A. Place a plastic weighboat on the scale and tare (re-zero) the
scale.
B. Measure 1.0 g of the copper gluconate in the weighboat on
the scale. If you don’t land exactly on 1.0,
that’s OK. Just get as close as you can, and record the exact
mass in Table 1 below.
C. Transfer all of the copper gluconate into a glass 250 mL
beaker. Try not to leave any behind in the
weighboat, as this will affect your calculation later.
D. Using a clean, dry 10 mL graduated cylinder (you may want
to first rinse with distilled water prior
to using, then dry), measure 10.0 mL of 0.5% NaCl solution,
and pour it into the beaker with the copper
gluconate. If you need to use a pipette to help transfer the
NaCl into the graduated cylinder, that’s fine.
You may need to gently swirl or stir (with your glass
stirring rod) the solution if all the copper gluconate
does not immediately suspend into the solution.
E. Place 2 aluminum (Al) washers into the beaker with the
solution.
F. Fasten your iron ring to your ring stand, about 6-10
inches high. Place your beaker on the iron ring. It
should fit just enough inside the ring where it won’t fall,
but if yours does not fit as nicely as you’d like, you
can place your watchglass over the ring to create a more
stable platform on which to sit your beaker. Be
very careful that your beaker does not fall, or you will lose
your data for this experiment, not to mention
have a mess to clean up.
G. Place your Sterno® fuel underneath your beaker. This will
be your heat source and take the place of a
traditional Bunsen burner. Your final setup should look
similar to this:
Lab 3 Assignment
5/21/17, 9:23 AM
Lab 3 Assignment
Part 1 of 1 –
4.0 Points
Question 1 of 7
Using your own lab results, show your calculations for your
moles of copper produced. You must show all work to
receive credit.
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4.0 Points
Question 2 of 7
Using your own lab results, show your calculations for your
moles of gluconate. You must show all work to receive
credit.
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text editor): 60,000
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3.0 Points
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Page 1 of 3
Lab 3 Assignment
5/21/17, 9:23 AM
Question 3 of 7
Using your own lab results, determine the chemical formula of
copper gluconate. You must show all work (not just the
formula) to receive credit.
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2.0 Points
Question 4 of 7
List two sources of error in the experiment and explain the
impact they had on the results.
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3.0 Points
Question 5 of 7
Using your own lab results, calculate the percent composition
of copper and the percent composition of gluconate in
the compound copper gluconate. Clearly label each ion (copper
and gluconate) and the percentage. You must show all
work (not just the formula) to receive credit.
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Page 2 of 3
Lab 3 Assignment
5/21/17, 9:23 AM
4.0 Points
Question 6 of 7
Please upload (in PDF format) your experimental setup picture
as explained in Step 7 of the Lab 03 Document. This
must be a single picture PDF file.
NOTE: If your picture is not clear or any part of it cannot
be read by your instructor, you will not receive credit.
Click “Browse” to locate your file and then click “Upload” to
upload your file. (Maximum file size: 20MB)
File:
Choose File
no file selected
Upload
5.0 Points
Question 7 of 7
Please upload (in PDF format) your dried copper picture as
explained in Step 8 of the Lab 03 Document. This must be a
single picture PDF file.
NOTE: If your picture is not clear or any part of it cannot
be read by your instructor, you will not receive credit.
Click “Browse” to locate your file and then click “Upload” to
upload your file. (Maximum file size: 20MB)
File:
Save
Choose File
no file selected
Upload
Exit
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Page 3 of 3
Lab 3: Compound Formulas
Introduction
1. Open up your student lab manual (PDF) that came with your
kit. You can either access it from the DVD that
came inside your kit, or else download it from
www.esciencelabs.com (you will first have to register your kit,
which you should have already done by following the
directions in Lesson 1).
2. Access “Lab 4: Compound Formulas” in your student lab
manual (pp. 63 – 68), and read the sections titled
Introduction, Chemical Compounds, Percent Compositions, Molar
Concentration, Molar Ratios, and answer
the pre-lab questions (p. 63 – 65).
