When the weather keeps you from going outside, do some fun indoor chemistry projects instead! Try these easy science projects below to learn the chemistry behind some everyday things that are fun and enjoyable to have around.

Indoor Chemistry Project: Bath Salts and Soft Water

Not just the scents are at work here to make your bath more relaxing. Try this project and learn what salts can do.

What You Need:

  • Plastic mixing bowl
  • 1 cup Epsom salt
  • 1 cup sea salt
  • 1/2 teaspoon glycerin
  • Fragrance or essential oils
  • Colorant
  • Liquid soap

What You Do:

  1. Mix together the Epsom salt and sea salt in the mixing bowl.
  2. Add glycerin to the salt mixture and mix through. The glycerin is not necessary, but it helps the colorant and oil get dispersed evenly through the salt.
  3. Add a few drops of fragrance oils and a few drops of colorant. (Both of these items can be found at a local craft store.) We recommend getting skin-safe colorant from a craft store or else leaving out the colorant.
  4. Wet your hands with tap water, add a drop of soap to your hands, then rub them together to form a lather. Observe how much lather forms, then rinse off your hands.
  5. Fill a sink with water and add about an 1/8 cup of salt mixture to it. Use your hands to stir the water to help the salt dissolve. With your hands still wet from the salt water, add a drop of soap to your hands and rub them together to form a lather. How much lather formed this time?
  6. Store the rest of your salts in a jar, keeping the lid on tight to keep moisture out. Use about 1/4 cup of the salts in your bath.

What Happened:

You may have noticed that it was much easier to form lather (and more of it!) when using the water with salt rather than the water with no salt. This is because of the difference between hard water and soft water.

Most households in America have hard water. Hard water has a high mineral content, usually with calcium and magnesium, whereas soft water contains very little if any of these minerals. Generally, hard water is not a problem until it is used for cleaning purposes. Calcium and magnesium ions in the hard water—they react with the soap, forming insoluble gray flakes called soap scum rather than a lather. This results in more soap needed to get clean and the bathtub getting a grimy ring around it from the leftover soap scum. One way to soften hard bath water is to add bath salts. The calcium and magnesium ions in the water are replaced with sodium and potassium ions from the salt, allowing the soap to lather much more easily. (If your home has soft water, you may not notice too much of a difference in how well the soap lathers in the water with your bath salts and the water without the bath salts.)

Another benefit of adding salts to your bath has to do with osmosis. Osmosis is the movement of water through a membrane (such as your skin) to achieve equilibrium. Your body contains water and salt, whereas an ordinary bath contains mainly water and very little salt. Therefore, water will pass through your skin in an effort to balance the concentration of water and salt in you and in your bath. This excess water causes pruning. Adding bath salts to the water causes a more equal balance of salt and water in both you and in the bath, so less water enters your skin and less wrinkling occurs.

A Sliced Apple

Indoor Chemistry Project: How Does Acid Keep an Apple Fresh?

Apples and pears are great for snacks or to have as a side dish for dinner. But keeping them looking white and delicious after they have been sliced can be tricky. Try this experiment to see how chemistry can keep your apples and pears fresh even after they have been sliced.

What You Need:

  • An apple or pear
  • Sharp knife
  • Lemon juice
  • Clock
  • Adult help

What You Do:

  1. With adult help, cut the apple in half from top to bottom.
  2. On one apple half, lightly coat the white part of the apple with lemon juice. Leave the other half uncoated. (The uncoated half is your ‘control’ sample and lets you see what normally happens to a cut open apple.)
  3. Observe the color of both apple halves, then place them white-part-up on a counter or tabletop.
  4. Observe the apples again after 30 minutes. Notice any color changes and/or differences in appearance.
  5. Look at the apples again periodically throughout the day. What do you find?

What Happened:

When an apple is cut open, an enzyme called polyphenol oxidase is released from the cells of the apple and reacts with the oxygen in the air. This reaction causes the fruit to turn brown, similar to rust forming on metal. Almost all plants contain polyphenol oxidase, and it is believed plants use this enzyme as part of a defense mechanism. When a plant is damaged, the browning of the affected area is thought to discourage animals and insects from eating the plant any further. It also might help the plant heal because the browning creates an antibacterial effect, preventing germs from destroying the plant even more.

