Hands-on-science: Make old pennies new again

July 18th, 2011

Have you seen rust on metals? Have you noticed rust on the old bridges? Or even old tools? Here is another fun activity that can be tried with basic household objects with your kids to teach them basics of metal reactivity.


What do you need?

  • 20 dull, dirty pennies
  • 1/4 cup white vinegar
  • 1 teaspoon salt
  • A clear, shallow bowl (not metal)
  • 2 clean steel nails
  • 1 clean steel screw
  • Paper towels

Caution

Be careful with the nails and screws!

Instructions

PART 1

  1. Put salt and vinegar in the bowl. Stir until the salt dissolves.
  2. Put one penny half way in the liquid and hold for 10 seconds.  Take it out of water. What do you see?
  3. Dump all the pennies in the bowl.  You will see them change color for few seconds and then it stops.
  4. Wait 5 minutes and take half of the pennies out of the liquid. Put them on the paper towl to dry.
  5. Take the rest of the pennies out of the bowl and rinse them very well under the running water. Put them on another paper towel that is marked “Rinsed”.
  6. After about an hour, look at the pennies on the paper towels.  What’s happened to the ones you rinsed? What’s happened to the others? What color is the paper towel under the unrinsed pennies?
  7. Keep the liquid for Part 2 of this excercise.

What’s happening?

Rust is scientifically called oxidation, which occurs when oxygen comes in long-term contact with certain metals.  Over time, the oxygen combines with the metal at an atomic level, forming a new compound called an oxide and weakening the bonds of the metal itself.  If the base metal is iron or steel, the resulting rust is properly called iron oxide.  Rusted aluminum would be called aluminum oxide, copper forms copper oxide and so on.

Why did the pennies look dirty before I put them in the vinegar?

Everything around you is made up of tiny particles called atoms. Some things are made up of just one kind of atom. The copper of a penny, for example, is made up of copper atoms. But sometimes atoms of different kinds join to make  molecules. Copper atoms can combine with oxygen atoms from the air to make a molecule called copper oxide. The pennies looked dull and dirty because they were covered with copper oxide.

Why did the vinegar and salt clean the pennies?

Copper oxide dissolves in a mixture of weak acid and table salt-and vinegar is an acid. You could also clean your pennies with salt and lemon juice or orange juice or tomato ketchup, because those juices are acids, too.

Why did the unrinsed pennies turn blue-green?

When the vinegar and salt dissolve the copper-oxide layer, they make it easier for the copper atoms to join oxygen from the air and chlorine from the salt to make a blue-green compound called malachite.

If you want to oxidize a new copper yourself, you can follow these instructions.

PART 2

  1. Put a nail and a screw into the bowl with liquid. Immerse another nail half way into the liquid by leaning it to the side of the bowl.
  2. After 10 minutes, look at the color of the nails. Are they different color than before?  Is the leaning nail 2 different colors? If not, leave the nails in the bowl and check on them in another hour or so.
  3. What’s happening to the screw? You may see fizzing bubbles coming from the screw.  Leave it in the liquid for a while to see what happens.

What’s happening?

Why did bubbles come off the steel screw?

Each water molecule is made up of two hydrogen atoms and an oxygen atom. In an acid (like vinegar or lemon juice), lots of hydrogen ions (hydrogen atoms that are missing an electron) are floating around. In the chemical reactions at the surface of the screw, some of these hydrogen ions join and form hydrogen gas. The bubbles that you see coming off the screw are made of hydrogen gas.

How did the nail and the screw get coated with copper?

To understand how the nail and screw got coated with copper, you need to understand a little bit more about atoms. Atoms are made up of even smaller particles called protons, neutrons, and electrons. Electrons and protons are both electrically charged particles. Electrons are negatively charged and protons are positively charged. Negative charges attract positive charges, so
electrons attract protons.

When you put your dirty pennies in the vinegar and salt, the copper oxide and some of the copper dissolve in the water. That means some copper atoms leave the penny and start floating around in the liquid. But when these copper atoms leave the penny, they leave some of their electrons behind. Rather than having whole copper atoms in the liquid, you’ve got copper ions, copper atoms that are missing two electrons. These ions are positively charged.

