Density of Rubber and Four Pure Metals
Introduction:
1) Density is an important feature of matter and is equal to its mass per unit volume. (d = m/V)
2) The SI unit for density is kg/m3.
a. This unit of measure is not practical so the conversion is made to g/cm3.
b. kg/m3 = (1
0
00g/1kg) x (1m)3/(10dm)3 x kg/m3 = g/cm3.
c. In addition, 1cm3 = 1mL, so density can be reported as g/mL.
3) This property of matter can help identify unknown substances.
a. If the mass and volume are measured, the density can be calculated.
4) Since density is characteristic of a substance, it can help assess purity.
a. The purity of a substance can be assessed by comparing the determined value to the actual value of density.
5) The density is a conversion factor between mass and volume.
6) Density is an intensive property of matter.
a. Intensive properties are independent of the amount of a substance.
b. Extensive properties depend on the amount of a substance such as mass, volume, and moles.
Substances to include in the Table of Chemical and Physical Properties:
The density of the following substances: zinc, copper, nickel, lead, polypropylene (rubber), water.
Procedure for Part 1: Density of Rubber Stoppers
1) Add 5
0.0
mL of distilled (or deionized) water to a 100.0 mL graduated cylinder.
a. Measure the exact volume of water added to the nearest tenth or first decimal place.
2) Place graduated cylinder onto a top-loading balance.
a. Once a stable mass is displayed, tare the balance (or set the mass to zero).
3) Obtain a combination of 5 rubber stoppers with sizes of 00, 0, 1, and/or 2.
4) Add one stopper at a time to the graduated cylinder and record the mass (or cumulative mass) of the stopper(s), the total volume to the nearest tenth, and the volume of water displaced.
a. Be careful not to splash out any of the water.
b. Record the mass indicated on the balance using all decimal places provided.
5) Continue to add rubber stoppers (without removing the previous ones) and record the cumulative masses, total volumes to the nearest tenth, and volumes of water displaced.
6) Graph the cumulative mass versus the cumulative volume displaced using a computerized graphing program.
a. The mass should go on the y–axis and the volume displaced should be placed on the x–axis.
b. Ensure that the plot has an appropriate title and both axes are labeled with the variables and units.
c. If using Microsoft Excel or a similar computerized program, ensure that all major and minor gridlines are turned on.
d. Have the program draw the best fit straight line using a linear regression.
i. Do NOT just connect all the points!
ii. Have the program report the equation for the line on the graph using the following generic formula: y = mx + b.
e. The density of the material is the slope of the line indicated by the coefficient of x.
i. If the equation is not available, to calculate the slope, choose two points that fall on the line and calculate the change in y over change in x via the formula: (y2 – y1)/ (x2 – x1).
Procedure for Part 2: Density of Four Pure Metals
1) Place
15.00
mL of distilled (or deionized) water into a 25.00 mL graduated cylinder (that is marked with 0.2 mL increments.)
a. Measure the exact volume of water added to the nearest hundredth or second decimal place.
2) Place graduated cylinder onto a balance.
a. Once a stable mass is displayed, tare the balance (or set to zero).
3) Carefully, place approximately 5 grams of the first metal into the graduated cylinder.
f. Record the mass (or cumulative mass) of the metal, the total volume to the nearest hundredth, and the volume of water displaced.
g. Be careful not to splash out any of the water.
4) Without removing the previous mass, add enough metal to bring the cumulative mass to
~10
grams.
a. Record the mass (or cumulative mass) of the metal, the total volume to the nearest hundredth, and the volume of water displaced.
b. If you overshoot the mass, do not remove anything from the graduated cylinder. Record the mass (or cumulative mass) of the metal, the total volume to the nearest hundredth, and the volume of water displaced.
5) Continue adding for mass amounts of
~12
grams,
~15
grams, and
~20
grams.
a. Record the cumulative mass of the metal, the total volume to the nearest hundredth, and the volume of water displaced.
b. If you overshoot the mass, do not remove anything from the graduated cylinder. Record the cumulative mass of the metal, the total volume to the nearest hundredth, and the volume of water displaced.
6) Repeat the above experiment with the other three metals.
a. The metals that you will use are: copper, lead, nickel, and zinc.
b. Be careful pouring out the lead; it is easy to spill.
