Chemistry Simulations vs Hands-On

Note: I'm hoping to post at least a couple more experiments here -- one that we are still trying to get to operate as advertise -- before turning our attention to biology for the coming school year. (I've just set up homebiology.blogspot.com in anticipation!)

But in the meantime I'd like to pass along an email my friend and fellow homeschooling parent Paul Fernhout sent our local homeschool email list today with some thoughts on chemistry simulations:

In regard to something else I am looking into, I found a website today I wanted to share by Professor William J. Vining at the State University of NY at Oneonta. He has helped develop free chemistry simulations that should run in most web browsers with a Shockwave/Flash plugin installed. At least most of the first five or ten simulations in the list at that URL should be easy enough to play with about some basic ideas of chemistry (the periodic table, etc.). I think the simulations all go with a specific text book, but the general concepts would apply for any person interested in chemistry even without a specific textbook. Essentially, these are all safe scientific toys which may (or may not) in turn inspire further interest in the topic of chemistry. So, think of most of them more as chemistry puzzles (what could they mean?) than chemistry instruction.

From Prof. Vining's main page:

My principal interest lies in developing and testing educational materials and methods for chemistry. The materials are primarily computer-based multimedia software systems that serve the dual purpose of simulating the exploratory nature of chemical investigation and also make use of graphical advantages of computer systems to better explain chemical concepts. The focus of these programs is to enable students of chemistry to explore chemical concepts in a manner that leads them to discover those concepts independently. Because chemical concepts are based on analysis of experimental results, the software systems we design are centered around presenting the student with information they would obtain from an experiment, along with computer-based tools for analyzing those results. This allows the student to observe trends and choose the appropriate experiment to answer a particular question. Once an area of chemistry has been presented by an interactive experimental simulation, the concept can then be explained using multimedia tools such as videos and animations. Our work involves preparation of materials appropriate for use in general, organic, inorganic, physical, and analytical chemistry. Recent projects have included work on a CD-ROM textbook for general chemistry and currently we are working on modules for organic chemistry.

He has some other resources linked from his main page, like some videos of mixing chemicals (though the one I tried did not play well for me). He also has some downloadable things (for Windows?) I did not try.

The Concord Consortium is another site with high quality free learning resources related to chemistry and other things as well, including for example CC Atoms. But some of these resources are harder things to try as they require Java and perhaps locally installing some things. Many (but not all) of these resources are designed for college courses, but could be fun to just play with for someone interested in chemistry who at least knew a bit to get
started with.

A chemistry simulation is definitely IMHO a good use of computers for older homeschoolers, since real (sometimes dangerous) chemistry sets are hard to get these days, making chemistry otherwise difficult to really explore in detail at home. There are some nostalgia and warnings there in the comments about old chemistry sets by the way (some had radioactive materials). There is a link in the comments to that blog post to a supposedly interesting set at Edmunds Scientific. But that set is $200 and obviously is going to take some supervision and pose some risks.

Scientific Explorer's Fizzy Foamy Science Kit of Safe Chemical Reactions is an example of a ($20) "safe" chemistry-related set we got for our child (age four) but it mostly just has stuff you'd find around the house like oil, baking soda, and vinegar (except maybe citric acid in pure form): "
A container of oil in it had leaked all over everything when we got it, but it cleaned up easily. It has some scientific looking stuff in it (not sure if it would be cheaper to buy it separately), but is probably not very interesting for older kids for that long.

The simulations let you try to do all sorts of things, although may be mainly of interest to older kids since they are more abstract (that is, no fizzing). Obviously, like all simulations, they are still not the same as the real thing, being worse in some ways and better than others. They will help kids get the intellectual challenge of chemistry, but they won't help them gain a sense of confidence in a lab setting they would get with the real stuff. But even if you had the real stuff, I'd suggest the simulations could still be interesting (perhaps even more interesting for a motivated learner).

Thanks, Paul!

Photosynthesis

I've been subbing in the public schools the last couple months (quite an experience after 10 years of homeschooling, but that's another story). Last week I had to go over plants with a class of third graders and then give them a test.

In the review materials, their teacher had given them the following formula:

CO2 + sunshine + water = food

This really made me nuts. When my kids were a little younger, I made it a point to find out just how plants turned sunshine into food. It took some doing, but I finally found a DK book that spelled out the relevant chemical formula. Which is this:

6CO₂ + 12H₂O + sunlight ---> 6O ₂ + C₆ H₁₂O ₆ + 6H₂ O
or...
carbon dioxide + water + sunlight --->
oxygen + carbohydrate + water

Now, she's already given them a chemical name (CO2 -- I asked and one child identified it as carbon dioxide). She could very easily have then given them H2O, water, and then done the math. The carbohydrate, glucose, is a form of sugar, which they would have readily understood -- especially here in upstate NY, where maple sugaring is common!

