Category Archives: Chemistry Projects

Cool Electroactive Slime That Reacts to Styrofoam

Electroactive slime is a opaque slime that reacts to static electricity. (Josh Hallett)

Electroactive slime is a opaque slime that reacts to static electricity. (Josh Hallett)

This recipe makes cool, non-toxic slime that appears to have a life of its own! It’s electroactive slime, so it reacts when it’s close to electrically charged objects. Rub a piece of polystyrene foam or a balloon on your hair or a wall to charge it and observe how the slime reacts.

Difficulty: Average

Time Required: 30 minutes

Electroactive Slime Materials

  • 3/4 c cornstarch (175 mL)
  • 2 c vegetable oil (475 mL)
  • glass or tumbler
  • refrigerator
  • 1x6x6 inch (25x150x150 mm) styrofoam

How To Make Electroactive Slime

  1. Mix the cornstarch and vegetable oil together in the glass.
  2. Refrigerate the slime mixture until it is chilled.
  3. Remove from the refrigerator and stir (separation is normal).
  4. Allow the mixture to warm enough so that it can flow.
  5. Take a block of styrofoam and charge it by rubbing it on hair, wool, or a cat.
  6. Tip the container of slime (which should flow slowly). Place the charged styrofoam about an inch (2 cm) from the flowing slime. It should stop flowing and seem to gel!
  7. If you wiggle the charged styrofoam the slime may follow or pieces of it may even break off.
  8. When the styrofoam is removed the slime will continue to flow.
  9. After use, refrigerate slime in a sealed container.

Be sure to try other slime recipes, too!

See Electroactive Slime in Action

Here’s a variation of the recipe that shows how the slime reacts with static electricity. If she had refrigerated her slime, it would be more “slimy”. The slime has a life of its own whether it’s chilled or not:

Super Easy Soap Slime Recipe

Use translucent glycerin soap to make soap slime you can see through. (darwin Bell)

Use translucent glycerin soap to make soap slime you can see through. (darwin Bell)

Soap slime is an easy-to-make type of slime that is fun to play with and makes clean-up fun. Here’s how you make it.

Soap Slime Materials

  • leftover pieces from bars of soap (or you can use a whole bar)
  • water
  • jar

Make Soap Slime

You’ve probably made soap slime accidentally by allowing soap to get wet and stay wet in the bathtub or shower. Here’s how you make soap slime, on purpose:

  1. Place the soap pieces in a jar.
  2. Cover the soap with water.
  3. Let the jar sit for a day or two. You’ve got slime!

You can play with the slime or you can use it during bath time like you would ordinary soap. The soap slime with rinse away with water. Soap isn’t edible, so don’t eat this slime either. Also keep it out of your eyes. If you get some soap slime in your eyes, immediately rinse it out with water. Otherwise, have good clean fun!

Make Dish Soap Slime

Another cool type of soap slime to make uses dish soap. The ingredients for this slime are:

  • liquid dish soap (choose the color you want the slime to be)
  • glitter
  • clear non-toxic glue (PVA or polyvinyl alcohol school glue)
  • salt water or saline solution (although you’ll get better results using borax in water)

Make a Color Change Liquid Thermometer

Cobalt(II) chloride may appear either pink or blue in solution, depending on which ion is formed. (Chemicalinterest)

Cobalt(II) chloride may appear either pink or blue in solution, depending on which ion is formed. (Chemicalinterest)

This color change chemistry project will give you a liquid that fluctuates between pink and blue as the temperature changes. In essence, it’s a color change thermometer.

What You Need

  • beaker or attractive clear container
  • 3 g cobalt(II) chloride hexahydrate (also known as cobaltous chloride hydrate)
  • 500 ml alcohol

Prepare the Solution

  1. Mix 3 grams of cobalt(II) chloride hexahydrate in alcohol.
  2. The pink solution will turn blue as it is heated and will return to the pink color as the solution cools.
  3. Alternatively, heat the solution until it it is just slightly warmer than room temperature. Add water dropwise until the blue solution turns pink. This solution will be extremely sensitive to color changes near room temperature.

