this action. Try this activity to find out how.
Download 19Kb PDF file.
Have you ever had carrots in your refrigerator that became limp? Not too tantalizing. Do you know a way to rejuvenate them? Carrots (and celery), as well as other biological systems, have a membrane covering through which various substances can pass. This activity will show you how to rejuvenate limp carrots and why it happens.
Download 8Kb PDF file.
An object floats in a liquid when it is less dense than the liquid. Do you think that you could make a floating object sink without changing the density of the liquid? Does your answer change when you consider an object that includes a pocket of trapped air? Try the following activity and see what you find.
Download 15Kb PDF file.
Do you know how to make a solution? Can you determine the concentration of the solution that you made? How does your solution behave? Try the following activity and find out.
Download 8Kb PDF file.
We like to make colors an important part of our lives. That’s why manufacturers make products in a variety of colors. Have you ever wondered how these colors are created? We see a myriad of colors all around us, and many of them result from a mixing or blending of other colors.Colored markers are something we commonly use. A single color of marker may contain many different pigments. You can probably make some guesses as to what colors of pigments are contained in marker colors such as green, orange, and purple. How about black and brown? In this activity you will see for yourself. You may be surprised by your colorful results.
Download 12Kb PDF file.
Creaking Plastic Soft Drink Bottles
Have you ever noticed the sounds of cracking and creaking when you throw an empty, capped plastic soft drink bottle in the recycle bin on a very cold day? What happens to a helium-filled balloon that sits in your car for several hours on a very cool day or on a very hot day? Try this activity to see how these occurrences are related. You may need to use your text for the mathematical expression of Charles’ law.
Download 11Kb PDF file.
One material in this activity is milk. Milk contains casein, a protein. When milk sours, the curds that form are coagulated casein. Another material in this activity is rennin (sold as Junket), an enzyme.Obtained from the stomach lining of calves, rennin is used to make ice cream and cheese. A third material is vinegar, which contains acetic acid, a weak acid. What happens when either rennin or vinegar is added to milk? Will changing the temperature affect the functioning of rennin? Try this activity and find out.
Download 11Kb PDF file.
Diet versus Regular Soft Drinks
Cans of soft drinks are so common that many people have done much of this exploration without realizing it. You, too, have probably cooled soft drink cans in ice water for a picnic. Here is your opportunity to see if you can make some generalizations about their behavior in water.
Download 11Kb PDF file.
Household substances are every bit as much “chemicals” as those used in the laboratory. Thus, conclusions based upon experiments utilizing these substances will be equally valid. You are to investigate temperature changes that occur when various household substances dissolve in water.
Download 10Kb PDF file.
Entropy, Enthalpy, and Free Energy
The equation relating these factors is: ?G = ?H–T?S, where G is free energy, H is enthalpy, S is entropy, and T is temperature (in Kelvin). Although temperature values will always be positive,entropy, enthalpy, and free energy values can be positive or negative.For a given process, a quantitative value for each factor can be calculated using the known values of the factors for each reactant involved (see Table 1) according to the general equation? X°rx = ? X°(products)–? X°(reactants). See if the following activity helps you better understand what these quantities really mean.
Download 15Kb PDF file.
Have you ever washed a red and white shirt and had the red dye run onto the white? Sometimes this bleeding of colors can have a positive outcome. Try this exploration to create some intentional bleeding and even some chromatography.
Download 7Kb PDF file.
There has been considerable concern lately about the amount of fat in the foods that we eat.Manufacturers are now required to provide fat content information on food packaging. A simple way for you to determine if any fat is present in the foods you eat is shown by the following activity.
Download 12Kb PDF file.
Pure ionic compounds generally exist as crystalline solids. Try this activity and see how one such compound can be used to make frosted glass.
Download 11Kb PDF file.
Some brands of goldenrod paper contain the dye C.I. Direct Yellow 4. This dye is an acid-base indicator and, as such, is yellow in its acid form and red in its base form. Using this dye (or other similar indicators)to classify a solution as acidic, basic, or neutral involves testing the solution on both forms of the indicator.If the acid form color changes, the solution is basic; if the base form color changes, the solution is acidic;and if neither changes, the solution is neutral.
Download 10Kb PDF file.
Although you were probably not aware of it, emulsions are very common around a household, as evidenced by several familiar foods and many cosmetics. Gourmet cooks and connoisseurs of fine sauces have long recognized the egg yolk as the mark of a classy sauce; one that is smooth and rich,with lots of oil or butter “held” into the water-based mixture. The secret of egg yolk is that it contains lecithin, a naturally-occurring emulsifying agent. Even so, the oil-holding capacity of a sauce is limited, and when too much oil is added (such as in mayonnaise), it “breaks” into two layers.Some substances behave similarly to emulsifying agents, but their effect is temporary. For example,solid paprika and dry mustard help stabilize French dressing by collecting on the surfaces of the oil droplets. Honey and sugar syrup are used to thicken some salad dressings; shaking suspends the oil droplets and their coalescing again is retarded by the viscosity of the liquid.
