Quality Control for the Athenium Baking Soda Company
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Transcript of Quality Control for the Athenium Baking Soda Company
Quality Control for the Athenium Baking Soda Company
November 3, 2010
Kaleigh WoodJack DupeeChristina MontfordColby Whitehead
Introduction:
Baking soda, also known as sodium bicarbonate, is used in many aspects of our daily
lives. With the chemical formula of NaHCO3, baking soda is a chemical salt. Baking soda is
able to neutralize many acids and can break down many proteins. Therefore, baking soda is
often used as leavening agent when baking; it causes the dough to rise. Also, with the ability to
act as a neutralizer allows it to commonly be used as a deodorizer. As a result of its many
common uses the Athenium Baking Soda Company has decided to produce it. In order to
produce their baking soda, the company uses the following method of reacting ammonium
bicarbonate and brine (sodium chloride/ salt water)
NH4HCO3(s) + NaCl(aq) NaHCO3(aq)+ NH4Cl(aq)
While this is a valid means the brine that the company uses contains unknown amounts of
potassium chloride (KCl), lithium chloride (LiCl), and calcium chloride (CaCl2). Therefore
when the baking soda is dried to form the solid, final product, that the company wants, the
product may contain any of the three previously mentioned chlorides. In order to determine the
product’s quality (purity) and definite composition we will perform two experimental
procedures.
The first procedure will be a thermal gravimetric analysis. This procedure will be used in
order to calculate the percent composition of the sodium bicarbonate in the company’s sample
just like the first procedure did. In this experiment, we will begin by adding a sample of a
known mass of the company’s baking soda to a crucible. Then, the sample will be heated until it
has decomposed to form solid sodium bicarbonate, gaseous water, and gaseous carbon dioxide.
2NaHCO3(s) Na2CO3(s) + H2O(g) + CO2(g)
After we have reheated the crucible to ensure accuracy, the stoichometric ratio for the mass loss
of H2O and CO2 per gram of NaHCO3 can be determined. Also, we will be able to determine the
mass of H2O and CO2 lost when heating. This information is then used to determine the mass of
NaHCO3 present in the company’s sample. Further, we can then determine from this
information the percent by mass of the NaHCO3 in the sample. If the percent by mass does not
equal 100%, or really close, then it will be determined that there are contaminants in the sample.
The second procedure will be the titration of a solution that contains a sample of the
company’s baking soda. We are doing a second procedure in order to check the accuracy of the
first experimental procedure. This experiment will help to determine the percent by mass of the
sodium bicarbonate in the solution. First, we will prepare the solution by adding the solid
sodium bicarbonate (Na2CO3) into an aqueous solution which will act as a standard base. Then,
this solution will be used to titrate an aqueous solution of the company’s baking soda (NaHCO3).
After the titration is complete, the equivalence point and the amount of Na2CO3(aq) needed will be
used to determine the molarity of the sodium bicarbonate in the solution. From the molarity, we
will then determine the mass of the NaHCO3 present in the solution. Finally, the mass of the
acetic acid in the solution is used along with the mass of the sodium bicarbonate in order to
determine the percent by mass of the baking soda in the solution. If the calculated mass is not
equal to the mass of the baking soda sample, then we will know that there are contaminants in
the company’s baking soda.
Once we have determined if there are, in fact, contaminants in the company’s baking
soda, we will use emission analysis to determine which contaminants are present in the sample.
The possible contaminants we are looking for are lithium chloride, potassium chloride, and
calcium chloride. To begin this experiment we will measure in nanometers the wavelengths of
the metal ions that could be present in the sample (Li+, K+, Ca2-) by using emission spectroscopy.
From the gathered information, we will determine the most intense wavelengths found in an
aqueous sample of the company’s baking soda by comparing them to the known wavelengths. In
doing so, we will be able to determine which contaminants are present in the company’s sample.
After we have successfully performed these three procedures we will have determined the
percent by mass of the NaHCO3 in the Athenium Baking Soda Company’s sample. Also, we
will have determined if any of the possible contaminants are in the company’s baking soda.
Procedures
Part 1: Decomposition of Baking soda for determination of Percent by mass
1. Obtain a crucible and lid.
2. Add 3 mL of 6 M HCl. Let sit for 5 minutes.
3. Clean out the excess residue with a spatula.
4. Pour residue and remaining acid into the waste container.
5. Rinse out crucible with copious amounts of distilled water.
6. Obtain a Bunsen burner, clay triangle, iron ring, and wire gauze.
7. Set up clay triangle on the iron ring above the Bunsen burner. The wire gauze will be used for
cooling.
8. Heat crucible with lid not completely covering the top for five minutes. The bottom of the
crucible should be glowing red.
9. Remove crucible from triangle to wire gauze to cool. Allow cooling until room temperature.
Weighing a hot crucible can cause a miss reading.