Actually, I was surprised to see "sunlight" in the actual formula; it provides the energy via chlorophyll, a green pigment that absorbs energy from sunlight. But most amazing of all --

THERE WAS NO MENTION OF CHLOROPHYLL!

(And photosynthesis was hand-written in on the test as an afterthought; I had to help the students out by letting them know that photo means light and synthesis is making something.)

Just to understand, as with most public-school science in my experience, the information the kids had to know was basically all vocabulary. For instance, they had to correctly label the cotyledon of a seed. Now, I doubt there are many adults who can identify cotyledon but not chlorophyll. Really.

Anyway, here, for the record, is my third-grader-friendly, chemistry-literate explanation of how plants make food. I am looking forward to exploring biology again (my plan for next year) in light of my ever-growing comfort with chemistry.

Radioactive Elements

I became interested in radioactive elements after my brush with thyroid medicine, and I started looking on eBay for a cheap Geiger counter. (My dad, who worked with X-ray machines, brought one home and demonstrated it for us when I was a kid -- another example of how early impressions about science can stick with you.) Before I could finish my research, a friend bought one for us. Turns out, what we actually have is a radiation detector intended for survivors of nuclear war. As one site I read said, if this thing shows a reading, evacuate!

So when I wanted to look at some common household radioactive items, we still didn't have anything to measure them with.

(This didn't work.)

So we found some nice videos on YouTube from people who did have real Geiger counters.

Among the radioactive items people collect or have about are:

smoke detectors (Americium)
salt substitute (potassium isotope)
Fiestaware dishes (the famous orange-y red made with uranium)
gas lantern mantles (a favorite of The Radioactive Boyscout)
old luminous watches (radium)

But here in Saratoga Springs, NY, we have one source of radioactivity that is less common: mineral water.

Back in the 1800s, Saratoga was known for its horse racing, its casinos, and its spas. Its many springs, the result of a geological fault which runs right through the center of the city (it's a low point known until recently as "The Gut", but now the source of trendy new restaurants). Apparently radioactivity is one requirement for "really good" mineral water.

The radioactivity comes from radon gas -- the same stuff that accumulates in basements, a by-product of the decay of uranium -- dissolving in the water underground. Once in the air, the radioactivity dissipates quickly, with a half-life of about four days.

Nevertheless, for the sake of science, we took a walk over to the Saratoga Spa State Park and collected a few bottles from the Polaris spring, one that is known to be radioactive. We also took a sip (it's carbonated but pretty sulfurous, so you wouldn't want to drink it regularly anyhow). So far, no one is glowing in the dark.

The radiation detector wasn't a total loss: it came with a really enlightening manual about radiation safety, for perusal in your fallout shelter. This article from the World Nuclear Association is also basic enough for kids. You'll also find all kinds of fascinating information about radiation at Theodore Gray's Periodic Table.

I'm still planning to get a working Geiger Counter, and maybe a few odds and ends from United Nuclear.

A word from our sponsor

A new chemistry post should be up this weekend, but in the meantime I'd just like to mention that I've just published my first book AROUND THE WORLD CRAFTS: Great Activities for Kids who Like History, Math, Art, Science and More!

The book is a collection of my Hands-on Learning columns from Home Education Magazine.

Enjoy!

Shrinky Dink polymers

I pulled out some sheets of shrink film lying around in my art cabinet so we could play with polymers. Polymers are long chains of molecules that can be manipulated in different ways. Shrinky Dink and similar thermoplastics are stretched using heat. When you re-heat them, they revert to their original shape. Here's a handout for kids from the American Chemical Society on making your own shrink film from recycled clamshell containers from the bakery or salad bar. Look for the #6 recycling symbol (other plastics will react in different ways in heat -- including by giving off toxic fumes). Number 6 is for polystyrene, the same stuff that Styrofoam is made out of. You obviously want the hard, thin, clear plastic, not the expanded puffy stuff.

It'd been a while since I played around with these, and I forgot that you have to let them curl up and then uncurl before removing them from the oven.

We popped them back in the oven and they straightened themselves out, with a little help where they had stuck together. Be careful fiddling around with them: when they're soft enough to unbend, they're still pretty hot.

Here's what the kids made:

Shrinkage: 60% (after baking twice)

Shrinkage: 50%

(By the way, it was a great day to be baking things, a brisk 50-something. In May. Helped me hold out against the urge to turn the heat on.)

Extra Oxygen

Lesson: The enzyme catalase splits hydrogen peroxide into water and oxygen.
What Happened: Adding yeast to hydrogen peroxide caused it to foam up with oxygen bubbles, which re-ignited an extinguished splint.

