Penny Lab

Penny Lab Purpose: To determine how many drops of water fit on one side of a penny. Hypothesis: If the liquid placed on the penny decreases the surface cohesion, then the penny will hold less drops of water because the ingredients of the two liquids will mix adding mass, and the water will lessen the thick texture of the soap. Materials: (List all the materials used in the experiment)  100mL Glass Beaker  50mL Glass Beaker  Dropper  Forceps  Paper Towels Procedure: Part A: Perform a CONTROL test for comparison with later results. Step 1: Rinse a penny in tap water and dry completely. Step 2: Place the penny on paper towel. Step 3: Use an eye dropper to place drops of WATER on the penny (one at a time) until ANY amount of water runs over the edge of the penny. Step 4: Record the number of drops for that trial in the table. Repeat Steps 1 - 4 three more times before calculating your average. Number of drops TRIAL 1 Number of drops TRIAL 2 Number of drops TRIAL 3 Number of drops TRIAL 4 AVERAGE Number of drops 20 - Jared 13 – Ben 14 – Jon 9 – Kai 14 Part B: Perform tests with the TESTING LIQUID. Step 1: Start with a “clean” penny. Rinse the penny in tap water and dry completely. Be sure to remove as much residue as possible - without using soap! Step 2: Hold the penny with the tweezers provided, then dip it into the TESTING LIQUID. Allow extra liquid to drip off the penny into the container before proceeding to the next step. Step 3: Place penny on dry spot on a paper towel. Place drops of WATER on the penny (one at a time) until ANY amount of water runs over the edge of the penny. Step 4: Record your observations and the number of drops for that trial in the table. Repeat Steps 1 - 4 three more times before calculating the average. TRIAL 1 6 - Jared TRIAL 2 TRIAL 3 TRIAL 4 AVERAGE 5 - Ben 6 - Jon 1 - Kai 5 Observations: Part One: Labelled Diagram of Part Two: Labelled Diagram of observations: observations: Description: Description: -First experiment with water and penny. -Second test with soap -Highest amount of water drops: 20 -Thicker substance -Achieved better results than with soap -Added a slippery element, when mixed with -Water had stronger cohesive properties water is was slippery and became thinner, making it run off of the surface area of the penny. -Not as strong cohesive properties when mixed with soap solution. Results: Group One 20 Average Number of Drops on the Penny submersed in the soap solution 9 Group Two 25 8 Group Three 26 8 Group Four 23 7 Group Five 22 9 Group Six 14 5 Class Average: 22 8 Group # Average Number of water Drops on the Control Penny Conclusion: This experiment investigated the amount of water (drops) that could be fit within the surface area of a penny before it started to leak over the sides of the object. In order to study the problem, we needed to know the basics about water, it’s surface tension, and cohesive properties, to come up with a reasonable hypothesis and have the information to back it up. Results showed that after two series of testing, one with a dry penny and one with it being covered in dish soap solution. The first test proved to be more effective, and could fit more drops of water, than when it was covered in soap. This proved that the hypothesis that if the dish soap was added to the penny then acted as an independent variable in the experiment and was (supported/ negated) because it added a foreign element in the cohesive properties of the water, varying it’s results during the experiment. To extend this experiment, maybe explore other options as testing variables, such as other liquids to drop or use as a cover for the penny and see how the results differ. Or go more in depth around researching the exact reason why the results were the way they were. Finally, if the experiment was repeated, some changes to improve the experimental design could be ensuring a more controlled environment, with no possibility of disruptions or interference, for example, bumping the table, having an already wet penny, etc…