How It Works

Aqueous solutions of hydrated cobalt chloride are pink, but formation of [CoCl4]2- produces a blue color. Addition of hydrochloric acid to an aqueous cobalt(II) chloride solution will change the solution from pink to blue as will temperature change of the alcohol solution. This presumably occurs because the amount of water attached to the cobalt ion changes as you vary the temperature of the alcohol solution.

Rainbow WandMake Violets Change Color

Make a Safe Homemade Lava Lamp

You can make your own lava lamp using safe household ingredients. Anne Helmenstine

You can make your own lava lamp using safe household ingredients. Anne Helmenstine

Lava lamps are interesting and cool. Have you ever wanted to make your own cool oozing display? Lava lamps that you buy use high heat and toxic chemicals, but you can make a lava lamp at home using safe kitchen ingredients. Here’s how:

Materials

This project results in a non-toxic lava lamp that is safe for kids to make and use.

  • 1-liter plastic bottle
  • vegetable oil
  • water
  • food coloring
  • Alka Seltzer tablets

Make a Lava Lamp

  1. Fill the bottle most of the way full with vegetable oil.
  2. Add about a tablespoon of water.
  3. Drip in a few drops of food coloring.
  4. Break an alka seltzer tablet into pieces and add them to the bottle.
  5. Seal the cap on the bottle.
  6. After the reaction is complete, you can break and add another alka seltzer tablet to make more bubbles.
  7. Feel free to shine a flashlight on the bubbles to add the ‘light’ part of a traditional lava lamp.

I made a lava lamp video of this project so you can see what to expect.

Color Change Violets Chemistry Demonstration

The color change violets project works because violets are natural pH indicators.  (Robert & Pat Rogers)

The color change violets project works because violets are natural pH indicators. (Robert & Pat Rogers)

You can change violets from violet to green by exposing them to a household chemical. This is a fun chemistry demonstration, especially for the home.

Color Change Violet Materials

  • violets
  • household ammonia

Change the Color!

Really, nothing could be easier. Hold violets over ammonia and watch them change from blue or violet to green. You can speed the reaction if you use warmed ammonia or you can dip the flowers in the ammonia. The demo used to be performed as a sort of ‘trick’ using ammonia gas, which produces a quick and dramatic color change. With ordinary household ammonia, you can expect the color change to take a couple of minutes.

How It Works

Flowers, including violets, get their color from anthocyanins. This is a class of pigment molecules that changes color in response to pH. Ammonia is very basic, so it changes the blue color of violets to green. Violets come in other colors besides… well… violet, so expect a color change for these flowers too. The final color might not be green. For example, I tried this project using orange pansies (a form of violet) and got sort of a dull greenish-yellow color as a final result. Also, you can experiment with other flowers to get a color change in response to ammonia.

Learn More

Odor of Violets Chem Demo
Make a pH Rainbow Tube

Mercury Beating Heart Chemistry Demonstration

Mercury is a heavy silvery metal that is liquid at room temperature. In the Mercury Beating Heart experiment, a drop of mercury pulsates rhythmically, like a beating heart. Femto/Elementbox04

Mercury is a heavy silvery metal that is liquid at room temperature. In the Mercury Beating Heart experiment, a drop of mercury pulsates rhythmically, like a beating heart. Femto/Elementbox04

The mercury beating heart is a popular chemistry demonstration based on an an electrochemical redox reaction that causes a blob of mercury to oscillate, resembling a beating heart. Here’s how the Mercury Beating Heart works and how you can perform this chemistry demonstration yourself.

Mercury Beating Heart Overview

A drop of mercury is placed in a watch glass. The mercury is covered with a solution of an oxidizing compound in sulfuric acid. The oxidizer usually is potassium dichromate, hydrogen peroxide or potassium permanganate. An iron nail or wire is placed such that the tip of the nail is almost touching the mercury. The mercury will begin to pulsate rhythmically, like a beating heart.

