Chemistry experiments for kids are a great way for parents to spend quality time with their children, have fun, and learn something all at the same time! Remember than running and rationalizing experiments is one of they cornerstones of learning science.

Here are a couple of fun chemistry experiments that your kids are sure to love.

Chemical Reaction Experiments for Kids: Green Pennies and Copper-Plated Nails

This awesome experiment is really three chemistry experiments for kids in one! First, in Part 1, an acid-base reaction gives dull pennies their original shine back. Then, in Part 2, we use redox chemistry to turn some of those pennies green. Finally, in Part 3, we coat ordinary steel nails in copper.

What you’ll need:

About 20 dull pennies

A shallow bowl (glass or plastic only)

¼ cup white vinegar

1 teaspoon salt

A couple of clean steel nails

Water

Paper towels

Part 1: Making Dull Pennies Look Shiny and New

Combine the vinegar and salt in the bowl and stir to dissolve the salt. Start by dipping a penny halfway into the vinegar solution and holding it there for 20 seconds. Make a note of what you see. Dump the remaining pennies into the bowl and leave them there for 5 minutes. Your pennies should be bright and shiny again! Reserve the solution for Part 3.

What’s going on?

Over time, shiny copper pennies get dull because the metal is gradually oxidized when in contact with air. The chemical reaction for this process is 2 Cu (s) + O 2 (g) –> 2 CuO (s). Copper (II) oxide (CuO) or cupric oxide, the product of this reaction, is dull and greenish. So, a layer of this substance on the surface of the penny makes it look dark brown and dull.

Cupric oxide is also soluble in many acids, including the acetic acid in household vinegar. When you place the dull pennies in the vinegar solution, the acetic acid dissolves the cupric oxide on the surface of the pennies, revealing the shiny pure copper metal underneath.

It’s an acid-base reaction that results in invisible copper ions (Cu2+) being left in the vinegar solution: CuO (s) + 2 CH 3 COOH (aq) –> Cu(CH 3 COO) 2 (aq) + H 2 O (l). This will be important in Part 3, so don’t throw this solution away!

Part 2: Green Verdigris Pennies

Remove the pennies from the vinegar solution. (Keep it for Part 3.) Place half on a paper towel to dry, and rinse the other half thoroughly in clean water before placing them on a separate paper towel. Label the paper towels so you know which is which. Wait about an hour and note the difference between the two sets of pennies. The unrinsed pennies should have turned a blue-green color!

What’s going on?

The turquoise-colored coating on the unrinsed pennies is a patina called verdigris. You might recognize it as being similar to the color of the Statue of Liberty—that’s verdigris, too! While verdigris can be several different compounds, in this fun chemistry experiment, it is copper (II) acetate, or cupric acetate.

It’s a two-step process. First, the copper metal is oxidized to cupric oxide, exactly the same way it does naturally over time. However, in this experiment, we have sped up the oxidation reaction using salt (NaCl) dissolved in the vinegar. Sodium chloride is an electrolyte, and since oxidation-reduction reactions rely on the movement of electrons, an electrolyte acts as a catalyst by increasing the conductivity of the solution.

In the second step, the acetic acid left on the unrinsed pennies reacts with the cupric oxide to form blue-green cupric acetate: CuO (s) + 2CH 3 COOH (aq) –> Cu(CH 3 COO) 2 (s) + H 2 O (l)

Notice that this is the same reaction that dissolved the cupric oxide in Part 1. The difference is that we’ve taken it out of the aqueous environment. Because of this, the solid cupric acetate remains on the penny as the water evaporates.

Part 3: Copper-Plated Nails

Place one nail in the solution from Part 1 so that it is half covered, and completely submerge another nail. Note any changes you see. Leave the nails that way for about 10 minutes. If the color hasn’t changed, come back again in an hour. The parts of the nails in contact with the solution should now be coated in copper!

What’s going on?

Steel is an alloy whose main component metal is iron. When you dip the nails in the penny-cleaning solution, the acid in the vinegar dissolves some of the iron and iron oxides on the surface, leaving it with a negative charge.

Remember those invisible Cu2+ ions that were left behind in solution? Those positive ions are attracted to the negative charge on the surface of the nail. As a result, the copper ions are reduced (i.e. gain electrons) to pure copper metal, which is deposited all over the nail.

This is definitely one of the coolest chemistry experiments to do at home, and you probably have everything you need already!

More Chemistry for Kids: Coffee Filter Chromatography

Running chromatography in a coffee filter

This is one of the easiest chemistry experiments with household items, which makes it suitable for even younger kids. It’s an at-home version of something chemists do in the lab every day: chromatography. Here, you will take a dye from markers and separate it into its component pigments.

