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Popcorn Lab

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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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