 Your body needs minerals of many kinds for it to function properly. In particular, you need iron in your diet, because your body uses it to make haemoglobin, a chemical that uses iron to carry oxygen in the blood. To ensure that you get enough iron in your diet, tiny flakes of pure iron are added to many foods. Iron in its pure metal form is used because iron ions (which would chemically combine with substances already in the food) might cause the food to spoil. These flakes of iron metal are not microscopic in size; they're easily large enough to see with the naked eye. We'll show you how you can see the iron in your breakfast cereal! 
 You'll need some cereal, a few large sandwich bags, something to grind up the cereal with, a cup of hot water, and a strong magnet. First, grind up a handful of cereal thoroughly. We used a kitchen meat tenderizing mallet, but a rolling pin or even a blender would work as well. Make sure that most of the cereal ends up as a fine powder. Pour it into a plastic bag. Now pour a cup of hot water into the bag with the cereal. There should be more water than cereal; you want a bag of water with cereal in it, rather than a bag of wet cereal. When done, put the bag aside for 15 minutes or so. 
Next, lay the bag flat on a table and spread the wet cereal out as flat as possible. Place a sheet of white paper under the bag so the iron will be easily visible, once you collect it. Use the magnet to pull the iron flakes to one corner of the bag; run the magnet along the surface of the bag repeatedly, in the same direction. After a few minutes you'll notice little black specks appearing under the magnet. These are flakes of pure iron metal. The longer you rub the magnet over the bag, the more specks you'll see.  After you ingest the iron with the cereal, the hydrochloric acid in your stomach dissolves some of it so it can be absorbed by your digestive system. The rest is not used and gets excreted. |