Sample Lab Report
Note that all the numbers and measurements are fictional and do not represent an actual experiment. (This is only the example for you about how to write a lab report)
Title: Testing the Cohesive Nature of Water
Abstract
This experiment was done to test the surface tension and cohesion of water molecules.
Additional liquids were also tested to analyze properties which may affect the cohesive nature of a solution.
In order to do this, water was pipetted onto a penny in a drop-wise manner. The data was recorded
and analyzed and found that water molecules are very cohesive and exhibit a surface tension.
Introduction
Background: Cohesion describes the natural attraction exhibited by certain molecules. Water
molecules are polar molecules, and thus are attracted and bind to each other using hydrogen bonding.
Cohesive forces will become evident when the water droplets meet the edge of the penny. Surface tension
is used to quantify the cohesive forces.
Objective: This experiment will examine the cohesive nature of water molecules.
Hypothesis: The number of water droplets which can stick to the surface of a penny will exceed
the amount of droplets which can fit on the surface area of a penny
Materials and Methods
1 Penny
1 Pipette
1 Glass of Water
Fill a glass of water with a sample of room temperature water. Place a penny on a flat work
surface. Use
the pipette to slowly pipette water onto a penny one drop at a time. The number of drops was
counted
and recorded in a data table. Repeat this process four more times (for a total of five trials).
Record the average amount of water droplets which stuck to the penny over the five trials.
Results
Trial Number Number of Water Droplet
1 29
2 33
3 32
4 32
5 35
Average 32.2
Discussion
Assuming that a penny can fit approximately 10-15 drops of water (depending on the pipette
used), the hypothesis is proven to be true. The cohesive nature of water enabled the water molecules to
“stick” to each other when the edge of the penny was met. In this way, the water molecules were able to
cling to each other creating a vertical structure.
This study was only done with one water sample and one penny. To truly test this principle, additional
water samples from different sources should be tested. Further, different pennies should be used
to verify that there are no particles on the penny affecting the water cohesion. Other solutions (such
as acidic or basic solutions) could be evaluated to determine if other properties are affecting the
cohesion.
Conclusion
Water molecules are very cohesive and exhibit a surface tension. This enables the water
molecules to stick to each other in a vertical direction.
References
1. Laboratory Manual by Imaginary Science, Second edition, 2016.
2. https://water.usgs.gov/edu/adhesion.html