10. Find the mass of the crucible and lid
11. Add ~1 gram of Baking soda. Record the exact mass.
12. Put crucible containing baking soda in the clay triangle. Gently heat for 5 minutes; make sure
the baking soda is not melt.
13. After the 5-minute gentle heating, vigorously heat for 15 minutes.
14. Remove crucible from flame and allow cooling until room temperature.
15. Weigh crucible and record mass.
16. Heat crucible again gently for 5 minutes and vigorously for 5 minutes. Allow cooling. Weight
and record mass.
17. If the mass from 15 and 16 are not within .005 g of each other. Repeat step 16 until they are.
18. Record the final mass of the cool crucible, lid, and mixture.
19. Repeat steps 1-18 with a second sample.
20. Clean crucible as done in steps 2-5.
21. The following steps should be done outside of class.
22. Calculate the stoichiometric ratio for the mass of the lost from carbon dioxide and water per
gram of sodium bicarbonate decomposition.
23. Calculate the mass of carbon dioxide and water lost from the baking soda.
24. Calculate the mass of sodium bicarbonate in the original baking soda
25. Calculate the percent by mass of sodium bicarbonate in the baking soda.
Part 2: Standardization of Hydrochloric acid solution
1. Weigh out approximately 1 grams of Sodium Carbonate in to a 250 mL beaker. Record the
exact mass of Sodium Carbonate
2. Add sufficient distilled water to dissolve the Sodium Carbonate. Record the volume used.
Make sure there is enough water to completely submerge the cut-out notch on the tip of the pH
electrode.
3. Set up the MeasureNet drop counter, pH probe, and buret2
a. Obtain a 50-mL buret. Rinse with distilled water, and be sure to rinse tip. Make
sure tip is closed. Add 5 mL of HCl solution to buret. Rinse buret by tilting it on
its side and spinning. Drain the solution through the tip. Discard HCl in to the
waste container. Flush out buret with copious amounts to distilled water.
b. Make sure tip is closed. Fill buret with the 1.0 M HCl solution. Drain one mL
to insure there are no air bubbles in the tip. Record the volume.
c. Press the on button to turn on the MeasureNet workstation.
d. Hit Main Menu then F3 pH/mV.
e. Place pH probe in 7.00 pH buffer solution. Measure the temperature.
f. Hit Calibrate. Insert the Temperature and press enter.
g. When prompted for pH of the buffer solution insert 7.00 and hit enter. Wait for
pH level on the display screen to level out then press enter.
h. Rinse the pH probe with distilled water then dry with a KimWipe carefully.
i. Place pH probe into the solution. The probe should be completely submerged, if
not add distilled water.
j. Turn magnetic stir bar on to a low level. This should be no higher then between
levels 2 and 3.
k. Double check that the buret is lined up correctly with the drop counter.
l. Press start and insert the initial volume of HCl in the buret. Press enter. Record
in lab the initial volume as well.
m. Press start and open the buret just enough to create drops. Make sure the red
light on the drop counter is flashing each time a drop passes through.
n. Watch the pH levels. They will first decrease slowly. Then rapidly decrease.
Then level out. When the pH levels off the titration is over. Press stop.
o. Record the final volume and press enter; record in notebook as well.
p. Hit File Options then F3 and insert the three-digit code. Press enter.
q. Return the cleaned pH probe to the buffer solution.
4. The titration above should be done a total of two times with the Sodium Carbonate solution.
5. Create a titration curve with data obtained above2. This should be done out side of class.
a. Open information obtained above.
b. Copy and paste information in to excel.
c. Go to insert graph and select scatter smooth line.
d. Open chart tools. Select Layout and delete legend.
e. Select Chart title and name graph.
f. Select axis titles. X is volume in mL and Y is pH levels of solution
g. Find the equivalence point. This is where the slope of the line goes from
increasing to decreasing. This does not mean the slope is negative.
h. Email graph to your group
i. Print graph.
Part 3: Determination of the moles of NaHCO3
1. Repeat all steps above however replace the Sodium Carbonate with Baking soda.
Part 4: Emission Analysis
1. Set up a Bunsen burner near a MeasureNet spectrophotometer
2. Turn on the MeasureNet spectrophotometer by pressing the on button.
3. Press Main Menu, then F5 Spectroscopy
4. Then press F1 Emission
5. Press Setup
6. Then press F1 to set the limits. For the Y-axis they should me 0 to 1500. For the x axis, leave
as default.
7. The MeasureNet is now set up and ready to record.
8. Obtain a small beaker with hydrochloric acid solution in it to be used to clean the nichrome
wire between each use. This is done by placing the wire in the acid for 30 seconds. Then rinse
with water. Then heat in flame until all water is gone.
