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Popcorn Lab Popcorn Through History The oldest ears of popcorn ever found were discovered in the Bat Cave of west central New Mexico. Ranging from smaller than a penny to about 2 inches, the oldest Bat Cave ears are about 4,000 ________years old. Popcorn Through History Biblical accounts of "corn" stored in the pyramids of Egypt are misunderstood. The "corn" from the bible was probably barley. The mistake comes from a changed use of the word "corn," which used to signify the most-used grain of a specific place. Popcorn Through History In England, "corn" was ______, and in Scotland and wheat Ireland the word referred to ______. Since maize was oats the common American "corn," it took that name -- and keeps it today. Popcorn Through History During the Great Depression, popcorn at 5 or 10 cents a bag was one of the few luxuries down-and-out families could afford. While other businesses failed, the popcorn business thrived. Popcorn Through History An 80,000-year-old fossil pollen found 200 feet below Mexico City has been identified as corn pollen. Popcorn Through History In tombs on the east coast of Peru, researchers uncovered 1,000-year-old grains of popcorn so well preserved they still pop. Popcorn Through History Microwave popcorn - the very first use of microwave heating in the 1940s – currently accounts for well over $200 million in annual U.S. sales Popcorn Through History Americans today consume 17 billion quarts of popped popcorn each year. The average American eats about 54 quarts ___________ Healthy Choice? Popcorn, Air Popped with no additives: Nutritional value per 100 g (3.5 oz) Energy 1,598 kJ (382 kcal) Carbohydrates 78 g Dietary fiber 15 g Fat 4g Protein 12 g Thiamine (Vit. B1) 0.2 mg (15%) Riboflavin (Vit. B2) 0.3 mg (20%) Iron 2.7 mg (22%) Percentages are relative to US recommendations for adults. Source: USDA Nutrient database Purpose: Determination of the amount of water in a popcorn kernel, and the pressure of the water vapor when the kernel pops Safety Issues 1. Heat the flask evenly to prevent spattering of oil 2. Heat carefully – oil is flammable. Make sure flask is securely clamped before igniting the burner. 3. Do NOT eat the popcorn – Sorry! Materials 1. Bunsen burner 2. Wire gauze 3. 125 mL Erlynmeyer Flask 4. Popcorn, oil and dropper 5. 10 mL graduated cylinder 6. Ring stand and ring 7. Utility clamp Procedures Mass the unpopped popcorn: 1. Mass 125 mL Erlenmeyer flask 2. Add 16 kernels to the Erlenmeyer flask and mass again. • Do the math =) Procedures Find the volume of the popcorn 3. Use water displacement method and a 10-mL graduated cylinder to determine the volume of the 16 kernels. (Hint: start with 5.00 ml of water.) Procedures 4. Add 2 drops of cooking oil and the 16 kernels to the empty, dry flask. Note: make sure the flask is dry first. 5. Determine the mass of the oil, kernels and flask Procedures 6. Cover the flask with holy aluminum foil – make the holes to let the water vapor out, but keep the popcorn in. Procedures 7. Place wire gauze on ring. Set the flask on top of the gauze, and use the clamp to secure the flask. Procedures 8. Light the burner. Use a small flame. Make sure it’s secured BEFORE starting the burner. 9. Carefully move the flame back and forth across the gauze to ensure even heating. Procedures 10* If you see water vapor condense on the side of the flask, move the burner to heat that side to drive off the condensation. Procedures 11. Remove the heat when most of the kernels have popped. Do not burn the popcorn. (If you burn the popcorn, you will need to start over.) Procedures 12. Let the flask cool. Determine the mass of the flask and contents. 13. Use a scrub brush to clean the flask with dish soap and water. Lab Calculations (show work) 1. Mass of unpopped kernels. 2. Mass of popped kernels. 3. Average volume of one popcorn kernel in mL and in L. Lab Calculations (show work) 4. Mass of water per kernel. 5. Moles of water per kernel. 6. % of water in popcorn kernel. 7. Pressure of steam inside the kernel at time of pop (b.p. for oil is approximately 225oC). Post Lab Questions 1. Did you expect the mass of popcorn to increase or decrease after it has popped? Why? 2. What is the purpose of the cooking oil? Questions 3. Compare the pressure required to “pop” corn to atmospheric pressure. Does that seem high? 4. What assumptions have you made that might cause errors in your calculation of pressure?
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