Perform the Mercury Beating Heart Demo

  1. Place a drop of mercury in a watch glass, petri dish or saucer. 
  2. Pour sulfuric acid over the drop to cover it. The exact concentration of sulfuric acid is not critical. Car battery acid works for this demo. 
  3. Add a small amount of oxidizer, such as potassium permanganate, hydrogen peroxide or potassium dichlorate. Aqueous solution or a few crystals are fine. 
  4. When you are ready to start the beating heart, approach the drop of mercury with the tip of the iron wire or nail. The heart will start to beat when the iron is close to the mercury, but not quite touching it. The mercury heart will beat for about 20 seconds before stopping.

How the Mercury Beating Heart Works

The mechanism for this reaction is not clearly understood, but it may involve oxidation of the iron. The permanganate, peroxide or dichromate oxidizes the mercury to produce mercury(I) ions which combine with sulfate ions from the sulfuric acid to form a thin layer of mercury(I) sulfate on the surface of the drop of mercury. The formation of the layer reduces the surface tension of the drop, causing it to flatten out. When the flattened drops contacts the iron wire or nail, the mercury sulfate oxidizes the iron to form the iron(II) ion while reducing the mercury to its normal metallic form. The mercury has a higher surface tension, so the drop becomes rounded again. As contact with the iron ceases, the oxide coating starts to form again, repeating the process. When all of the oxidizer has been reduced, the reaction stops. There is some debate about the mechanism because weaker oscillations have been observed even without the presence of oxidizer.

Less Toxic Alternative to Mercury

Mercury is very toxic, so you may wish to perform this demonstration with another material. It turns out molten gallium may be substituted for the drop of mercury. Gallium will melt at a low temperature and is much less toxic/easily contained than mercury. To perform the demonstration with gallium, melt a pellet of gallium and immerse it in sulfuric acid. Add a small amount of an oxidizer, such as potassium permanganate, to the sulfuric acid. The gallium heart will be more slowly than the mercury heart.

Watch the Mercury Beating Heart in Action

It’s much safer to watch a video of this demonstration than to do it yourself. Here’s what happens…

 

Hollow Penny Science Project

Make a hollow penny by dissolving away the zinc to leave copper metal. (United States Mint)

Make a hollow penny by dissolving away the zinc to leave copper metal. (United States Mint)

This is an easy chemistry project that uses common materials. You take a post-1982 penny, score the copper surface to expose the zinc interior, react the zinc with acid, and are left with a hollow copper penny.

Hollow Penny Materials

  • post-1982 US pennies (metal composition changed in this year)
  • muriatic acid (from a hardware store)
  • a disposable plastic container or glass jar
  • baking soda (sodium bicarbonate)
  • water

Time Required: 6 hours

Here’s How:

  1. You need to expose the interior of the pennies. You can score the edge of the pennies with a file or snip them with wire cutters, but I think the easiest way to expose the zinc is to rub the edge of each penny along a brick or concrete block. You could use sandpaper, if it’s available. Use whatever is handy to expose some of the zinc (don’t go all the way around the coin). If you can see silver metal under the copper of the penny, you’re ready to proceed to the next step.
  2. It’s best to do this step outdoors or under a fume hood, wearing gloves and protective eyewear. Read the safety precautions on the muriatic acid container. Basically, this is hydrochloric acid. Treat it with respect. Place the pennies in your container. Pour a little muriatic acid over the pennies so that they are covered. Bubbles will start to form immediately. Set the container somewhere where it will be safe from spills, children, and pets. Let the reaction proceed for about 6 hours.
  3. Carefully pour off the muriatic acid. You can wash it down a drain, providing you use a lot of water.
  4. Fill the container with water. Add a little baking soda to neutralize the residual acid.
  5. Examine your penny. The hollow penny will be a fragile copper foil.

See How to Make a Hollow Penny