Download 11Kb PDF file.
Italian Dressing: Can Oil andWater Mix?
You’ve probably shaken a bottle of oil-and-vinegar–type Italian salad dressing to mix it, only to have it separate again before you pour it on your salad. Isn’t this annoying? You can investigate this system to understand why it happens as well as to learn something about some other everyday liquids.
Download 13Kb PDF file.
You probably already know that a cork floats in water because it is less dense than water. You can use this principle to make a density column and to determine the relative densities of different objects.
Download 9Kb PDF file.
Have you ever been momentarily blinded by the flash of a camera? How long does the sensation last?While the answer will depend on the source and intensity of the light, it is not uncommon for a spot of light to remain for several seconds after the flash occurs. This is due to a phenomenon called“persistence of vision.” When light enters the retina, cis-retinal is quickly converted to trans-retinal.But it takes much longer for trans-retinal to convert back to cis-retinal.While light can be emitted from various sources either as a continuous flow or as a very rapid series of flashes, our eyes often do not perceive the difference. Why? Because of persistence of vision.Which common light sources do you think are constant light sources? Which ones do you think are flashing light sources? Try this activity and find out.
Download 10Kb PDF file.
Water is often considered to be a rather stable compound; that is, adding energy in the form of heat only causes a change in its state, but the steam that results is still H2O. Nevertheless, you can use household materials to decompose water into its elements!
Download 18Kb PDF file.
From 1864 until 1983, the usual composition of a penny (its actual name is “cent”) was 95% copper and 5% zinc and tin. Because of the increasing costs of copper, pennies are now composed of a zinc interior with a thin copper coating comprising only 2.4% of the penny. This activity allows you to remove the inside of the penny, leaving only the thin copper coating.
Download 9Kb PDF file.
A rubber band is composed of numerous polymer chains. In the relaxed state the atoms have significant freedom of movement or vibration. (See Figure 1a.) When the polymer is stretched its atoms have less freedom of movement and therefore less vibrational energy. (See Figure 1b.) Is there a change in energy when a rubber band stretches or contracts? Try the following activity and find out.
Download 10Kb PDF file.
It can be difficult to separate a solid from a liquid. Sometimes other chemicals can be added to aid in separation. You can imagine how difficult it would be to separate soap and water once they have been mixed. How well can you do it? Try the following activity and see.
Download 23Kb PDF file.
Can you make plastic cups stick to a balloon? Find out how in the following activity.
Download 10Kb PDF file.
Have you ever tried to handle ice cubes when your hands were wet? If so, you’ve probably had the uncomfortable experience of having your hands stick to the ice! How about driving on roads that have been treated with salt after a winter storm? Discover the relationship between these two experiences and this activity.
Download 8Kb PDF file.
Sugar and salt look almost alike. However, we all know that they taste very different. They are different in other ways, too. In this activity you will discover one of these ways.
Download 9Kb PDF file.
Although you might think food color and soap would spread throughout milk as they do in water,they don’t. Milk’s nonpolar fat globules have an effect on the dispersion, as the following activity will show. You might be surprised by your results!
Download 10Kb PDF file.
Although silver utensils are generally quite attractive, over time they become tarnished as they react with sulfur in the air or in certain foods. You may have had the dubious pleasure of polishing silver and learned that the tarnish is very stable and not easily removed. A common method of cleaning silver is to use an expensive cleaner that removes the tarnish (along with some silver) by abrasion.There is another way to restore the luster that uses less expensive materials, takes less effort, and has another benefit. What do you think it might be?
Download 10Kb PDF file.
Have you washed any cups or glasses recently? Have you ever tried to submerge an inverted glass, jar,or cup into water only to have it bob back to the surface without the inside getting wet? What does this have to do with chemistry? You will find out as you investigate several aspects of this phenomenon through this activity.
Download 13Kb PDF file.
Have you ever used a 3% hydrogen peroxide solution to disinfect an open cut? If so, you probably noticed the formation of bubbles. Although hydrogen peroxide decomposes into water and oxygen gas very slowly at room temperature, the rate increases significantly in the presence of the enzyme catalase. Common substances containing catalase include blood, saliva, and potatoes. Does temperature affect the functioning of catalase?
Download 13Kb PDF file.
AWARD-WINNING BOOKS AND PROFESSIONAL DEVELOPMENT FOR EDUCATORS
| Mickey Sarquis | |
| mickey@terrificscience.org | |
| Terrific Science, Cincinnati, Ohio |