Category Archives: Science Projects

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

Borax Crystal Heart Science Project

Borax Crystal Heart

Borax Crystal Heart

Grow borax crystals overnight to make a beautiful sparkling crystal heart. Use the borax crystal heart as a decoration or simply grow it as a fun crystal project.

Borax Crystal Heart Materials

  • borax
  • water
  • pipecleaner

Make a Borax Crystal Heart

  1. Shape the pipecleaner like a heart. It’s fine to have a ‘stem’ at the bottom of the heart, since this will give you a way to suspend the heart in the crystal growing solution. You can always clip it later with scissors or wire cutters.
  2. Prepare the crystal growing solution by stirring borax into boiling hot water until it stops dissolving. You can tell you have enough borax if a little powder starts to accumulate in the bottom of the container.
  3. Add food coloring, if desired. Alternatively, if you want a colored heart you can simply use colored pipecleaners.
  4. Place your heart shape into a container. It’s best if the heart doesn’t touch the sides or bottom of the container, which you can achieve by hanging the heart from a pencil or butter knife. However, you’ll get decent results just setting the heart into the container. 
  5. Pour the borax crystal solution into the container, being certain all of the heart is covered. Try to avoid getting any undissolved solid into this container.
  6. Allow the crystals to grow on the heart for several hours or overnight. When you are satisfied with the crystals on the heart, remove it from the crystal solution and allow it to dry. You can hang the heart as a decoration. The crystal heart may be stored wrapped in tissue paper.

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

Fire Breathing Dragon – Halloween Pumpkin

This carved Halloween dragon pumpkin breathes real smoke and fire. Photo Credit: Anne Helmenstine

This carved Halloween dragon pumpkin breathes real smoke and fire. Photo Credit: Anne Helmenstine

Carve a dragon jack o’ lantern for Halloween and make your pumpkin breathe real smoke and colored fire. The fire breathing dragon is easy to do and quite spectacular.

Dragon Pumpkin Materials

  • real pumpkin (fake might catch fire!)
  • dragon pattern
  • knife
  • red sparklers or emergency flare

Carve the Dragon

  1. Cut around the top of the pumpkin, slanting inward so the top of the pumpkin won’t fall inside the jack o’ lantern.
  2. Scoop the seeds out of the pumpkin If you like, bake the pumpkin seeds as a treat.
  3. Print out the free pattern and tape it over the pumpkin. It’s easiest to stick the tape if the pumpkin skin is dry.
  4. If you are a pumpkin carving master, carve away! Otherwise, it’s easier to prick the outline of the pattern into the pumpkin using a knife tip or toothpick. When you complete the outline, remove it and carve the face. To really make the features pop, go back and carve away a little pumpkin flesh from the edges of the dragon. Light can pass through the thin sections, so the design will show up better.

Make the Dragon Breathe Smoke and Fire

You can put a red glow stick or regular pumpkin light inside the candle to get a nice rosy glow, but when you’re ready to kick it up a notch, it’s easy to make this dragon breathe fire. The red fire comes from heating a strontium-based salt, which emits crimson light. Although the photo was taken in my living room, it’s probably a good plan to complete these steps outdoors. Either sparklers or a flare will evolve a lot of smoke. You can:

  • Place a red sparkler (or a few) head-down in the pumpkin. Use a long-handled lighter to ignite them. This is a relatively short-lived effect, but you can always add more.
  • Place an emergency road or boat flare in the pumpkin and light it. This effect can last for quite a while, depending on the flare. It’s very bright.
  • Break open a flare and pour a small amount of the powder inside the flare. Ignite it to get smoke and red fire. You can mix the flare with another fuel (e.g., wood chips) to dim the brilliance of the flare and extend the life of the display.

Glowing Hand of Doom Halloween Punch Recipe

This festive punch has a glowing hand and gives off lots of fog. It tastes great, too!. Anne Helmenstine

This festive punch has a glowing hand and gives off lots of fog. It tastes great, too!. Anne Helmenstine

Glowing Hand of Doom punch is a great punch for Halloween parties or mad scientist parties. Here’s how to make a glowing hand rise from the punch, which is bubbling and producing fog.

Glowing Hand of Doom Punch Ingredients

  • disposable glove, not powdered
  • tonic water
  • dry ice
  • punch (cran-grape cocktail works great)
  • black light

Make the Punch

  1. Rinse the glove with water. Fill the glove with tonic water. Hang it in the freezer to freeze it. I set mine on a box of ice cream to suspend it, held in place with a frozen pizza on the edge of the glove. Be careful not to mash the glove when the door closes or else the hand will be disfigured. 
  2. When the tonic water is frozen in the glove, set the glove in a large glass bowl or punch bowl. You should be able to get it to stand on its own without too much trouble, otherwise you can set it upright in a glass, placed inside the punch bowl. It isn’t necessary to remove the hand from the glove. You can dribble a little red food coloring on the hand if you want it to appear bloody. 
  3. Pour your punch into the punch bowl. As the dry ice sublimates, it will carbonate your punch. Cran-grape cocktail makes a nice bloody-looking punch that tastes good carbonated. Orange-pineapple cocktail makes a nice orange Halloween punch. If you mix juice with tonic water then the punch itself will glow under a black light
  4. When it’s time for your party, add dry ice to the punch. The dry ice will sink, so there isn’t much risk of getting any into a cup when the punch is served. You can use regular ice if you want your drinks to be colder. Feel free to add more dry ice over time. 
  5. Black light (ultraviolet) will make the hand glow. Dry ice causes the bubbling. It’s perfectly safe to drink the punch, but don’t drink the pieces of dry ice (they are easy to avoid while serving the beverage).

Brown Ink Recipe – Easy Chemistry Project

Brown Ink (Cody and Maureen, Flickr)

Brown Ink (Cody and Maureen, Flickr)

It’s very easy to make your own natural brown ink for writing, drawing, or crafts. Here is a brown ink recipe you can try.

Brown Ink Ingredients

  • 4 teaspoons loose tea or 4-5 teabags
  • 1 teaspoon gum arabic
  • 1/2 cup boiling water

Prepare the Brown Ink

  1. Pour the boiling water over the tea. Allow the tea to steep for about 15 minutes.
  2. Squeeze as much tea (tannin) as possible from the tea or teabags.
  3. Stir in the gum arabic.
  4. Strain the ink and allow it to cool before bottling it.

While the tannin in tea is particularly excellent for ink, you could use coffee grounds or nut shells. You can use herbal teas to obtain inks in other colors. Expect the color of the ink to change over time or after prolonged exposure to heat or sunlight.

Use Chemistry to Make Other Ink Colors

Apply a bit of chemistry to make other colors of inks. This video explains simple methods of making black, brown, blue, and red inks.