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Anne Marie Helmenstine, Ph.D.

Anne Marie's Chemistry Blog


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Gallium Beating Heart

Thursday April 24, 2014
Liquid gallium crystallizing (Tmv23 & dblay)The mercury beating heart experiment involves placing a blob of mercury into some acid, adding an oxidizer and approaching the mercury with a piece of iron. An electrochemical reaction causes a compound to form and dissipate on the mercury, changing its surface tension and causing it to tense and relax, much like a beating heart. While it's a fascinating chemistry or physics experiment, the mercury is highly toxic, so you may be interested to know the beating heart also may be performed using gallium.

Gallium Beating Heart Materials

The gallium beating heart is set up much like the mercury beating heart, except an iron nail or wire need not be used. You will need:
  • small piece of gallium
  • dilute sulfuric acid (e.g., battery acid)
  • a small amount of oxidizer (such as potassium dichromate or potassium permanganate)

Perform the Gallium Beating Heart Experiment

This reaction is dependent on getting the ratio between the acid and the oxidizer just right, so expect some trial and error.
  1. Melt the bit of gallium using the warmth of a gloved hand. Set the gallium in a watch glass or petri dish.

  2. Pour acid into the dish to cover the gallium.

  3. Add a small amount of oxidizer to the dish. You'll see an immediate reaction from the gallium. Wait to see whether the gallium heart "beats". If it does not, add a bit more oxidizer.
The gallium beating heart will beat more slowly than the mercury beating heart. Since you'll be playing with the acid and oxidizer volumes, you can expect an irregular heartbeat, too. Still, it's a nice alternative to having to clean up mercury, right? If you've tried this project and have any comments or suggestions, please post a response.

Top Chemistry Demos | Demonstrations - Reader Favorites

Why Does the Pool Turn Blonde Hair Green?

Thursday April 24, 2014
Swimming pool water may turn your hair green. (Phaedra, morguefile.com)I'm not blonde, but I was as a kid. After a few weeks of summer, my hair would turn from blonde to pale green. Why? I always thought it was from the chlorine in the local swimming pool. As it turns out, the pool was the culprit, but it wasn't because of the chlorine. Do you know the cause of green swimming pool hair?

Is It Safe to Reboil Water?

Wednesday April 23, 2014
Reboiling water may be bad for your health. (Markus Schweiss)You may have heard that is is unhealthy to reboil water or even to boil it away when cooking. Unless your water is exceedingly pure, reboiling water drives off the gases dissolved in the water and evaporates away some of the water, concentrating minerals and contaminants. There are two safety concerns with reboiling water. The first is that reboiling water increases the chance you'll get burned. With the gas bubbles removed, reboiling water can cause it to superheat and suddenly splash out when disturbed. The other safety issue concerns the chemical composition of reboiled water. Is it unhealthy? Find out more

Grow a Cup-o-Crystals

Wednesday April 23, 2014
Cup-o-Crystals (Anne Helmenstine)From my list of quick crystal projects, here's a favorite. This one takes a minute to set up, yielding a mass of needle-like crystals after about three hours in your refrigerator. All you need is a cup or small, narrow bowl, epsom salts, and water. Grow Crystals in a Cup...

Darvaza Gas Crater - Extremely Cool Fire Tourist Attraction

Tuesday April 22, 2014
Darvaza Gas Crater (Getty Images)

Have you heard of the Darvaza Gas Crater or The Burning Gate to Hell? It is a massive burning crater that resulted from a natural gas accident that occurred in either the 1950s or else 1971, depending on who tells the tale. The drilling rig fell into a natural cavern, which was set alight. It still burns today. I don't see myself planning a vacation to the Karakum desert in Turkmenistan anytime soon, but if I went there, I would be sure to check this out. Photos of the Darvaza Crater are stunning. There are also some YouTube videos of the so-called "Door to Hell" out there. Pretty cool, don't you think?

Happy Earth Day!

Tuesday April 22, 2014
Happy Earth Day! The purpose of the day is to inspire appreciation for the earth's environment and awareness of issues that threaten it. With that in mind, here's a look at some environment-related chemistry. I selected features that focus on cool features of the environment, like snowflakes and changing leaves, as well as issues, such as the greenhouse effect and fluoridation of drinking water.Photo: NASA image, featured on the unofficial Earth Day flag.

