Saturday, January 24, 2009

science experiment How much iron is in your cereal?

This is from Robert krampf. I LOVE this blog! He has been doing it for a few years and if you ever have a rainy day, are in need of a cool science experiment, need an idea for a science fair, etc. This is the place to look. If you sign up for his blog (via Yahoogroups) you will get a weekly experiment emailed to you. You can visit his website for past experiments and some videos.

For this week's experiment, we are going to take some breakfast cereal apart, to see how they put in a full day's requirement of iron. To try this, you will need:

- some enriched breakfast cereal. Be sure it provides 100% of the daily

requirement for iron.

- a plastic bag that you can seal

- water

- a powerful magnet

- a sheet of white paper

Pour about a cup of the cereal into the plastic bag. Then add about a cup of water. Seal the bag and start squeezing the cereal, breaking it up into a mush. Keep squishing the mixture until most of the solid chunks have broken down.

Then place the magnet against the side of the bag. Slosh the contents back and forth across the magnet, making sure that the magnet stays in contact with the side of the bag.

After a few seconds of sloshing, lay the bag down on the white paper, and let most of the cereal mush run to the side of the bag away from the magnet. Slowly move the magnet, and watch closely. You should see tiny, black specks following the magnet. What is that? Iron.

What! There are chunks of metal in my cereal? There sure are. When they make the cereal, they mix powered iron in with the grains, sugar, and other ingredients. Don't worry. It's safe. Your body absorbs some of the iron, keeping you healthy.

Now, besides showing us that we are eating metal, this also demonstrates that breakfast cereal is a mixture, not a compound.

Mixtures are just what their name suggests, several different substances mixed together. If you put some salt and some sugar into a bowl, you have a mixture. They are mixed together, but not chemically combined, which means that you could separate them without having to chemically break them down. In the case of the salt and sugar, you could sit there with a magnifying glass and tweezers, as long as you had a LONG time.

Compounds are substances that have all their ingredients chemically bonded together into a single chemical formula. For example, during photosynthesis, plants combine carbon and water to produce sugar. Even with a very powerful microscope, and a wonderful pair of micro-tweezers, you could not pick out the bits of carbon and water from a bowl of sugar. They have been chemically combined into a single compound, with the formula C12H22O11.

Yes, you can separate the carbon and water by burning the sugar, but that is a chemical reaction. Mixtures can be separated without chemical changes, and that is what you are doing with the cereal. The iron is not chemically bonded to the wheat, sugar, marshmallows, raisins, chocolate chips, or the toy prizes found at the bottom of the box of cereal. Once you soften the cereal, and break it into small bits, the pieces of iron are freed to stick to the magnet.

Of course, you could use milk instead of water, which would make it a bit harder to see the iron, but you would have a nice snack when you are done.

Have a wonder-filled week.

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