( As a fun continuation of this experiment, why not use water to pull the dye off of colored candies, like M&Ms and Skittles? Do you think red M&Ms contain the same pigments as red Skittles? How can you find out? )

What you’ll need:

Coffee filter

Ruler

Scissors

Pencil

Non-toxic markers (or other source of dye)

Water

Table salt

A tall glass

What to do:

Cut the coffee filter into a square, approximately 3 inches by 3 inches, and use a pencil to lightly mark a line straight across the filter, about a half inch from the edge. Next, use the pencil to make dots for each dye color you are going to test, equally spaced along the pencil line, and label each dot with the name of the color. Now, use each marker to make a small dot on the pencil dot by its corresponding label. Ensure that each colored dot is approximately the same size. Prepare a 1% salt solution by dissolving 1/8 tsp table salt in 3 cups of water. Once the salt is dissolved, pour a small amount of solution into the tall glass. The water level should be approximately ¼ inch high. It is very important that it be lower than the marker dots on your coffee filter. Crease the filter square vertically down the middle so that it can stand upright. Then, gently set it in the glass so that the edge below the marker dots is in the salt solution. Water will start to move up the coffee filter. When the water has almost reached the top of the filter square, remove it from the solution and let it dry. The pigments in the markers should have been carried up the filter, some farther than others. What do you see?

What’s Going On?

This chemistry experiment with household items is a simplified form of chromatography, a technique that real scientists use to separate components of a solution every day.

There are two phenomena at work here. First, capillary action is what causes the liquid to defy gravity and move up the coffee filter. This happens in small tubes (like the porous fibers of the coffee filter) when the intermolecular forces between the liquid and the tube are stronger than the force of gravity pulling on the mass of liquid in the tube.

But the second part is what makes chromatography so useful. Some of your marker colors will have moved higher up the coffee filter than others. It’s likely that a few of them even separated into multiple dyes (e.g. a blue spot and a yellow spot came from your green marker). Chromatography uses the different physical and chemical properties of different molecules to separate them in this way.

Sometimes, a dye will move faster up the coffee filter (the “stationary phase”) simply because it is a smaller molecule and weighs less. Usually, though, molecules are separated by their affinity for the stationary phase or the “mobile phase” (the salt solution in our case).

More polar molecules will have a stronger affinity for the positive and negative ions in the salt water, for example, and will be carried up the filter more easily. Nonpolar molecules, on the other hand, will not have any attraction to these charges, and will not get swept away by the solution so quickly.

Your Own All-Natural pH Indicator

Making a pH indicator at home. Credit to ScienceKiddo

Tons of household liquids “behave” the way they do because they are acidic, neutral, or basic. You could check the pH of these liquids with test strips or an indicator solution you buy at a pool supply store or the pet shop. But did you know you can do this with an ordinary vegetable?

The gorgeous colors in this simple experiment make it chemistry for kids at its best!

What you’ll need:

Half a red cabbage

2-3 cups boiling water

Strainer

Various household liquids for testing (e.g. plain water, lemon juice, baking soda solution)

One clear glass for each liquid

Additional water for diluting

What to do:

Prepare the pH indicator from the cabbage. To do this, chop the cabbage into small pieces, cover in a saucepan with boiling water, and let cool. Strain to separate the liquid, which should be dark purple. This is your indicator solution. Dilute a small amount of your household substances in water in separate glasses. Make sure to label them so you know what’s what. It’s a good idea to have one glass of plain water to act as a control. Predict what color each liquid will turn when you add the pH indicator, and then see if you’re right by pouring a small amount into each glass. Neutral liquids should be purple, like the indicator itself. Acidic liquids should turn hot pink, and basic liquids should turn blue!

What’s going on?

Acidity, for the purposes of pH, is a measure of hydrogen ions (H+) in a solution. A pH of 7 is considered neutral. If a liquid is acidic, its pH will be between 0 and 7, and if a liquid is basic or alkaline, its pH will be between 7 and 14.

A pH indicator works by reacting with acidic (H+) and basic (OH–) ions in a solution; the product of that reaction is a different color than it was originally, thus indicating whether the solution was basic or acidic.

In red cabbage, the plant pigment anthocyanin has a molecular structure that allows it to act as both a base (reacting with acids) and an acid (reacting with bases). It therefore has three different forms, each with a different color, depending on the number of acidic hydrogens it contains (fully protonated in an acidic environment, partially protonated in a neutral environment, and fully deprotonated in an alkaline environment).

Final Thoughts on Chemistry for Kids

These fun chemistry experiments with household items are simple, safe and visually interesting for kids. But to make sure they get the most out of it, don’t forget to ask them questions (and do your best to answer theirs). What do they see? Why might that be happening? What would happen if you changed the conditions slightly?

You’ll have a budding scientist before you know it!

Also, make sure to check some of the more general science experiments that you can do at home that we have also published recently.