Experiment #3a Aluminum Content via REDOX Reaction Ob.docx

Experiment #3a: Aluminum Content via REDOX
Reaction
Objective
To determine the aluminum content in commercial samples
through stoichiometry and a standard curve of the volume of
hydrogen gas produced versus the mass of aluminum consumed.
Introduction
Stoichiometry
Reaction stoichiometry is the numerical relationships between
chemical amounts in a balanced chemical equation. Using
stoichiometry allows us to predict the amounts of products that
will form or amounts of reactants that will be consumed
during a chemical reaction. In order to use stoichiometry to
predict such amounts, the chemical equation must be balanced.
As an example, let’s look at the following chemical equation:
� + → �2�3

It should be fairly obvious that the above equation is NOT
balanced. In order to balance this equation, we need to look at
the relative numbers of substances (A & B) on both sides of the
equation. On the left hand side (reactants side), we have
one A and one B. On the right hand side (products side), we
have two A (from A2) and three B (from B3). We must have
equal relative amounts on both sides. This one is rather simple
to solve. Using coefficients (NOT subscripts), we can produce:
2� + 3 → �2�3
This equation is now balanced.
Balanced equations can be used to calculate the amount of
reactants used or the amount of products formed in
a chemical reaction. For example, using the balanced reaction
below,
�2�4 + 3�2 → 2��2 + 2�2�
the amount of CO2 produced can be calculated when 40.0 grams
of C2H4 is reacted with excess O2 (excess means
that there is more than enough O2 for the reaction to go to
completion). For such a calculation, we can use the
following general process:

The first step is to convert 40.0 grams of C2H4 into moles of
C2H4 using the molar mass (28.05 g/mol). This can be
grams C2H4 moles C2H4 moles CO2 grams CO2
done using the factor-label method:
40.0 � �2�4 ×
1 �� 2�4
28.05 � �2�4
= 1.43 �� 2�4
Next, using the balanced chemical equation, determine the
number of moles of CO2 produced when
1.43 moles of C2H4 are consumed:
1.426 �� 2�4 ×
2 �� 2
1 �� 2�4
= 2.86 �� 2
The last step is to convert 2.86 moles of CO2 into grams of CO2
using the molar mass (44.01 g/mol):
2.86 �� 2 ×

44.01 � ��2
1 �� 2
= 125.9 � ��2
Alternatively, the entire process can be done at one time:
40.0 � �2�4 ×
1 �� 2�4
28.05 � �2�4
×
2 �� 2
1 �� 2�4
×
44.01 � ��2
1 �� 2
= 125.9 � ��2
This process can also be used in conjunction with the ideal gas
law to convert from volume of gas of one of the products
into the amount of mass of the reactant needed. For example,
the mass of C2H4 used to form 2.00 L of CO2 can be
determined at a pressure of 1.00 atm and a temperature of 293
K. First, the number of moles of CO2 must be calculated
from the ideal gas law:
� =
��

��
Where P is the pressure (in atm), V is the volume (in L), T is
the temperature (in K), and R = 0.08206 LatmK-1mol-1.
Substituting into this equation gives:
� =
(1.00 ��)(2.00 �)
(0.08206 Latm�−1��−1)(293 �)
= 0.0832 �� 2
From this, the mass of C2H4 used can be calculated using
stoichiometry and the molar mass of 28.06 g/mol:
0.0832 �� 2 ×
1 �� 2�4
2 �� 2
×
28.06 � �2�4
1 �� 2�4
= 1.17 � �2�4
Experimental Procedure

This experiment will be performed in groups of 3-4. Each team
will be using pure aluminum metal and two
commercial samples of aluminum foil and will set up a
Hydrogen Collection Apparatus, as shown in Figures
1 and 2. Your instructor will prepare a setup ahead of time to
serve as a reference.
Figure 1: Hydrogen Collection Apparatus Figure 2:
Hydrogen Collection Apparatus
Part I: Measurement of Hydrogen Gas
Assemble the apparatus shown in Figure 1 at one of the lab
sinks.
First, make sure that the tub is filled with water, Figures 2.
Obtain and completely fill a large graduated
cylinder (250-mL) with water from the tub. Carefully invert the
graduated cylinder, submerge it inside the
plastic tub in the sink and make sure that no air is trapped at the
top of the graduated cylinder. Make sure
that you do not raise the graduated cylinder above the water
level in the tub, or else you will need to start
over.