7
) Graph the cumulative mass versus the cumulative volume displaced using a computerized graphing program.
a. The mass should go on the y–axis and the volume displaced should be placed on the x–axis.
b. Ensure that the plot has an appropriate title and both axes are labeled with the variables and units.
c. If using Microsoft Excel or a similar computerized program, ensure that all major and minor gridlines are turned on.
d. Have the program draw the best fit straight line using a linear regression.
i. Do NOT just connect all the points!
ii. Have the program report the equation for the line on the graph using the following generic formula: y = mx + b.
e. The density of the material is the slope of the line indicated by the coefficient of x.
i. If the equation is not available, to calculate the slope, choose two points that fall on the line and calculate the change in y over change in x via the formula: (y2 – y1)/ (x2 – x1).
c. Look up the true value for each metal and compare.
i. Using proper bibliographic technique, cite references for sources of true values.
Clean–Up:
1) Without allowing any of the metal fragments to fall into the drain, dispose of the water down the sink.
2) Dry off the metal fragments and place them in the labeled waste containers.
3) Stoppers should be dried off and returned to their storage bins.
Model Data Table:
Mass and Volume Measurements for Zinc Metal
|
Cumulative Mass of Metal (g) (y –axis on graph) |
Total Volume of Water (mL) |
Volume Displaced (mL) (x –axis on graph) |
||||
| 0 | 15.00 | |||||
|
5.2289 |
16.45 |
1.45 |
||||
|
10.1625 |
17.80 |
2.80 |
||||
|
12.9912 |
18.40 |
3.40 |
||||
|
14.8920 |
18.95 |
3.95 |
||||
|
21.2055 |
19.80 |
4.80 |
Draw the best fit straight line and the density will be the slope of the graph: Δy/Δx.
Data Tables:
Mass and Volume Measurements for Rubber Stoppers
|
Stopper Size(s) (00, 0, 1, or 2) |
Cumulative Mass of Stoppers (g) (y –axis on graph) |
Total Volume of Water (mL)* *to tenth place |
Volume Displaced (mL) (x –axis on graph) |
||||
|
0.00 |
0.0 | ||||||
Experimental/Observed Density for Rubber:
_________ g/mL
True/Theoretical Density for Rubber:
_________ g/mL
Percent Error for Rubber Density:
_________ %
Mass and Volume Measurements for Copper
|
Approximate Mass (g) |
Cumulative Mass of Metal (g) (y –axis on graph) |
Total Volume of Water (mL)* *to hundredth place |
||||||
|
0.0000 |
||||||||
|
~5 |
||||||||
| ~10 | ||||||||
| ~12 | ||||||||
| ~15 | ||||||||
| ~20 |
Experimental/Observed Density for Copper:
_________ g/mL
True/Theoretical Density for Copper:
_________ g/mL
Percent Error for Copper Density:
_________ %
Mass and Volume Measurements for Lead
|
Total Volume of Water (mL)* *to hundredth place |
Experimental/Observed Density for Lead:
_________ g/mL
True/Theoretical Density for Lead:
_________ g/mL
Percent Error for Lead Density:
_________ %
Mass and Volume Measurements for Nickel
Approximate Mass (g)
Cumulative Mass of Metal (g)
(y –axis on graph)
Total Volume of Water (mL)*
*to hundredth place
Volume Displaced (mL)
(x –axis on graph)
0
0.0000
0.00
~5
~10
~12
~15
~20
Experimental/Observed Density for Nickel:
_________ g/mL
True/Theoretical Density for Nickel:
_________ g/mL
Percent Error for Nickel Density:
_________ %
Mass and Volume Measurements for Zinc
Approximate Mass (g)
Cumulative Mass of Metal (g)
(y –axis on graph)
Total Volume of Water (mL)*
*to hundredth place
Volume Displaced (mL)
(x –axis on graph)
0
0.0000
0.00
~5
~10
~12
~15
~20
Experimental/Observed Density for Zinc:
_________ g/mL
True/Theoretical Density for Zinc:
_________ g/mL
Percent Error for Zinc Density:
_________ %
Banerjee
General Chemistry-I Lab
PAGE
7
General Chemistry – I
Banerjee
Banerjee
The lab notebook guidelines are included in this document.
1. Each lab period, in addition to coming to lab properly dressed, a pre-lab must be
prepared for the lab you are scheduled to perform that day. Failure to come to lab
without a complete pre-lab and improper dress will result in dismissal from the week’s
lab with a zero point allocation.
a. Each pre-lab should include the following sections: Name, Title, Date, Unknown,
Purpose, Balanced Equations, Table of Chemical and Physical Properties,
Procedure and an incomplete data table under Data Collected. This should be
uploaded on CANVAS before the start of lab and will be scanned for plagiarism.
This is due at the beginning of the lab period (mandatory).