Now add two steel nails and a screw to the mixture. Steel is a metal made by combining iron, other metals, and carbon. As you found out when you cleaned your pennies, your mixture of salt and vinegar is really good at dissolving metals and metal oxides. When you put the steel nail in the mixture, some of the iron dissolves. Like the copper atoms, each of the iron atoms that dissolves leaves two electrons behind. So you’ve got positively charged iron ions floating in your vinegar with the positively charged copper ions.

Originally, the steel nail was neutrally charged-but when the iron ions left their electrons behind, the nail then became neg-atively charged. And remember what we said way back at the beginning of this section: negative charges attract positive charges. The negative charges on the nail attract positive charges in the liquid. Both the iron ions and the copper ions are positively charged. The copper ions are more strongly attracted to the negative charge than the iron  ions, so they stick to the negatively charged nail, forming a coating of copper on the steel.

This activity is courtesy of Exploratorium.

Microsoft Imagine Cup 2011

July 15th, 2011

Wow, it is great to cover two great STEM related competitions / challenges within the same week.   Meet the 2011 Imagine Cup winners at the Imagine Cup website.

Imagine Cup 2011

Hands-on-Science: Make your own salt volcano

July 14th, 2011

What do you need?

  • Glass Jar or Clear Drinking Jar
  • Glass
  • Vegetable Oil
  • Salt
  • Water
  • Food Coloring (Optional)

Caution

Be careful with the glass

Instructions

  1. Pour about 3 inches of water into the jar
  2. Pour about 1/3 cup of vegetable oil into the jar. When everything settles, is the oil on the top of water or underneath it?
  3. (Optional) Add one drop of food coloring to the jar. What happens? Is the drop in the oil or in the water? Does the color spread?
  4. Shake salt on top of oil while you count slowly to 5.
  5. Add more salt to keep the action going for as long as you want.

To see the science behind this activity, go to Exploratorium Science Explorer.

What did you learn?

DENSITY – Low density liquids will rise above the higher density liquids

While water often mixes with other liquids to form solutions, oil and water does not. Water molecules are strongly attracted to each other, this is the same for oil, because they are more attracted to their own molecules they just don’t mix together. They separate and the oil floats above the water because it has a lower density.  The food coloring only mixes with the water and goes through the oil to reach the water.

Real World Applications

Variation

Would you like to make your Lava Lamp bubble? How would you do that?

  1. Get a glass jar with lid or a tube and fill it 3/4 full with oil (use some cheap vegetable oil).
  2. Add couple of tablespoons of water to the tube.
  3. Add 10 drops of food coloring.
  4. Divide an Alka-Seltzer tablet into 4 pieces.
  5. Drop one piece into the oil and water mixture.  What happens?
  6. When the bubbling stops, screw the soda bottle cap on and seal with duct tape. Be sure the bubbling totally stops.  Did you notice the fizz? This will take a few minutes. Turn the test tube slowly back and forth to see your lava lamp flow.

Oil and water molecules are so attracted to themselves that they do not mix together, even though they will mix with other substances. Oil has a lower density than water so it floats on top. The food coloring only mixes with the water and goes through the oil to reach the water. The alka-seltzer reacts with the colored water to make bubbles of carbon dioxide gas. These bubbles attach themselves to the blobs of food colored water and causes them to float to the surface. When the bubbles pop and the carbon dioxide escapes, the blobs sink back to the bottom.

Tech companies investing in STEM

July 14th, 2011

It’s nice to see big technology companies like Google investing in STEM education through various science related contests.  In the 2011 Google Science Fair, three amazing girls were the top three winners.   The presentations prepared by these kids were very high quality and consisted of presentations, interviews and videos.  Check out the finalists with their project descriptions at: http://www.google.com/events/sciencefair/finalists.html.

Congratulations future scientists!!

Science Model Building Day at Uncle Games

March 7th, 2011

I organized a small event at Uncle Games in Redmond this week.   I personally like visiting Uncle Games for wide variety of games they offer for kids of all ages.  They have this little area at the back of the store , where they give you demonstrations of up-and-coming games.

Since there wereuple of age groups: Grade 1 & Grade 7+, we had two activities going on in parallel.  Jon, one of the King County Science Club’s member brought his son’s computer and showed how to put it together from all the computer parts.  I led the other activity with the younger kids and showed them how to make a membranophone from a water bottle, gloves and straw.  The kids had fun making it and learning about the principles of how a set of vibrations to a membrane (stretched glove in our experiment) produce sound.

