| Chemistry is an exciting subject for kids of any age, | | | | This next step of the experiment will help you |
| especially if you set up a natural discovery | | | | understand why. You'll need to get the anthocyanin out |
| environment for them to safely explore in. Let's find out | | | | of the cabbage and into a more useful form, as a liquid |
| how to do this in your own home with your own kids. | | | | "indicator". |
| At the university, one of the first things you will learn | | | | Prepare the indicator by coarsely chopping the head |
| about in your chemistry class is the difference | | | | of red cabbage and boiling the pieces for five minutes |
| between physical and chemical changes. | | | | on the stove in a pot full of water. Carefully strain out |
| An example of a physical change happens when you | | | | all the pieces (use cheesecloth if you have it) and the |
| change the shape of an object, like wadding up a | | | | reserved liquid is your indicator (it should be purple). |
| piece of paper. If you light the paper wad on fire, you | | | | When you add this indicator to different substances, |
| now have a chemical change. You are rearranging the | | | | you will see a color range anywhere from hot pink to |
| atoms that used to be the molecules that made up the | | | | tangerine orange to sunshine yellow to emerald green |
| paper into other molecules, such as carbon monoxide, | | | | to ocean blue to velvet purple. Try adding drops of |
| carbon dioxide, ash, and so forth. There's an easy way | | | | indicator to something acidic, such as lemon juice and |
| to tell if you have a chemical change. If something | | | | see how different the color is when you add indicator |
| changes color, gives off light (like the light sticks used | | | | to a base, like baking soda mixed with water. |
| around Halloween), or has heat absorbed (gets cold) | | | | Set out your liquid chemicals in easy-to-pour containers, |
| or produces heat (gets warm). Some quick examples | | | | such as water bottles (be sure to label them, as they |
| of physical changes include tearing cloth, rolling dough, | | | | all look the same!): alcohol, hydrogen peroxide, water, |
| stretching rubber bands, eating a banana, or blowing | | | | vinegar, and dish soap. (Skip the peroxide and alcohol |
| bubbles. | | | | with small kids.) Set out small bowls (or zipper bags if |
| Let's do some experiments that demonstrate the | | | | you're doing this with a crowd) of the powders with |
| chemical changes we've just mentioned. The setup will | | | | "scoopers" made of the tops of your water bottles: |
| look like your kitchen table covered with a plastic | | | | sodium bicarbonate, sodium carbonate, citric acid, |
| tablecloth. On your table will be several bottles of clear | | | | ammonium nitrate, calcium chloride, and alum. The small |
| liquids and white powders along with small measuring | | | | "scoopers" regulate the amounts you need for a |
| spoons and a tray of muffin cups. | | | | muffin-sized reaction. |
| Your mission: To find the reactions that generate the | | | | Have your indicator in a bottle by itself. Old soy sauce |
| most heat (exothermic), absorb the most heat | | | | bottles or other bottles with a built-in regulator that |
| (endothermic), and which are the most impressive in | | | | keeps the pouring to a drip is perfect. You can also |
| their reaction (the ohhhh-ahhhhh factor). NOTE: | | | | use a bowl with a bulb syringe, but cross-contamination |
| Although these chemicals are not harmful to your skin, | | | | is a problem. Or not - depending if you want kids to |
| they can cause your skin to dry out and itch. Wear | | | | see the effects of cross-contamination during their |
| gloves (latex or similar) and eye protection (safety | | | | experiments. (The indicator bowl will continually turn |
| goggles), and if you're not sure about an experiment or | | | | different colors throughout the experiment.) |
| chemical, just don't do it. | | | | The Experiment: Start mixing it up! When I personally |
| Gather these before you start: a muffin cup baking | | | | teach this class, I let them have at all the chemicals at |
| tray, water, vinegar (acetic acid), baking soda (sodium | | | | once (even the indicator), and of course, this leads to a |
| bicarbonate), washing soda (sodium carbonate), rubbing | | | | chaotic mix of everything. After the initial burst of |
| alcohol, hydrogen peroxide, citric acid (grocery store), | | | | enthusiasm, the students will intrinsically start asking |
| aluminum sulfate ("alum" in the spice section of the | | | | better questions. They will want to know why their |
| grocery store or in the pharmacy section of the drug | | | | cold green goo is creeping on the floor with their |
| store), and a clear liquid dish soap such as Ivory. Put all | | | | neighbor's just oozed together a hot pink liquid, |
| these items on your table. | | | | seemingly with the same stuff. Let them figure out a |
| And a head of red cabbage. | | | | system of remembering which chemical goes where |
| Red cabbage? Yes! Red cabbage juice has | | | | and with which to get the reaction they are looking for. |
| anthocyanin, which makes it an excellent indicator for | | | | Periodically hold your hand under the muffin cups to |
| these experiments. Anthocyanin is what gives leaves, | | | | test the temperature. Use the indicator before and |
| stems, fruits, and flowers their colors. Did you know | | | | after you mix up chemicals, and you will be surprised |
| that certain flowers like hydrangeas turn blue in acidic | | | | and dazzled by the results! Enjoy! |
| soil and turn pink when transplanted to a basic soil? | | | | |