Teaching Children About Acids and Bases
July 31, 2018
Have you ever tried to teach kids about the fundamentals of acids and bases, only to be met with groans and other bored reactions? We understand that that’s no fun. Maybe you’re excited about the concept and want to make it interesting for the kids, but are struggling to find a way to make such a potentially dry topic come alive.
The key to doing this is by showing your students just how far from dry this topic actually is. The reason they may be uninterested is because they might think of it as an obscure chemical concept that has no effect on them whatsoever. But what if you could prove that the opposite is the same? By showing your kids all the ways in which this concept is active in their everyday lives, you can help spark interest, exploration and excitement.
To help you do just this, we’ve pulled together a few quick tips and ideas for teaching kids about acids and bases. We’ll go over the basic concepts in simple language that’s appropriate for children as well as look at some fun experiments you can do to play with these ideas.
What Are Acids?
You may have heard of the term acid before, and you have likely heard something referred to as acidic. And while you may have a general idea of what these terms mean, it’s helpful to understand what these terms mean on a scientific level.
Think of beverages like lemonade or orange juice. Think of the delicious tangy taste you get when you sip either of these beverages. That tang is the direct result of these beverages’ acidic nature. The reason that these beverages and many other substances are naturally acidic is because they contain lots of hydrogen ions. An ion is a special type of atom or molecule that has an electric charge. A hydrogen ion, then, is one that has a tiny electrical charge.
Every substance in the universe is made up of hundreds and thousands of tiny atoms, molecules and ions. When a large number of those are hydrogen ions, the substance is acidic. In food, that means it will have a sour or tangy taste. Lots of things other than food can be acidic as well, though.
What Are Bases?
Base is a term we rarely use in everyday life, at least in this context, and that means it might be a slightly less familiar concept. One everyday example of a base substance is baking soda, commonly used to bake cakes, cookies and other sweet treats. If you try to taste this, you’ll see that it’s very bitter. If you rub it between your fingers, you’ll find it has a strange, soapy feeling. This is all because baking soda has a basic nature.
Basic substances contain lots of hydroxide ions. These are a different type of molecule with a small electrical charge. In foods, this means they will taste more bitter. Plenty of things other than food can be basic, however.
What Is the pH Scale?
The pH scale is another concept you may have heard of without much reference for what it is and how it works. But while the name might sound intimidating, the idea is actually pretty simple.
Think of the pH scale as a ruler that we can use to measure how acidic or base something is. There are 14 different possible point values on the scale, and each one represents a possible level of acidity or baseness. A substance is acidic if it has a pH level of 0 through 7, where 0 is the most acidic. A substance is basic, then, if it has a pH level of 7 through 14, where 14 is the most basic. If a substance has a pH of exactly 7, it’s neutral. This means it has equal amounts of hydrogen and hydroxide ions. Pure water is a neutral substance.
If an item measures at a 3 on the pH scale, then, we can see that this substance would be quite acidic, although not as acidic as other substances. Something that measures an 8 would be slightly basic.
What Is an Indicator?
We mentioned earlier that certain foods are more basic or acidic, and you can tell this by tasting them. Lemonade, for example, is clearly sour and tangy, helping us realize that it must be acidic. Baking soda, on the other hand, is bitter and we can easily recognize that it is more basic.
What about things that aren’t food, though? After all, plenty of different substances throughout nature have either an acidic or basic nature. Logically, we can’t go around tasting all of these different things to tell where they fall on the pH scale. So how do we test them?
We use an indicator to compare acids and bases. An indicator is a special type of substance that tells us whether the item in question is more acidic or basic. Believe it or not, there are a few naturally occurring indicators that we can use to determine the pH of a substance. Litmus and turmeric are great examples of natural indicators.
Out of all of those natural indicators, the one we use most frequently in a classroom setting is litmus. This is a type of material that comes from lichens, which are plants that grow along walls, trees or rocks. Litmus has a naturally purple color, but it can change its color. When it comes into contact with an acidic substance, it turns red. When a basic solution touches it, it will turn blue. Because of this unique property, litmus is a handy indicator. When we use it today, we most often use it in the form of small sheets known as litmus papers.
Where Do We Find Acids and Bases in Nature?
While acids and bases might sound like obscure chemistry terms that we would never encounter except in a lab, this isn’t true. Acids and bases are all around us in daily life. Lots of plants have leaves, stems, roots and flowers that are either acidic or basic. Plenty of fruits are acidic or basic, and even ordinary things like soda and milk fall somewhere on the pH scale.
Even inside our bodies, there are lots of acidic and basic substances. There are acids in our stomach that help with digestion, and our muscles produce acid when we exercise. Our pancreas is basic and helps in the digestion process as well. All these different acids and bases work together in our bodies to keep things running smoothly.