If you want to try the experiment at home, follow the link below to create your water bottle mebranophone and have fun making some music.

http://www.exploratorium.edu/afterschool/activities/index.php?activity=139

 

Building electronic devices, anyone?

January 30th, 2011

Would you like to build your own electronic devices? Sounds hard … it doesn’t need to be.  Now, you can buy small hardware modules that you can just connect together to prototype a device in a matter of hours (not days and weeks).   The type of devices include Mp3 players, environmental monitor, bike computer, cameras that send information to other devices, … your imagine it and you can build it … easily! :-)

With Microsoft .NET Gadgeteer, you can do just that without necessarily requiring an advanced engineering degree.  You still ofcourse some passion to put things together and be able to have interest in learning to program.  These devices can be programmed using Microsoft Visual Studio development environment, as the Gadgeteer is built over Microsoft .NET Micro-Framework.

Colin Miller, the Product Unit Manager of this product at Microsoft kindly provided us an early demo of this product to a group of science enthusiasts.  It was a small event attended by teenagers and adults.   In this demo, Colin walked us through the capabilities of .NET Gadgeteer and programmed a simple switch on/off device.   I personally was very inspired by it!  You can find more details about this cool technology at http://netmf.com/gadgeteer/.

 

 

 

 

 

 

All the cool modules, Colin brought with him.  He passed them around to us so we could see all the tiny text written on those boards.

 

 

 

 

 

 

Colin doing the hands-on demo, while projecting it through the ‘camera projector’ so audience didn’t have to gather around the table to see what he was doing.

 

 

 

 

 

 

Group paying attention to Colin.

 

We would love to host another session where childern can all potentially get hands-on experience building something.  Microsoft, please go ahead and release this really cool technology!!

King County Science Activities Club

November 4th, 2010

We are sponsoring a forum for community to suggest and participate in STEM related activities for themselves and/or their children. 

See more details at: http://www.meetup.com/cascadescience/ and join in for spreading the message of fun, hands-on science related events in King County, Washington.

Application of the ‘egg drop’

July 21st, 2010
Egg Drop at Medina

A student dropping an egg from the school balcony

After the completion of the ‘egg drop’ in 2009, Ellis Corets visited a 6th grade classroom in Medina Elementary School at the invitation of Kristi Stroyan, the school teacher and a board member of the Cascades Science Center Foundation, to discuss the egg drop event.   Ellis asked the students, if they could think of a real world application of the egg drop principle. 

Ellis then asked them if they were familiar with the recent landings of the rover vehicles on Mars by NASA.  Ellis described to them that there is little or no atmosphere on Mars, so a parachute cannot be used, as many students were using to drop their eggs from the balcony in the school.  

NASA’s approach was to place the rover vehicle in a tetrahedron - they called it “Spacecraft Lander”.  A tetrahedron is a four sided figure, each side being an equilateral triangle.  The tetrahedron was then wrapped in the equivalent bubble wrap.  This package was then dropped from orbit and landed on Mars. It bounced and bounced and bounced and rolled and finally came to a stop.  The protective wrap peeled off.  The tetrahedron opened.  And the rover drove off into the sunset.  Read more about the Spacecraft Lander on NASA website.

Why American students are lagging in math and science?

July 3rd, 2010

Good article that talks about why American students are lagging in math and science.

http://blog.openstudy.com/2010/04/06/why-american-students-are-lagging-in-math-and-science/

Science Camps in Washington

June 27th, 2010

At Cascades Science Center Foundation, we would like to get our organization established to a point where we can have capacity and capability to host hands-on science camps for kids in the summer.  We need resources!

Until we get there, here is a list of other organizations and institutions in Washington, hosting hands-on science-oriented events:

  • Bellevue College (August 16 – 20, 2010): The Summer Science Camp seeks to instill a sense of enthusiasm and inquisitiveness about science in fifth and sixth graders. We offer “hands-on, minds-on” experiences in a variety of scientific disciplines, including astronomy, biology, botany, chemistry, earth science, physics and more.
  • Champions Science Adventures: Each week long camp program is packed with fun experiments, individual projects and engaging science learning for kids ages 5-12.  Better yet, kids get to take home the amazing projects they build providing fun science-oriented play for years to come.
  • Mad Science: Mad Science® is the world’s leading science enrichment provider. They deliver unique, hands-on science experiences for children that are as entertaining as they are educational.

We wish you a very happy summer full of scientific discovery!