Elizabeth Hopkins
CHM151
Class # 24521
Date: 10/21/2022
Lab 2: Density of a Solid Object
Purpose:
The purpose of this lab is to demonstrate understanding of scientific data based on scientific
measurements and to express this data in a scientific form. This lab involves finding the density
of a regular solid object by using two different methods to find the volume of the object. The
first method is measurement by a metric ruler and using the formulas: volume of a truncated
cone and density. The second method is using volume by displacement where placing an object
into water will displace and cause the level to rise. The change in level of the liquid will be equal
to the volume.
Materials:
1.
2.
3.
4.
5.
6.
Regular solid object (rubber stopper)
100 mL graduated cylinder
Metric Ruler
Water (Tap)
Calculator
Pencil and Paper
Procedure:
1. Gather materials needed that are required for this lab. Clean off area to make sure no
clutter to avoid any type of spills and ability to see measuring tools.
2. Remove the solid object (rubber stopper) from the lab kit and notate the weight in grams.
3. Using the metric ruler obtained from lab kit, measure the diameter of the two flat surfaces
on top and on the bottom of the rubber stopper. Follow this with measuring the height of
the rubber stopper and notating measurements on separate piece of paper.
4. Take the measurements written down and add them to the Excel spreadsheet under the
Ruler Method Data
5. Fill the 100 mL graduated cylinder to the desired amount using tap water and making
sure to read the measurement at the bottom of the meniscus (the lowest point on the
curved surface of the liquid.) Mark this as the Initial Volume (mL)
6. Place the rubber stopper into the 100 mL graduated cylinder and from there read the
bottom of the meniscus for the Final Volume (mL)
7. Enter in the calculations onto the Excel Spreadsheet in the correct areas for the Water
Displacement Data and the Ruler Method Data.
8. After entering the calculations, Water Displacement Calculations and Ruler Method
Calculations can be seen underneath the data as well as the percent area calculations.
9. Once done with this laboratory, clean up by draining out the tap water from the graduated
cylinder. Dry off the rubber stopper and place back into the container it came in. Even
though no hazardous chemical were, still wipe down area worked on.
10. Wash hands after cleaning down work area.
Elizabeth Hopkins
CHM151
Class # 24521
Date: 10/21/2022
Data:
Water Displacement Data
Ruler Method Data
Mass object (g)
8.14
Initial Volume (ml)
42.5
Final volume (ml)
48.5
Diameter 1 (cm)
Diameter 2 (cm)
Height object (cm)
Pi
1.84
1.58
2.66
3.141592654
Water Displacement Calculations
Ruler Method Calculations
Volume object (ml)
Radius 1
Radius 2
Volume object (cm3)
0.92
0.79
6.1
Density object (g/cm3)
1.33
Density object (g/ml)
Percent error
6.0
1.36
13.06
Percent error
10.83
Calculations:
1
Volume of a Truncated Cone Formula: 𝑉 = 3 𝜋(𝑟12 + 𝑟1 𝑟2 + 𝑟22 )ℎ
𝑀𝑎𝑠𝑠
Density Formula: 𝐷𝑒𝑛𝑠𝑖𝑡𝑦 = 𝑉𝑜𝑙𝑢𝑚𝑒
Water Displacement (Finding Volume of a Solid): (𝑉𝑓𝑖𝑛𝑎𝑙 − 𝑉𝑖𝑛𝑖𝑡𝑖𝑎𝑙 )
Percent Error:
[accepted value−experiemental value]
×
accepted value
100
Results:
The density of the rubber stopper was found to be 1.29 g/mL when using the Water Displacement Method
and 1.33 g/cm3 when using the Ruler Method Calculations. The accepted value for the density of the
rubber stopper is 1.20 g/cm3.
Elizabeth Hopkins
CHM151
Class # 24521
Date: 10/21/2022
Discussion Questions:
1. What was the percent error for each of the two methods for calculating the densities?
The percent error for the Water Displacement Method was 13.06% and the percent error for the Ruler
Method was 10.83%
2. Which method do you believe is more accurate?
I believe that the ruler method is more accurate. This is because the measurements are more precise
since we can estimate to the 0.01 cm instead of the 100 mL graduated cylinder which we can only estimate
to 0.1 mL. It is interesting to see how much of a difference there is between the two methods.
Conclusion:
This lab was to help to understand how we can calculate the density of an object by two methods
which are by water displacement for finding the volume of a solid and the ruler method by measuring the
object. The data that needed to be collected first included the mass of the rubber stopper, the length of the
diameter on the top and bottom of the rubber stopper, and the height. With this information, we can use the
formula to calculate the volume of the truncated cone. The water displacement method is using the 10 mL
graduated cylinder and we place the rubber stopper in the water to see a different way to calculate the
density of an object and includes taking the initial volume of the water in the cylinder and then the final
volume after the rubber stopper has been added into it. Subtracting the initial from the final volume of water
we then can use that volume number to then divide the mass of the rubber stopper to finally get the density
of the object by that method.
The results of my calculations show that the Ruler Method data being closer to the accepted value
of the rubber stopper which is 1.20 g/cm3. Since this accepted value is known, the error is expressed as a
percent error instead of a percent difference. The Ruler Method has a percent error 10.83%, which does not
seem to be as high. I believe the errors did come from me struggling with seeing the cm on the ruler that I
used. The percent error for the water displacement method has a percent error of 13.06%. I believe the same
error for calculating the measurements with me trying to determine where the uncertainty. I feel as though
the water displacement method should have been the best method, but the Ruler Method percent error
calculations were 2.23% smaller than the water displacement method.
This lab was quite fun, and it helped me gain more knowledge on the differences of using water
displacement versus the ruler method. It shows that even though the rubber stopper has an accepted value
that I still came up with different results. It really highlights just science is unique in that millions of people
around the world can each end up having different results in the end. This was also a great way to help me
with conversions for future use.
References:
Flowers, P., Theopold, K., Langley, R., & Robingson, W. R. (2019, February 14). 1.4 measurements chemistry 2E. OpenStax. Retrieved October 21, 2022, from https://openstax.org/books/chemistry2e/pages/1-4-measurements
Elizabeth Hopkins
CHM151
Class # 24521
Date: 10/21/2022