Scientist Guide. Nails for Breakfast? Introduction. Activity Overview. Materials

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1 Scientist Guide Nails for Breakfast? Introduction The periodic table of elements contains many elements that are essential for life, including oxygen, carbon and nitrogen. But did you know that iron (Fe) is also essential for life? Iron is an essential nutrient for both plants and animals. In plants, it is required for life-sustaining processes from respiration to photosynthesis. Insufficient iron uptake leads to Iron deficiency symptoms such as yellowing in leaves and reduction of crop yields. Plants need to maintain a specific concentration of iron to achieve optimal growth; however, they have a difficult time acquiring iron from the soil. Although iron is the fourth most abundant element in the Earth s crust, it is not readily available to plants. Thus, iron deficiency often limits plant growth, causing agricultural problems. In fact, one-third of the world s cultivated soils are considered iron deficient. Why do we need iron? In humans, a diet without enough iron can lead to iron deficiency, one of the most common of the nutritional deficiencies. Iron is present in all cells in the human body and has several vital functions. It is found in a part of our blood called hemoglobin, which helps our blood to carry oxygen molecules from our lungs to the rest of our bodies; it is used to produce energy in cells; and it is necessary for chemical reactions in various tissues. Too little iron can interfere with these vital functions. Our bodies can t produce iron, but it s naturally present in many foods, including meats (beef, pork, turkey), produce (spinach, raisins, prunes) and nuts (pecans, walnuts, peanuts), which are all agricultural products. The daily recommended allowance for iron is 18 mg (a 2-inch nail weighs approximately 2.5 g). Because some people don t get enough natural iron in their diets, iron is often added to foods like cereal. These foods are usually marked iron fortified. Small pieces of iron are added to fortified cereal along with the rest of the ingredients, and the iron added to your cereal is the same iron that is used to make nails! Activity Overview In this activity you will use iron s magnetic property to extract and quantify iron from three unknown cereals. Using the data you collect and the food nutrition labels of each cereal, you then determine the identity of each cereal. Materials Frosted Flakes, Total and Wheaties (30 g) Neodymium magnet Measuring cup Plastic plate

2 1 quart-sized Ziploc bag Water (H 2 O, distilled) Acetone (50 ml) Wash bottle with distilled water Balance (mg) Beakers (250 and 400 ml) Graduated cylinder Magnetic stir bar Magnetic stirrer Mortar and pestle Weighing dish Safety Precautions Avoid contact of all chemicals with eyes and skin. Wear safety glasses, lab coat and gloves when performing the experiment. Do not eat, drink or chew gum while in the laboratory. Acetone is a flammable liquid and a dangerous fire risk. Keep away from flames and other sources of ignition. Do not taste or ingest any materials in the laboratory. Once a food-grade item is introduced into a laboratory, it should be considered a chemical. Use caution when handling the super magnets; they can pinch the skin, erase credit cards and damage electronics. Wash hands thoroughly with soap and water before leaving the laboratory. Procedure Step 1: Skating cereal flakes. Using a graduated cylinder, measure 25 ml of water and add it to a plastic plate. Float one to three small cereal flakes (roughly the size of a dime) on top of the water. Place the magnet above the flake and, without touching the flake, try to move it around the surface of the water. Using the magnet, you may also try spinning the flake on the surface of the water. Observe how the flake is attracted to the magnet. Is there really metallic iron in your cereal? Proceed to the next step to find out. Step 2: Visualizing iron. Measure 1 cup of cereal and pour it into your plastic bag. Fill the bag one-half full with warm water and carefully seal it, leaving an air pocket inside. Gently knead the bag of cereal for a few minutes to break the flakes down. This process mimics the mechanical force generated during chewing. Allow the mixture to sit for at least 20 minutes so that the cereal begins to dissolve in the water.