This Day in Science History - April 22 - Rita Levi-Montalcini

Monday April 21, 2014
Rita Levi-Montalcini April 22ndis the birthday of Rita Levi-Montalcini. She was awarded half the 1986 Nobel Prize in Medicine for the discovery of nerve growth factors. Upon graduation in 1936 with a medical degree, she was denied an academic or professional position in her native Italy under Mussolini's anti-Jewish laws. Instead, she set up a home laboratory in her bedroom and began researching nerve growth in chicken embryos. The paper she wrote on chick embryos earned her an invitation to a research position at Washington University in St. Louis, Missouri in 1947 where she stayed for the next 30 years. The Italian government recognized her by making her a member of the Italian Senate for life in 2001. She was a respected and active member of the Senate until her death in 2012 at the age of 103.

Today was a busy day in the history of science. Find out what else occurred on this day in science history.

Go Green for Earth Week - Make Your Own Shampoo

Monday April 21, 2014
One of the biggest reasons to make your own shampoo is to avoid unwanted, potentially toxic chemicals. Another reason you might want to make your own shampoo is so you can customize the formulation for your hair's needs and your preference for fragrance (or lack of fragrance). Here's a recipe for a gentle vegetable-based shampoo. It's similar to my earlier shampoo recipe except this one uses potassium hydroxide instead of lye, which produces a shampoo that lathers better and rinses more easily. Mix the shampoo in a well-ventilated room or outdoors and be sure to read all of the safety precautions on the ingredients. Readers have recommended triethanolamine or diethanolamine in place of sodium hydroxide or potassium hydroxide. Choose the formulation that works best for you.

Shampoo Ingredients

  • 2 lb 10 oz olive oil
  • 1 lb 7 oz of solid-type vegetable shortening
  • 1 lb coconut oil
  • 14.4 oz potassium hydroxide
  • 2 pints water
  • 1-1/2 oz glycerine (glycerol)
  • 1/2 oz ethanol
  • 1-1/2 oz castor oil
  • essential oils (optional), such as peppermint, rosemary, lavender, for fragrance and therapeutic properties
Let's Make Shampoo!
  1. In a large pan, mix together the olive oil, shortening, and coconut oil.

  2. In a well-ventilated area, preferably wearing gloves and eye protection in case of accidents, mix the potassium hydroxide and water. Use a glass or enameled container. This is an exothermic reaction, so heat will be produced.

  3. Warm the oils to 95°F-98°F and allow the potassium hydroxide solution to cool to the same temperature. One of the easiest ways to accomplish this is to set both containers into a large sink or pan full of water that is at the correct temperature.

  4. When both mixtures are at the proper temperature, stir the solution into the oils. The mixture will turn opaque and may darken.

  5. When the mixture has a creamy texture, stir in the glycerine, alcohol, castor oil, and any fragrance oils or colorants.

  6. You have a couple of options here. You can pour the shampoo into soap molds and allow it to harden. To use this shampoo, either lather it with your hands and work it into your hair or else shave flakes into hot water to liquefy it.

  7. The other option is to make liquid shampoo, which involves adding more water to your shampoo mixture and bottling it.
You can make your homemade shampoo pearlescent if you add a little glycol distearate, a natural wax derived from stearic acid. The tiny wax particles reflect light, causing the effect.

This Day in Science History - April 21 - Hertwig and Flemming

Sunday April 20, 2014
April 21st is the birthday of two important scientists in the field of cell biology. Oskar Hertwig was the first to pinpoint when fertilization occurs between sperm and ovum cells and Walther Flemming was the scientist who observed the behavior of chromosomes in the nucleus during cell mitosis. Both discoveries were major events in late 19th century biology.

Find out what else occurred on this day in science history.

Why Do Clothes Wrinkle?

Sunday April 20, 2014
Ironing Clothing (Getty Images)I think the only good thing about old permanent press fabrics is that they tended to disintegrate pretty quickly so you never had to wear them for long. They were itchy, smelly, and toxic, thanks to the presence of formaldehyde in the treatment that made them wrinkle-free (much like flame retardant clothing in those respects). Of course, modern wrinkle-free fabrics aren't nearly as heinous as their predecessors. Advances in polymer chemistry have led to significant improvements.

The key to both the cause of wrinkling and its solution lies in understanding chemical bonds. Wrinkles form when you break chemical bonds within fabric polymers and then reform them when the fabric is crumpled up. You can break bonds by heating fabric. Other polymers use hydrogen bonding, so getting those materials wet allows the hydrogen bonds in water to restructure the molecules. When you press clothes with a steam iron, you have both heat and water, so you can effectively remove wrinkles. Usually you can prevent them from forming in the first place, even with non-permanent press fabrics, by using a dryer with a cool down cycle and making sure the dryer runs long enough that your clothes are completely dry before the cycle stops.

Why Clothes Wrinkle | How Disposable Diapers Work
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