Acids vs. Bases Experiments for Kids
Because acids and bases pop up all over the place in nature, as well as in plenty of human-made settings, what are some fun and interesting ways to play with these ideas? As it turns out, there are plenty. Try a few of these experiments to get everyone interested in the ideas of acids and bases.
1. The Red Cabbage pH Test
Red cabbage is a great natural indicator and is perfect for use in classroom experiments. To get this test started, slice some red cabbage, put it in a pot with some water and let it simmer for 30 minutes or so. Strain the liquid out, set it aside and then you’re all ready to get started.
Grab a couple of small rectangles of white paper. Index cards are a great choice, but you can also cut out regular pieces of scrap paper. Soak them in the red cabbage water and let them dry.
Take a white paper plate or a thick sheet or white paper and drip a few drops of your cabbage water onto this surface. Take an acid, such as lemon juice, and a base, such as baking soda, and add a small amount into different sections of your cabbage water samples. The water will change color as a result and will look like magic in the process. With a solid explanation of bases and acids under their belts, kids will enjoy watching the colors change in response to the different liquids.
Another way to use this cabbage water is to pour a few inches of it in two separate glasses. Add water to these glasses as well, until they’re about two-thirds of the way full. Finally, add a base to one glass and an acid to the other and watch the entire glassful of liquid change colors.
Once your homemade litmus papers are dry, cut them into smaller strips. Now the kids can perform their very own litmus tests with all kinds of different materials and substances. Pull different things out of the fridge and let the kids use the papers to test them. Some good things to try include pickle brine, apple juice and soda. Before you dip the papers into the substances, ask the kids to guess whether an item will be acidic or basic, and make a game out of it. Show them how to record their predictions, along with whether or not they were correct.
Of course, if red cabbage is unavailable or if you’d rather not go through the process of creating your own litmus papers, you can simply buy prepared litmus papers in many different stores. These pre-made papers will work in exactly the same way and can be used to perform the same tests.
2. The Copper Coin Experiment
Do you have any tarnished copper coins lying around? If so, they can make a great experiment.
For this to work, you’ll want to take a few different cups and pour a small amount of a liquid solution into each cup. Try a few different solutions that you know to be acidic, and a few others that you know to be basic. Then, all you have to do is drop the copper coins into the solution. You can lay them flat in the bottom of the cup, although the results will be more striking if you can stand the coin on end so that only half gets soaked in the liquid.
The acids will dissolve the tarnish that has collected on the copper coins, restoring them to their original shiny selves.
3. The Raw Egg Experiment
Another great experiment to try involves a raw egg. While this one is fun to do and fun to watch, the kids might also enjoy making predictions with this one and trying to guess what will happen.
For this experiment, keep things simple. Take a raw egg and submerge it in a bath of vinegar. Ask the kids what they think will happen. As you might be able to guess, the highly acidic vinegar breaks down the shell and effectively turns it into an acid-cooked soft-boiled egg. It will even bounce if you drop it carefully.
4. The Jet-Powered Boat
This experiment works best in a bathtub, a large sink or even a blow-up pool in the backyard. To get started, take a regular plastic water bottle and drill a hole straight through the cap. Thread a thin straw through this hole and use some modeling clay to help you hold this straw in place and plug the gaps around it. When you eventually submerge the bottle in your pool, this clay will also help weigh that end of the bottle down and keep it underwater.
Fill the water bottle with a solution of half water and half vinegar. Be careful not to fill the bottle all the way, and instead leave a space of empty air near the top. When your bath or pool is filled, set the experiment in motion by adding about half a teaspoon of baking soda to the bottle. Immediately cap the bottle and cover the end of the straw with your finger before placing the bottle in the pool and letting go.
The acid of the vinegar and base of the baking soda will violently react with one another, fizzing and creating “jet fuel” that will shoot out the end of the straw and propel the boat across the pool.
Keep Your Kids Interested in Science
Did your kids enjoy learning about these fascinating ideas? Did their eyes light up as they watched these concepts come to life in front of them in the form of exciting experiments? If so, it’s important to nurture and encourage these interests.
If any of your science adventures have sparked a kid’s interest in science, consider enrolling them in a science summer camp or an after-school science club. Both of these are great ways to allow kids to continue exploring these interests and learning new and exciting concepts in the company of their peers.
If you live in the Pennsylvania, New Jersey, Delaware or Maryland area, our Science Explorer camps are week-long events in the summer that are held at schools, museums, libraries and other educational settings near you. If summer has already ended, however, there’s no need to worry. We also offer after-school programs for kids in grade one through five, although this will vary from school to school.
Visit our information pages to learn more about our summer programs and after-school clubs. If you have any questions, don’t hesitate to contact us. We’ll help you find a program that will be the best fit for your young science explorer!