3. Visit www.esciencelabs.com, log in, and click on the
Student tab.
4. Under the heading “Kit Resources” on the eScience website,
click on General Chemistry Version 1 (or Version
3), and again on General Chemistry Version 1 (or Version 3)
on the next screen.
5. Click on the link “Matter and Structure,” then find and
watch the following slideshow animations and lab
drills (NOTE: For the slideshow, you will have to click on
the “Audio” button to hear the narration):
Concept Animation: Compound Formulas
Chemical Formulas
Lab Drill: Compound Formulas
Objective
To experimentally (i.e. not just look it up or use the naming
rules!) determine the chemical formula of copper
gluconate by chemically isolating the copper to determine the
mole ratio of copper to gluconate in the
compound.
Materials
Procedure
NOTE: Gluconate is a polyatomic ion, (C12H22O14-), so think
of this entire group of atoms as a single ion unit (in
other words, just like Cl in the example shown on p. 65 in
the eScience Lab Manual). Your task in this lab is to
determine how many moles of both copper ions and gluconate
ions are present in your sample, then set those
molar values as a ratio to one another to determine the
formula. For example, if at the end of your experiment
you calculate that you have x moles of copper, and y moles of
gluconate, then you write the formula as Cux
(C12H22O14)y, then follow the procedure as shown on p. 65 of
the lab manual.
6. Complete Experiment 1: Determining the Chemical Formula
for Copper Gluconate.
A. Place a plastic weighboat on the scale and tare (re-zero)
the scale.
B. Measure 1.0 g of the copper gluconate in the weighboat on
the scale. If you don’t land exactly on 1.0,
that’s OK. Just get as close as you can, and record the exact
mass in Table 1 below.
C. Transfer all of the copper gluconate into a glass 250 mL
beaker. Try not to leave any behind in the
weighboat, as this will affect your calculation later.
D. Using a clean, dry 10 mL graduated cylinder (you may want
to first rinse with distilled water prior
to using, then dry), measure 10.0 mL of 0.5% NaCl solution,
and pour it into the beaker with the copper
gluconate. If you need to use a pipette to help transfer the
NaCl into the graduated cylinder, that’s fine.
You may need to gently swirl or stir (with your glass
stirring rod) the solution if all the copper gluconate
does not immediately suspend into the solution.
E. Place 2 aluminum (Al) washers into the beaker with the
solution.
F. Fasten your iron ring to your ring stand, about 6-10
inches high. Place your beaker on the iron ring. It
should fit just enough inside the ring where it won’t fall,
but if yours does not fit as nicely as you’d like, you
can place your watchglass over the ring to create a more
stable platform on which to sit your beaker. Be
very careful that your beaker does not fall, or you will lose
your data for this experiment, not to mention
have a mess to clean up.
G. Place your Sterno® fuel underneath your beaker. This will
be your heat source and take the place of a
traditional Bunsen burner. Your final setup should look
similar to this:
H. (You will be taking a picture as part of this step—see
Step 7 below). Remove the inner cap on the Sterno®
and ignite the inner contents with the matches. Heat the
beaker until the solution clears. Your solution
may not turn completely clear, but some color change should
be evident. Alternatively you can also
determine when the reaction is complete by looking for the
formation of gas bubbles on the surface of the
washers. When the formed gas bubbles are gone, then the
reaction is complete. Make sure your washers
are completely submerged in solution. You may have to rock or
swirl or tilt the beaker during the reaction
to ensure this. But careful…the beaker will be HOT!
Note: Carefully monitor the set-up while the Sterno® is in
use. You may need to adjust the height of
he ring/beaker to ensure that the beaker is heated enough;
and, to avoid exposing the beaker from
high heat.
**Carefully observe the set-up you choose!! Do not leave the
beaker unattended while exposed to the
Sterno®. Plastic beakers should never be used with heat.**
I. When the reaction is complete, carefully remove the beaker
from heat, and use forceps to replace the lid
on the Sterno®. Carefully decant (pour off) the clear(ish)
liquid into a 50 mL beaker.