Connect the tubing to the filter flask, and insert the open end
into the mouth of the graduated cylinder
(while under water). Obtain a stir bar and stir plate. Place the
stir bar inside the filter flask. Place the
filter flask on top of the stir plate. Obtain a piece of pure
aluminum wire. Make sure to clean the wire
using steel wool. Add the sample of metal to the filter flask and
record the mass in your notebook.
Using the provided syringe, add 25mL of 8M hydrochloric acid
to the filter flask. Turn the stir plate on
and allow the reaction to stir until no more gas is evolved
(evidenced by consumption of the metal in
the filter flask). Read and record the volume of hydrogen gas
produced from the graduated cylinder in a
table in your notebook. Repeat this with three additional sizes
of aluminum. You may need to cut one
of the longer pieces of aluminum.
Mass of Metal Volume of Hydrogen
Pure

Aluminum
1
2
3
4
Repeat the procedure using Reynolds Wrap aluminum foil and
Great Value aluminum foil. Only perform
one trial with 50-110 milligrams of each type of aluminum foil.
Make sure to clean both sides of the
aluminum foil using steel wool. This removes the lacquer on the
foil, speeding up the dissolving process
and giving a more accurate starting weight. Read and record the
volume of hydrogen gas produced in a
table in your notebook.
Mass of Metal Volume of Hydrogen
Reynolds Wrap
Great Value

Part II: Data Analysis
With the data obtained, construct a standard curve using the
data you obtained for the pure
aluminum metal. Plot the volume (mL) of gas produced versus
the mass (g) of pure aluminum metal
consumed. Obtain the equation of the line and the R2 value.
Using the equation of the line, determine
the actual mass of aluminum metal present in both Reynolds
Wrap and Great Value aluminum foil.
Assuming the pressure in the laboratory is 1.00 atm and the
temperature is 293 K, calculate the mass
of aluminum in the aluminum foils using the ideal gas law and
stoichiometry.
11/6/22, 10:36 PM Upload Assignment: Week 5 Assignment -
Management Liability ...
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ASSIGNMENT INFORMATION
Mowers, Inc., a fictional company, has a flourishing lawncare
business. The business has two full-time employees who have
been with the company for five years.
All employees are trained on using the lawn equipment and,
upon being hired, signed a waiver-of-liability contract limiting
liability for the company.
The owner, Brian, tells his employees "Not to worry—the
company will protect you!”
One employee, Lori, was on the job cutting a lawn.
Lori was riding a mower, a Ferrari 2000, which was three years
old and in good working condition.
The step-up on the mower had writing on it with a warning
sticker to replace the sandpaper liner for traction every three
years due to normal wear and tear.
It was replaced every three years as required.
Lori stepped down off the rider, slipped because of moisture
from the grass, and severed her pinky toe on the mower blade.
When she fell to the ground, the mower continued through the
grass and proceeded by itself to cut and mulch a neighbor's
prize

roses.
Peta, the neighbor, was preparing for a rose competition with a
potential grand prize of $10,000.
Week 5 Assignment - Management Liability Scenario
Overview - In this assignment you apply contract and product
liability
law to a business scenario.
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Is there a “Design defect?” (Be sure to define these terms and
explain them)
Is there a “Manufacturing defect?”
Is there a “Failure-to-warn defect?”
3–4 pages, double-spaced, Times New Roman font (size 12), 1-
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Include at least three (3) quality references. The textbook for
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Include a cover page containing the title of the assignment, the
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Consider the above scenario and write 3–4 pages in which you
make
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QUESTIONS OF THE ASSIGNMENT:
1. Pursuant to contract law requirements, determine the legality
of the
waiver contract and whether verbal assurances become part of
the
written contract. Support your response.
2. Determine whether the plaintiff Peta has a product liability
case against the manufacturer Ferrari for each of the following
defects. Support your response.
3. Determine whether the employee Lori has a claim for injuries
and

whether the employee Lori can recover pain and suffering
damages per tort law or worker’s compensation law. Support
your
response.
Note:
Remember, you are demonstrating your understanding of the
law, so
explain the law first and then make your determination. Be
informative and show what you know! References should be
from
credible and reputable legal sources.
Formatting Requirements
Resources
Use the Strayer Library to conduct your research.
In addition to your textbook, you have access to Nexus Uni
through
the Strayer Library. You are encouraged to use the Strayer
Library to
conduct your research. The textbook for this class is a required
source
for this assignment.
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Experiment #3b: Aluminum Content via
Colorimetry
Objective
To determine the aluminum content in Reynolds Wrap and Great