9. Create a baking soda sample solution to be tested by completely dissolving ~ 1 gram of baking
soda in 25 mL of distilled water in a clean beaker.
10. Between each test the burner must be cleaned. This can be done by this process. distilled
water must be poured onto a watch glass. Then heat the testing wire until red-hot. Hold watch
glass close to the bottom air intake of the burner. Place wire in to water to allow water vapor to
go through the burner and clean it of any particles.
11. Next obtain 4 other watch glasses. Pour a small amount of the baking soda solution in to one,
Calcium chloride solution in to another, Potassium chloride solution in to another, and Lithium
chloride solution in to the final. Make sure to keep track of which one is which.
12. It is now time to calibrate the spectroscopy.
13. Enter the station number into the MeasureNet system and press Enter.
14. Cover the end of the fiber optic cable with your finger and press Zero. Make sure to leave
covered until workstation reads “ready to scan”
15. Press Intensity. Heat the wire until glowing orange.
16. Adjust the fiber optic cable until reading is somewhere between 2500-4000. Press intensity.
Ready to scan will reappear
17. Clean the burner with distilled water. Repeat multiple times to make sure there is no left over
residue from past experiments.
18. It is now time to test each solution. This is done by tilling the watch glass so the solution is
right under the burner. Heat wire until glowing hot. Place the tip into the solution. **a lab
partner must press sample on the spectrophotomer right before the wire makes contact to get a
good sample**
19. Record the color made. Pour out remaining solution in to the waste container.
20. Press file options. Press F3 to save the scan. Make sure to keep track of the saved number for
each.
21. Repeat steps 17-20 for each solution.
22. Create a XY scatter plot for each scan. This is done out side of class.
23. Compare the graphs of the 3 known solutions to the baking soda. What can be told from the
comparisons?
Results
Part 1
1. Trial 1 data
Mass of crucible = 36.085 grams
Mass of crucible and Baking Soda = 37.087
Mass of crucible and Baking Soda after 1st heating = 36.726
Mass of crucible and Baking Soda after 2nd heating = 36.721
2. Stiochiometric ratio for loss of carbon dioxide and water per gram of sodium bicarbonate
2NaHCO3(s) Na2CO3(s) + H2O(g) + CO2(g)
Grams of water per gram of NaHCO3 =
(1 gram NaHCO3)(1 mol of NaHCO3 / 74.99 grams of NaHCO3)(1 mol water/ 2 mol NaHCO3)(18 grams of water/1 mol water) = .1200160021 grams of water
Grams of carbon dioxide per gram of NaHCO3 =
(1 gram NaHCO3)(1 mol of NaHCO3 / 74.99 grams of NaHCO3)(1 mol carbon dioxide/ 2 mol NaHCO3)(44.01 grams of carbon dioxide/1 mol carbon dioxide) = .2934391252 grams of water
For every 1 gram of NaHCO3, .4134551273 grams of water and carbon dioxide are produced
3. Calculate the mass of sodium bicarbonate.
37.087 grams of baking soda – 36.721 grams of baking soda after heating = .366 grams of water and carbon dioxide
(.366 grams of water and carbon dioxide)(1 gram of NaHCO3/ .4134551273 grams of water and carbon dioxide) = .8852230287 grams of NaHCO3
.88522 grams with significant figures
4. Calculate the percent by mass.
[(.8852230287 grams of NaHCO3)/(1.002 grams of baking soda)](100) = 88.34 % by mass of NaHCO3
Part 2
1. Preparation of HCl solution
2. Standardization of HCl with Sodium Carbonate - trial 1
3. Standardization of HCl with Sodium Carbonate - trial 2
4. What is the molarity of the HCl solution used in trial 1 and 2
5. What is the average molarity
Part 3
1. Preparation of Baking soda solution data.
2. Titration of baking soda solution with standardized HCl – trial 1
3. Titration of baking soda solution with standardized HCl – trial 2
4. Determine the moles of HCl required to neutralize the solution.
5. What is the average molarity of the solution?
6. What is the percent by mass of NaHCO3 in the baking soda? What is the average?
7. What does it say about the baking soda?
Part 4
1. Compare the baking soda emission spectrum to the three known solution spectrums. What can we tell from this comparison?
Lithium
Potassium
Calcium
Baking Soda
Based on the graphs there appears to be calcium in the baking soda
Bibliography:
1. Whitten/Davis/Peck/Stanley. Chemistry. California: Mary Finch. Print.
2. Whitten/Staton/Atwood. General Chemistry Supplement. Vol. 1. Mason: Cengage,
2009. Print.
3. "What Is Baking Soda?" WiseGEEK: Clear Answers for Common Questions. Web. 01 Nov.
2010. <http://www.wisegeek.com/what-is-baking-soda.htm>.