2018 Clark Science Fair Procedure

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noted. This will help you see what to do and what not to do as you begin to write your procedure.
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Past Tense
Levels of IV tested
Personal Pronouns
Twenty milliliters of water were heated using a hot plate to a temperature of 38°C (approximately
100°F) and placed into a test tube. A 100mL graduated cylinder was held upside down and placed over the test
tube. The two were then held together in place and inverted as a unit (see diagram in Appendix A). The test
tube and graduated cylinder must fit snugly enough together so that the solution remains contained in the test
tube. After five minutes, observations were made and any change of water height was recorded. Next a packet
of Fleischmann’s active dry yeast was added into 100 mL of 38°C water. Ten grams of granulated table sugar
were then added to the solution and stirred gently for 60 seconds. A second test tube was filled with 10
milliliters of the yeast solution and 10 milliliters of water and inverted using a graduated cylinder as described
above. When exposed to the sugar and warm water, the yeast began a chemical reaction that released bubbles of
carbon dioxide gas. The amount of gas produced was determined by measuring the change in volume of the gas
bubble at the top of the inverted test tube.
This process was then repeated with the same yeast solution (warming the solution to 38°C each time to
simulate body temperature) in four additional test tubes. A 50% ethanol solution was provided by the adult
sponsor of this experiment and safety goggles, safety gloves, and a lab apron were worn when handling the
solution. Ethanol also releases harmful vapors, so the experiment was performed in a well-ventilated room with
windows open. 1.25 mL of this alcohol solution and 8.75 mL water were added to the 10 mL yeast solution in
test tube three, 2.5 mL alcohol and 7.5 mL water were added to the solution in test tube four, and 5 mL of
alcohol and 5 mL water were added to the solution in test tube five. In test tube six, 10 mL of the alcohol
solution was added directly to the yeast solution in the test tube. Mixing ingredients in this amount kept the total
amount of liquid in each test tube constant at 20 mL but still changed the percentage of ethanol in increments
from 0% to 35%. After inverting, each test tube was allowed to react for 5 minutes and then data and
observations were recorded.