Lemon juice helps keep the apple from browning, because it is full of ascorbic acid (Vitamin C) and it has a low (acidic) pH level. Ascorbic acid works because oxygen will react with it before it will react with the polyphenol oxidase. However, once the ascorbic acid gets used up, the oxygen will start reacting with the enzyme and browning will occur. Lemon juice’s low pH level also helps prevent browning. Polyphenol oxidase works best when the pH level is between 5.0 and 7.0. However, below a pH level of 3.0, the enzyme becomes inactivated. The pH of lemon juice is in the 2.0 range, making it very effective against browning.

Besides lemon juice, lime juice and cranberry juice also have a pH below 3.0. Concord grape juice and grapefruit juice also have a low pH (not quite as low as the others), but will still help delay the browning process. You may want to try several of these juices and find a tasty to way to serve sliced apples and pears in the process!

Indoor Chemistry Project: Make a Colorful Bouncy Ball

Polymers are used to make numerous things, including clothing, plastic containers, nonstick cookware, and bulletproof vests. Try this experiment to see how polymers can make a toy.

What You Need:

  • 1 tablespoon white glue
  • 1/2 teaspoon borax
  • 1 tablespoon cornstarch
  • 2 tablespoons warm water
  • 2 plastic cups
  • 2 wooden craft sticks
  • Food coloring

What You Do:

  1. Pour the glue into one of the plastic cups. Add a few drops of food coloring to the glue and mix with one of the craft sticks until your desired color is achieved.
  2. In the second cup, combine the water and borax together and mix with the second craft stick. Stir until dissolved.
  3. Add the cornstarch and 1/2 teaspoon of the borax solution to the glue and let stand for 15 seconds.
  4. Stir with a craft stick until fully mixed together and the mixture becomes very difficult to stir.
  5. Mold the ball in your hands. It will be sticky at first but will become more solid as you roll it in your hands.
  6. You now have a bouncy ball. Try bouncing it. How high does it go? Store your ball in an airtight container or Ziploc bag so it doesn’t dry out and crumble.

What Happened:

The white glue contains polyvinyl acetate, a strong and flexible polymer that gives the ball strength. Cornstarch contains amylopectin, a polymer whose shape is best described as ‘branched’—it sticks out like the branches of a tree—and gives the ball the property of elasticity. Elasticity allows the ball to return to its original shape after being compressed or stretched, such as when it hits the floor. So instead of splattering everywhere, the ball bounces back up. The borax is needed to help the glue and the starch stick together. This connects the two polymers into a net-like formation, keeping the ball from crumbling or becoming slime when you bounce it.

Indoor Chemistry Project: Make Scented Gel Air Fresheners

Polymers have numerous uses and have made our lives much more comfortable. One way is to help make your home smell fresh.

What You Need:

  • Unflavored gelatin
  • Water
  • Fragrance oil
  • Food coloring
  • Table salt
  • Small jars

What You Do:

  1. Boil one cup of water and stir in four packages of gelatin until dissolved. Remove from heat and add in one cup of cold water.
  2. Add about 10 to 20 drops of the fragrance oil to the gelatin. If you would like, add a few drops of food coloring as well.
  3. Add one tablespoon of salt to the gelatin mixture to keep mold from growing.
  4. Carefully pour the gel into the small jars. Allow the gel to set either at room temperature or in the refrigerator.
  5. Set them around your home and smell the fragrance coming from them.

What Happened:

Gel air fresheners are able to scent the air for a long time because gelatin is a polymer. Specifically, the polymer is collagen, a protein that forms a matrix type structure, allowing the gelatin to hold its shape. The fragrance oil particles are suspended in the matrix of the gel, which keeps the scent trapped inside. As the gel evaporates, the scent particles are released from the matrix, causing a continuous scent to be released from the air freshener.

From the Archives: More Fun Indoor Chemistry Projects

Science Links

Play this game to learn about which elements are used in items around the house.