Fizzy science

Five fun experiments using vinegar and baking soda.

Integrating Science in Your Classroom

This month, let's explore chemical changes using ordinary household materials. Vinegar contains an acid (acetic acid) and baking soda is a base. When these two materials are in contact with each other, say, in a drinking glass, they form a salt called sodium acetate and a weak acid called carbonic acid (H2CO3).

Carbonic acid is unstable (it tends to change) and falls apart in water. Carbon dioxide, a gas,, causes the vinegar in the glass to foam. Since vinegar's reaction with baking soda is a chemical change, it is not reversible (Example of a reversible change: Water can change into ice and then back into water again).

Here are five fun and safe experiments involving chemical changes that can be made with vinegar and baking soda.

Simple Vinegar and Baking Soda Experiment (Grades K-3)

Materials: Cup or drinking glass, teaspoon, vinegar, baking soda.

Procedure: Half-fill a cup or drinking glass with vinegar. Add a teaspoon of baking soda to the vinegar. The liquid will foam over the top of the cup. Add different amounts of baking soda to the vinegar. How many spoonsful of baking soda create the most foam? Try this experiment with warm vinegar. Does warm vinegar give more foam than room-- temperature vinegar does? Add a drop of dish detergent to the vinegar. Does this foam even more?

Old-Fashioned Fire Extinguisher (Grades 4-8)

Old fire extinguishers used simple chemistry: A bulb container was filled with two reacting agents that were separated until they were put into use. In the event of a fire, the user would shake the bulb vigorously to combine the agents. The mixture would then fizz and create carbon dioxide foam that would escape in a spray from a nozzle attached to the bulb container. The carbon dioxide spray replaced the oxygen that a fire needs in order to continue burning and, in that way, extinguished the fire.

You can create a similar extinguisher using ordinary household materials.

Materials: A 500 ml (16.9 ounces) plastic bottle with screw top, tea bag, fork, teaspoon or 5 ml spoon, scissors, paper clip, drill, vinegar, baking soda.

Procedure: Drill a small hole in the center of the bottle's screw top. Using the prong of a fork, carefully pry the staple off a tea bag so you can unfold the bag. Don't use a staple remover - you might tear the bag.

Cut the label from the string, but don't remove the string from the tea bag. Cut off the end of the tea bag opposite the string and empty out the tea. Replace the tea with two teaspoons (10 ml) of baking soda. Fold the bag in half and paper-clip it together.

Fill the plastic bottle to the halfway mark with vinegar. Tie the end of the tea bag string to the neck of the bottle, then carefully push the tea bag into the bottle so that it hangs about 1.5 inches (7.5 cm) from the vinegar.

Screw the cap on the bottle. When you're ready to test your extinguisher, place your finger over the hole and shake the bottle so that the vinegar saturates the tea bag. The tea bag should open and spill its baking soda into the vinegar. Turn the bottle on its side with the cap facing away from you and remove your finger. White foam should spray from the hole in the bottle cap.

Try different amounts of vinegar and baking soda to produce the best pressure. Also, try different hole sizes in the cap. Begin with small holes and then create larger holes.

Self-Inflating Balloon (Grades K-5)

Materials: Large, round party balloon, two-liter plastic soda bottle, vinegar, funnel, waxed paper, baking soda, spoon.

Procedure: Cut a 10-inch by 6-inch piece of waxed paper. Spoon a half-inch-thick strip of baking soda powder down the center of the long (10-inch) side of the paper. Roll the waxed paper to make a 10-inch long, half-inch thick cylinder. Next, fold over the two ends. Push the cylinder into a two-liter plastic soda bottle. Pour 1-2 cups of vinegar into the bottle through a funnel.

Quickly stretch the mouth of the large, round balloon over the open end of the bottle. Pick up the bottle and shake it vigorously for 10 to 20 seconds. The balloon will rapidly swell because the reaction of vinegar and baking soda produces carbon dioxide gas. The gas pressure inside the bottle quickly increases, causing the balloon to inflate.

Extension: Try the experiment again, but this time, put the baking soda in a folded-- up piece of toilet tissue. Does that work better? Try inflating the balloon with a mixture of cold vinegar and baking soda. Then try a mixture of hot vinegar and baking soda. Which inflates the balloon the best?

"Plop-plop, Fizz-fizz..."

(Grades 3-6)

Long ago, when I was in junior high school, my science teacher did the following experiment: She broke an Alka-- Seltzer- tablet into four pieces and placed them into an empty film canister. Then, she poured approximately one ounce of water into the container, quickly placed the film canister's cap on tightly and stepped back. Within a few seconds, the cap blew off the canister and hit the ceiling of the classroom. "Wow!" I thought. "What a powerful aspirin!" Try duplicating this experiment in your own classroom.

SAFETY NOTE: To do the above experiment everyone must wear safety goggles and should get far away from the loaded film canister.

Speeding Up a Chemical Reaction (Grades K-5)

Here's a simpler and safer way to speed up chemical reaction using antacid tablets. Materials: Three Alka-Seltzer tablets (or other antacid tablets), baking soda and a homemade acid-base fizzy mixture (baking soda + citric acid), water, three clear plastic cocktail cups (or equivalent).

Procedure: Prepare three glasses of water: Add cold water and an ice cube to glass #1, add lukewarm water to glass #2 and add hot water to glass #3. Quickly add an antacid tablet to each of the glasses. What do you see happening in each glass?

What occurred? Each glass of water gave off bubbles after an antacid tablet was added. An antacid tablet is supposed to react with itself when it dissolves in water. The active fizzing ingredients in the tablets are citric acid (an acid known as sour salt) and sodium bicarbonate (a base known as baking soda). The baking soda contains carbon dioxide, a gas which is released when the baking soda is neutralized with acid.

Hot water produces bubbles the fastest, causing the antacid tablet to noisily, almost explosively, dissolve in just a few seconds. Why? Because it (1) quickly dissolves the tablet and (2) speeds up the reaction of the acid and base in the tablet.

These experiments provide a simple, graphic introduction to chemical reactions, which occur around us every day - even between common substances like the ones used here. Join me next month for more classic experiments using ordinary household items.

John Cowens teaches science at Fleming Middle School, Grants Pass, OR, and is a Teaching Editor of Teaching K-8. E-mail: snewoc@yahoo.com

Copyright Early Years, Inc. Jan 2002
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