Science educator Robert Krampf has a collection of home science videos -- many but not all about chemistry -- on his website. He recently re-instated his email list, and I decided to try today's Experiment of the Day with some friends who are visiting. You can see Krampf explaining the experiment as he performs it on his website, which I have added to the sidebar. Here is an excerpt:

You will need:

1. a wooden, cooking skewer
2. a lighter
3. 3% hydrogen peroxide (from the grocery or pharmacy)
4. a cup or glass
5. yeast

Pour some hydrogen peroxide into the glass. Sprinkle some of the yeast into the peroxide and give it a stir. Very quickly you will see bubbles rising, producing foam on top of the liquid.

Light the end of the wooden skewer, and let it burn for a moment. Then blow out the flame. If you blow gently on the burning end, you should see a red glow. It is still burning, but not flaming. Carefully bring the glowing end of the skewer up to the larger bubbles in the foam. The skewer should flare up, bursting into flame.

We did not get the dramatic results that he gets in the video, but after a few tries we figured out that you need to let the skewer burn for few minutes to get hot enough to reignite.

Here is an explanation of how our bodies use catalase in the same way:

Hydrogen peroxide is a toxic by-product of respiration.  Organisms that
obtain energy by oxidation of foods must develop mechanisms to limit the
damage it causes.  This is primarily accomplished by a class of enzymes
called catalases, which catalyze the reaction

2 HOOH --> 2 H2O + O2

Surfaces and Density

This week we did a number of experiments with oil, water, food coloring and various props to explore the property of surfaces. The physical properties like surface tension and solubility are related to the strength of Intermolecular Forces -- the attractive forces between molecules.

Surface Tension Experiments

These came from the website of the Chicago Section of the American Chemical Society

3 bowls or containers with water
liquid soap
pepper
a piece of string
a paper clip
a fork
a needle

Bowl 1:

1. Sprinkle pepper on the surface of cold clean water in a shallow dish. Allow the particles to spread out and cover the surface.

2. Put your finger in the bowl.

3. Put a drop of liquid soap on your finger. Put your finger in the bowl again.

What should happen: Pepper should rush away from your finger in a star pattern.

What did happen: Pepper rushed away from finger in a circle -- still impressive.

Bowl 2:

1. Float a small loop of string in the middle of the surface of water.

2. Put a drop of liquid soap inside the loop.

What should happen: The surface tension inside the loop of string should weaken by the soap but the surface tension outside the string should have pulled the string outward.

What did happen: The string sank before we could try step 2.

Bowl 3:

1. Lower a paper clip and a needle flat onto the water surface using the fork. They should float.

2. If they don't, place a paper towel on the surface of the water, place the objects on the paper, and then remove the paper.

3. Now put a drop of liquid soap on the water surface.

What should happen: As soon as the tension is broken by the soap, these items should sink to the bottom.

This one worked as planned!

Density Column

Joy of Chemistry, page 131

2 clear glasses or plastic cups
Glycerin
Water
Food coloring
Cooking oil
Liquid soap
Plastic spoon

1. Pour about an inch of water into the cup.

2. Add food coloring to the water.

3. Pour about an inch of glycerin into the second cup.

4. Gently add colored water.

5. Add oil until you get three layers.

6. Stir. Allow to settle.The water will mix with the glycerin, but the oil will separate back out.

7. Add a layer of liquid soap.

8. Stir gently. The oil will mix with the glycerin.

What's Happening: Different liquids have different densities, and according to the density, the liquids will settle in a certain order when mixed. Oil is less dense than water and therefore will settle on top of water.

(NOTE: Glycerin--C₃H₅(OH)₃, which can be bought in drugstores -- can be added to dish soap to make long-lasting bubble solution. Bubbles eventually burst once the layer of water evaporates, but glycerin forms weak hydrogen bonds with water, delaying evaporation. )

Lava Lamp

(Sorry that it's sideways. When I figure out how to fix it, I will repost it!)

Tall narrow jar
Water
Food coloring
Vegetable oil
Salt

Directions:

1. Fill the cylinder with water.

2. Add the food coloring. Do not let the water become too dark.

3. Slowly pour oil into the cylinder. It should make a thick layer on top of the water.

4. Slowly sprinkle the salt into the cylinder on top of the oil. The salt coats the oil and causes it to fall to the bottom of the graduated cylinder in globs. The oil will gradually return to the top of the graduated cylinder.

What happened:

Vegetable oil is less dense than water. When the salt is added, it sticks to the oil and drags it down. Once at the bottom, the water dissolves the salt and the oil floats back up.

The reason the oil doesn't dissolve into the water happens because of its difference in polarity. Water and salt are both polar. Oil is non-polar. Only polar substances will dissolve polar substances. A non-polar substance will not dissolve in a polar substance. This is the rule of "like dissolves like."