Density of a Paper Clip Printer Friendly Version
 Purpose   To allow the student to become familiar with obtaining measurements with a triple beam balance and a graduated cylinder. Data analysis techniques are reinforced with the density being graphically calculated as the slope of the line Mass vs Volume.     Vocabulary   cubic centimeter density grams mass mean median meniscus milliliters mode volume

Beams

Use the "positions" of poises (counterweights) to calculate the "mass on the pan."  State your answers to 2 decimal places.
 A

 B

Record the volume of "water" present in each of the cylinders specified.  In each case, estimate your final significant digit.

 C

 D

 E

 F

 C D E F

Mass of a paper clip.

By using multiples of six (6) clips measure the mass of each collection of clips. Remember that each member of the group must measure each collection of clips. As a group you should reach a consensus to read each value to either one or two decimal places. Keep track of your significant digits and place units on every measurement! Be certain that you only use LARGE paper clips. A copy of this chart must be kept in your notebooks.

 Number of Clips Reader #1 Reader #2 Average Mass 6 12 18 24 30 36 42 48 54 60

Volume of a paper clip.

By using multiples of six (6) clips measure the volume of each collections of clips. Also, note that the all clips must be TOTALLY submerged before you read the volume of water. Since your graduated cylinders are marked off in 1 ml increments, you can only estimate one (1) decimal place. Remember that each member of the group must measure each collection of clips. Also, remember to keep track of your significant digits and to place units on every measurement!

Completely submerge 6 paper clips at a time in the water and record the new water level. Then, subtract the original water level from the new water level to determine the amount of water displaced by each cumulative collection of paper clips. After each group member has made his/her measurement, calculate the average change in water volume for each group of clips. ALERT: since 1 ml of water is displaced by each cm3 of solid paper clips, this average value needs to be expressed in cm3.

Original water levels: Start as close to 85.0 ml as possible; each person's starting point can be slightly different if necessary. Record all of your water levels readings for your graduated cylinder in the chart below.

 Number of Clips Reader #1 Reader #2 Average Volume of Clips original water _____ ml original water _____ ml new waterlevel net waterdisplaced new waterlevel net waterdisplaced 6 12 18 24 30 36 42 48 54 60

Graphical Analysis.

EXCEL will now graph your data. Minimize your browser, double click My Computer, double click the shared drive called colwell/bay on Lederman, double click your period's folder and then finally double click 1-density.xls. You will most likely be asked to open the file as "read only" - that is fine. As soon as the file is open, use File Save As to rename the file as

LastnameLastnameDensity.xls

in your period's folder. This copy of the file now belongs uniquely to your group. Remember that there are to be no spaces in the file name.

 What is the name of your density file?

Input your final AVERAGE values for Volume and Mass for each of the 10 collections of paper clips. As you enter your data, its graph will grow. Volume, measured in cm3 to 1 decimal place, will be placed on the x-axis and Mass, measured in grams to 2 decimal places, will be placed on the y-axis. When your graph is finished, be certain that any points that are obviously out-of-line have been rechecked for accuracy -- either in measurement, or for a mistake in typing.

Your graphs will be printed from my teacher station. Student stations do not have permissions to print to a local or network printer.

when you receive your printout, you are to write the equation of the line in the form "y = mx + b" along the graph's trend line. Be careful to use the correct "variables" -- M for "y" and V for "x" as well as the specific numerical values for your line's slope, "m," and y-axis intercept, "b." Since

M = DV

your group's experimental density is represented by the slope of your regression or trend line.

 What is the equation of your line?

Basic Statistics

When your group has calculated its value for the density of the paper clip material, go to the board and record your value so that the rest of the class can compare it with theirs.

Once again, minimize your browser, double click My Computer, double click the shared drive called colwell/bay on Lederman, double click your period's folder and then finally double click 1-densitystatistics.xls. You will most likely be asked to open the file as "read only" - that is fine. As soon as the file is open, use File Save As to rename the file as

LastnameLastnameDensityStatistics.xls

in your period's folder. This copy of the file now belongs uniquely to your group. Remember that there are to be no spaces in the file name.

 What is the name of your statistics file?

Your data is to be placed in column B on the sheet called RawData.

When all of the data has been recorded, we will rank them from smallest to largest and complete the statistics on median and mode.

Refer to the following information for the next three questions.

Individual Group Results
 Mode (most frequent value)

 Median (middle value)

 Mean (average value)

Standard Deviation

We will now use an EXCEL spreadsheet to calculate the variance and standard deviation for the density of a paper clip.

Click on the worksheet called Analysis. It will open with the format shown below. This spreadsheet has already been programmed to calculate the mean, (value-mean), (value-mean)2, variance and standard deviation. All you need to do initially is type in your group's information in cells E1-E8and the density values recorded on the board (or from your RawData worksheet) in column B.

The statistics quantity called the variance (s2) has already been programmed in cell B96. Its formula is

The standard deviation for the data has already been programmed in cell B97. Its formula is

After you have entered all of the data in ascending order, you will need to enter the total number of datapoints in B93. We will then record the values for the median in E15 and the mode in E18. When the spreadsheet is completed, resave your file

 Conclusion   Copy the following diagram on the bottom of your printout of Mass vs Volume. Place your group's value in its correct position on your diagram and write a conclusion stating where your group's result fell along this number line.     My group's density of _____ g/cm3 fell within ________ standard deviation(s) of the mean.

Lab Report

When finished, this lab report should include: a title page, Data Charts I, II, and the EXCEL graph of Mass vs Volume with your conclusion.

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