3 Make sure the bag is tightly sealed and position it so it lays flat in the palm of your hand. Place the magnet on top of the bag and, using your other hand, flip the bag over so the magnet is now on the bottom. Gently swirl the bag for seconds. Using both hands, flip the bag over so the magnet is on top. Gently squeeze the bag to raise the magnet a little above the cereal soup. Look closely at the edges of the magnet. You should be able to see tiny black specks on the inside of the bag. That is iron! Keep one end of the magnet touching the bag and move it in circles. As you do, the iron will gather into a larger clump that should be easier to see. Few people have ever noticed iron in their food! Step 3: Quantifying iron. Weigh out 30 grams of cereal A, B or C, and grind the cereal into a powder using a mortar and pestle. Transfer the cereal to a 400 ml beaker and add 200 ml of warm tap water. Measure and record the mass of the magnetic stir bar and then gently place it in the beaker containing the cereal mixture. Place the beaker on a magnetic stirrer and stir the cereal for 30 minutes. While wearing gloves, remove the stir bar by grasping it in the middle in order to avoid dislodging the iron adhering to the stir bar. Using your water bottle, gently rinse the stir bar with water. Quickly dip your stir bar into 50 ml of acetone in a 250 ml beaker. Remove the stir bar and allow it to air dry in the vent hood. Weigh the stir bar containing the metallic iron and record your result. Calculate the mass of iron extracted from the cereal. Using the nutrition labels provided, determine which cereal was Total, Wheaties or Frosted Flakes. Compare the amount of iron obtained with the information provided on the Nutrition Facts label of the cereal. Did you extract all of the iron from the cereal? The iron filings may be removed from the stir bar as follows: Hold a mega-magnet in one place under a weighing dish. Bring the stir bar from above over the top of the weighing dish. The iron will drop into the weighing dish as it is attracted to the mega-magnet. Remove the mega-magnet vertically straight down under the weighing dish. Note: If the mega-magnet is removed to the side of the weighing dish, the iron will literally fly through the air to the magnet.

4 Try-on-your-own Activities Try this activity at home or in the classroom to learn about the chemistry of rust. Iron Burns Slowly, The Chemistry of Rust: Place a pad of steel (iron) wool into a jar. Pour in water to wet the steel wool and then pour out the water until only a small amount remains. Water helps the reaction go faster. Cut off the neck of a balloon and stretch a balloon across the mouth of the jar. Use a rubber band to fasten the balloon to the jar. Keep an eye on the jar; in a few hours, the balloon will begin to bend inward. Allow the jar to sit overnight and observe the balloon the next morning. It should have been sucked into the jar. Orange-red rust will begin to collect on the steel wool and will fall and settle to the bottom of the jar.

5 Scientific Data Sheet Nails for Breakfast? Sample Milligrams (mg) Initial Mass of Magnetic Stir Bar Mass of Magnetic Stir Bar With Iron Filings Mass of Iron Filings for Sample A Mass of Iron Filings for Sample B Mass of Iron Filings for Sample C

6 Scientific Data Sheet Nails for Breakfast? Using the nutrition facts labels below and your data, predict which cereal tested (A, B or C) was Total, Wheaties or Frosted Flakes. Total Wheaties Frosted Flakes Sample A: Sample B: Sample C:

7 Student Worksheet Nails for Breakfast? Name 1. What nutrient is essential for life Oxygen Carbon Iron All of the above 2. What element is the fourth most abundant in the earth s crust? Neodymium Phosphorus Beryllium Iron 3. Iron helps bind what molecule to hemoglobin? Nitrogen Oxygen Carbon dioxide Glucose 4. In a healthy diet, how many milligrams of iron a day is required for the average person? 18 mg 18 g 18 kg 18 ug 5. How much of the world s cultivated soils are considered iron deficient? One-half One-third One-quarter None of the above

8 Teacher Resource Nails for Breakfast? Follow-up Name 1. Most breakfast cereals are fortified with what mineral supplement? 2. What happens to plants if they do not get enough iron? 3. Iron is found in the center of what very important component of red blood cells? 4. What condition can result from not having enough iron in your diet? 5. True or False: Plants have a difficult time taking up iron from the soil?

9 Careers in Agriculture