2. Do not leave without checking out with your professor. You are allowed to use any
notebook or electronic notebook for this lab. Binded lab notebook is not needed for this
lab.
3. Lab reports (post-lab) are due 1 week following the completion of a lab. Each lab is
worth 100 points, comprising of pre and post lab. Your professor will provide further
instructions for completing your lab report.
a. Reports that are suspected to be plagiarized will be reported to the Dean, as
potential violators of the Academic Dishonesty guidelines (procedure 5026). This
will result in an F in the class. Self-plagiarism is also considered plagiarism.
4. The final lab report (post-lab) should comprise of 1) pre-lab sections, 2) Data collected,
3) Observations, 4) Discussion and 5) Conclusion and should be uploaded to CANVAS
placeholder.
Please upload at correct placeholder for each lab. Resubmissions are not allowed.
Please keep an eye on similarity score after submission.
Banerjee
Laboratory Notebook Guidelines
A proper laboratory notebook is one from which a given laboratory experiment can be repeated
by another chemist. Another chemist, chemical engineer or chemical patent lawyer should be
able to read your notebook and understand what you did and the results you obtained.
1. Every experiment should include the following sections listed below.
Title
Name
Date
Unknown (if any)
Purpose Describe the goal of the experiment.
Balanced Equation(s) (if any)
Table of Chemical and Physical Properties (including reference information, if
necessary)
Procedure & Do not provide a detailed, step-by-step procedure. The procedure is in
numerical form and should give the reader a general description of the procedure and any
special experimental details.
Observations . Throughout the lab, be sure to include any relevant observations: What
mass or volume did YOU use? Was the product a solid, liquid, gel, red precipitate, green
solution, etc?
Data Collected A sample data table is provided in each lab write-up. Record the
quantities of materials you used in the experiment. This includes calculations using
formulas, percent yield, percent error, etc.
Discussion Discussion should correlate expected data with obtained data in scientific
terms, without personal opinion.
Conclusion Conclusion should scientifically critic the success of the experiment, without
personal opinion and without over emphasis on errors.
The following sections must be completed prior to lab in the form of PRE-lab and uploaded to
CANVAS in correct placeholder: Name, Title, Date, Unknown, Purpose, Balanced Equations,
Table of Chemical and Physical Properties, Procedure and an incomplete data table under Data
Collected.
** All post-labs are due at the beginning of the next lab period on CANVAS, unless otherwise
specified. Each lab write-up is worth 100 points, including pre and post lab.
Banerjee
Lab reports must be written independently of lab partners,
students in other lab sections, and previous semesters’
students. Reports that are suspected to be plagiarized from any
of the previous sources will be submitted to the Dean, as
potential violators of the Academic Dishonesty guidelines
(procedure 5026). This will result in an F in the class.
THE FOLLOWING PAGE HAS A TEMPLATE ATTACHED FOR YOUR
CONVENIENCE:
Banerjee
Pre-lab
Your Name:
Title:
Date:
Unknown: (if none, write N/A)
(skip one line)
Purpose: Describe the goal of the experiment. Your purpose should answer the
following: What are you doing? Why are you doing it? How are you going do it?
This should be in your own words.
(skip one line)
Balanced Equations: (if none, write N/A)
(skip one line)
Table of Chemical and Physical Properties: The chemicals and
physical/chemical properties listed in the lab should be included in the table.
All the information can obtained from sigmaaldrich dot com.
Example:
Chemical
Name
Molecular
Weight
(g/mol)
Boiling
Point
(°C)
Density Safety
zinc 65.35 907 7.14
g/cm3
irritant,
combustible
copper
nickel
lead
polypropylene
water
Information obtained from:
http://www.sciencelab.com/msds.php?msdsId=9925476
http://pslc.ws/macrog/pp.htm
http://pslc.ws/macrog/pp.htm
Banerjee
Procedure
1. Obtain 50 mL H2O.
2. Tare graduated cylinder
on a balance.
3. Add a rubber stopper,
after recording size.
Observations:
Actual volume: xx mL
Color change:
Gas evolution:
Temperature change:
Data Collected: The provided data table can be pasted into this section or
rewritten for each lab. Include calculations for theoretical yield, actual yield,
percent yield, percent error, and any other calculations that were performed in the
completion of the data table.
(skip one line)
Discussion: Discussion should correlate expected data with obtained data in scientific terms,
without personal opinion.
Conclusion: Conclusion should scientifically critic the success of the experiment, without
personal opinion and without over emphasis on errors.
Contents of discussion and conclusion together should not exceed five scientifically written
sentences.
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