Value foil using Spec-20 colorimeter.
Introduction
Visible light is a very small part of the electromagnetic
spectrum that the naked eye can see. White light
contains a spectrum of different wavelengths and when it is
passed through a prism, the light is broken
up into its different colors. Below is a table of different colors
and the wavelengths associated with
them.
How we perceive color is due to how the different wavelengths
are either absorbed or reflected
by a substance. The part of every material that absorbs the light
is known as a chromophore. If
something appears red, it is because most of the other colors
(wavelengths) are absorbed, except the

red light which is reflected.
One way to measure absorbance is with a Spec-20 colorimeter.
A Spec-20 is a device that
measures the absorbance of particular wavelengths of light by a
specific solution. The absorbance of a
specific compound can change with the concentration. The
simplest way to think of concentration is
how much something is dissolved in something else. One is able
to use a known concentration to find
the concentration of an unknown sample. This can be done
using the formula M1V1 = M2V2, where M is
equal to Molarity and V is equal to the Volume.
In this lab, we will be looking at the absorbance of various
solutions containing different concentrations
of aluminum.
The colors of the visible light spectrum
color wavelength interval
red
~ 700–635 nm
orange

~ 635–590 nm
yellow
~ 590–560 nm
green
~ 560–490 nm
blue
~ 490–450 nm
violet
~ 450–400 nm
http://en.wikipedia.org/wiki/Red
http://en.wikipedia.org/wiki/Orange_(colour)
http://en.wikipedia.org/wiki/Yellow
http://en.wikipedia.org/wiki/Green
http://en.wikipedia.org/wiki/Blue
http://en.wikipedia.org/wiki/Violet_(color)
Experimental Procedure
Weigh out approximately 50 mg of Reynolds Wrap aluminum
foil into a 50 mL beaker. Record the exact
weight of the sample into your notebook. Dissolve the foil
using 25 mL of 4 M hydrochloric acid and
transfer the solution to a 100 mL volumetric flask. Rinse the
beaker with portions of deionized water
and add to the volumetric flask to ensure complete
(quantitative) transfer of the solution. Dilute the

sample to the line with deionized water. This is your stock
solution.
Obtain three 25 mL volumetric flasks and label them 1 – 3.
Transfer 1.0 mL of the stock solution into
each flask followed by addition of 1 mL of the aluminon/buffer
solution and 1 mL of the ascorbic acid
solution. Dilute the solutions to the line with deionized water
and allow them to stand for 15 minutes.
Calculate the concentrations of the solutions in your notebook
in mg/L (make sure to account for the
dilutions). Repeat the above procedure using Great Value
aluminum foil (make sure you keep the two
trials Reynolds Wrap vs. Great Value separate from each other
and organized).
While the solutions are standing, move to a lab station with the
spectrometer setup. Each station will
contain a set of cuvettes, standard samples and a blank sample
which will be used to construct a Beer’s
Law plot. Obtain a blank sample and fill one of the cuvettes
approximately ¾ of the way to the top.
Make sure the wavelength on the instrument is set to 530 nm
and insert your sample into the
compartment. Zero out the instrument. Next, obtain one of the
standard sample solutions and record

the concentration into your notebook (see table below). Fill up a
second cuvette ¾ of the way and insert
into the instrument. Close the compartment and record the
absorbance value into your notebook.
Repeat for each additional known sample.
Sample Concentration (mg/L) Absorbance
Blank
Known 1
Known 2
Known 3
Known 4
Known 5
After your Reynolds Wrap and Great Value aluminum foil
solutions have been sitting for 15 minutes,
determine the absorbance values for each sample using the
spectrometer. Record your values in your
notebook.
Sample
Concentration

(mg/L)
Absorbance 1 Absorbance 2 Absorbance 3
Average
Absorbance
Reynolds
Wrap
Great Value
Once you have finished, dispose of the liquid material in the
bottle labelled “Aqueous Waste”.
Part II: Data Analysis
Construct a standard curve using your values from the standard
solutions by plotting the absorbance
values for each standard versus the concentration of the sample.
Construct a best fit line (trendline) and
obtain the equation of the line and the R2 value. Using the
equation of the line, determine the actual
mass of aluminum metal present in both Reynolds Wrap and
Great Value aluminum foil.

Experiment #3a Aluminum Content via REDOX Reaction Ob.docx

Experiment #3a Aluminum Content via REDOX Reaction Ob.docx

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