J. When all that remains in the original beaker are the
copper plated washers, rinse the washers with
distilled water (dH2O) and again decant the remaining liquid,
being careful not to lose any copper, into a
container. This water can be disposed of down a sink drain.
Repeat this rinsing process three times.
K. Place a metal cupcake wrapper on the scale and record its
mass in Table 1 below. Remove the wrapper
from the scale, and carefully remove the first washer and use
the stir stick to scrape the copper into the
metal cupcake wrapper.
L. Rinse the washer with just a little dH2O over the wrapper
just to be sure all copper is recovered into the
wrapper. Don’t worry, this water will evaporate away when you
dry the product (dessicate it) in the oven.
However, use as little dH2O as possible, since the more you
use, the longer it will take to dry.
M. Repeat the process for the second washer, scraping/washing
the copper into the same wrapper.
N. Place the wrapper on a baking pan and put it in the oven
at 115 °C (239 °F) to dry the product. Monitor
the wrapper and contents and use a hot pad or towel to
carefully remove them from the oven after 45
minutes, or after all of the water has evaporated.
O. (You will be taking a picture as part of this step—see
Step 8 below). After the wrapper has cooled to room
temperature, weigh the final mass of the wrapper with the
copper inside it. Record the mass in Table 1
below. Subtract this mass from the starting mass of copper
gluconate to determine how much gluconate
was in the original sample. Record this value in Table 1.
7. After completing the experimental setup and beginning the
experiment (Step 6-H above), make a label with
your name, the lab title, and the date, and place it next to
your experimental setup. Unless all three—your
name, the lab title, and the date are on the label and
legible, you will not receive credit. Take a picture of
each of your setup, and make sure your label can be read
clearly in your picture. Save this picture in a PDF
document in order to submit it in the Lab 3 Assignment.
8. Once your experiment is complete, take a picture of your
dried copper being weighed on the scale. The
copper and the mass value must both be visible in the
picture, as well as a label with your name, the lab title,
and the date. Unless all three—your name, the lab title, and
the date are on the label and legible, you will not
receive credit. Save this picture in a PDF document in order
to submit it in the Lab 3 Assignment.
9. Clean up your lab and put away your materials. Wash your
glassware (and plasticware) with warm water and
soap. To minimize spotting and mineral contamination, it is
best to do a final rinse with dH2O. Dry your
glassware (or leave set to dry) and put it away. All
chemicals used in this lab can be safely washed down the
sink.
Results
10. Make a data table in either Word or Excel that shows the
data necessary to determine the formula of your
compound. All work must be shown neatly and clearly as part
of your table. Your table should look something
like this:
Table 1: Copper Gluconate Formula Data
Mass (g) of copper Mass (g) of wrapper
gluconate
(Show all work to receive credit)
Moles of Cu recovered:
Moles of Gluconate:
Mass (g) of wrapper
+ Cu
Mass (g) of Cu
Mass (g) of gluconate
Experimental Chemical Formula:
11. You should have 2 PDF documents when finished with this
lab—1 for your experimental setup, and 1
containing your dried copper being weighed. All pictures and
labels must be clear or they will not receive
credit.
12. Answer the post-lab questions below.
13. Go back into the course classroom, click on Tests &
Quizzes located on the left side menu, and complete the
Lab 3 Assignment posted there. Remember, it is in a quiz
format, but it is not a quiz. You can access it as
many times as you wish while entering your answers, and it is
not timed. Just be sure that you do not actually
click “Submit” until you are ready to be graded.
NOTE: There is space provided in the student manual at the
end of each lab for you to write a lab report. You
will NOT be writing lab reports in this class. You are only
being graded according to the last step listed above.
Post-lab Questions
1. List two sources of error in the experiment and explain
the impact they had on the results.
2. Using your own lab results, calculate the percent
composition for each element in the compound copper
gluconate. Clearly label each element and the percentage. You
must show all work (not just the formula) to
receive credit.
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