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Objective: The purpose of today's lab is to create glycerol through a process known as saponification: a process that is performed through the hydrolysis of an ester. The result of this lab will be soap, that will then be tested for pH and bubble height and compared to the soap products of two other classmates after a 1 week curing period.
Compounds of Study:
Sodium Hydroxide
Sodium Hydroxide
Formula: (NaOH)
Molar Mass: (39.99 g/mol)
MP: 323 °C
BP: 1,388 °C
Polarity: Polar
Image Source: Ozcanium Chemical Source
Water
Water
Formula: (H2O)
Molar Mass: (18.01 g/mol)
MP: 100 °C
BP: 100°C
Polarity: Polar
Image Source: Earth.com
Pre-Lab: Completed In Work-Sheet Form during Lab.
Methods:
Activity #1:
38 mL of water was measured in a graduated cylinder.
25.41 g of sodium hydroxide was measured in a very clean glass flask.
The 38 mL of water was poured into the flask containing sodium hydroxide and the sodium hydroxide and water solution was mixed with a glass rod.
The flask was then placed in an ice bath to cool until the temperature in the flask reached 20 degrees Celsius.
While the hydroxide and water solution cooled, 127.10 g was measured into a large beaker weighing *** grams.
45.53 g of coconut oil and 9.07 g of castor oil were measured and then poured into the same beaker.
The flask containing the hydroxide solution and the beaker containing the oil solution were then placed on a hot plate set to "2".
Both solutions were left to heat up with intermittent stirring until the solutions came to 40 degrees Celsius.
Once the solutions reached the desired temperature, the solutions were taken off the hotplate, and the hydroxide solution was poured into the beaker containing the oil solution.
The new product was then gently mixed with an immersion blender. This was done until the solution reached a medium trace and peaks formed in the solution that kept their shape when the blender was removed.
A total of ~3 ml of lemon essential oil and ~3 ml of sweet wild orange essential oil were added and mixed into the product with a spatula for smell.
Two drops of pink coloring were added to the product and folded in with a spatula for visual aesthetics.
The soap product was then transferred into four molds and left to harden over the next week.
Activity #2:
The remainder of the soap product was then used to run experimental analysis.
Approximately 0.25 g of soap was added to 5 mL of water to test the pH of the solution. The pH was documented and then compared to the soap products of Justin Young and Elliot Vargas.
Approximately 0.25 g of soap was added to 5 mL of water and then vigorously shaken. The bubble height of the shaken solution was then measured immediately after shaking, at 1 minute, 2 minutes, and 3 minutes. The bubble height was then compared to the soap products of Justin Young and Elliot Vargas.
Approximately 0.25 g of soap was added to 5 mL of water with 5 drops of magnesium chloride. The bubble height of the shaken solution was then measured immediately after shaking, at 1 minute, 2 minutes, and 3 minutes. The bubble height was then compared to the soap products of Justin Young and Elliot Vargas.
The above experimental proceedings were then repeating after leaving the soap to cure over the next week.
Results:
A total of 188.89 grams (189 mLs) of soap was formed as the final product. This soap was placed into four molds that were shaped like various flowers. (See Image 1 Below)
The pH of the soap was tested immediately after tracing was completed. The initial pH was 14. A pH reading was taken again after a one-week curing period and the pH was determined to be 10.
The pH readings of two other classmates' soaps were taken.
Justin Young-Bach's Initial Soap pH: 13.5, pH after one week: 9.
Elliot Vargas' Initial Soap pH: 13, pH after a one-week 8.5.
A bubble height test was performed.
My soap's bubble height immediately after tracing:
Initial Bubble Height: 5.25 mL 1 min: 5.50 mL 2 mins: 5.00 mL 3 mins: 5.00 mL
My soap's bubble height after one-week curing period:
Initial Bubble Height: 6.00 mL 1 min: 5.75 mL 2 mins: 5.50 mL 3 mins: 5.50 mL
Justin Young-Bach's bubble height immediately after tracing:
Initial Bubble Height: 7.00 mL 1 min: 6.60 mL 2 mins: 6.50 mL 3 mins: 6.30 mL
Justin Young-Bach's bubble height after one-week curing period:
Initial Bubble Height: 10.00 mL 1 min: 9.00 mL 2 mins: 9.00 mL 3 mins: 9.00 mL
Elliot Vargas' bubble height immediately after tracing:
Initial Bubble Height: 8.50 mL 1 min: 7.40 mL 2 mins: 7.60 mL 3 mins: 7.30 mL
Elliot Vargas' bubble height after one-week curing period:
Initial Bubble Height: 9.70 mL 1 min: 9.10 mL 2 mins: 8.60 mL 3 mins: 8.50 mL
A bubble height with hard water test was also performed.
My soap's bubble height immediately after tracing:
Initial Bubble Height: 5.75 mL 1 min: 5.25 mL 2 mins: 5.00 mL 3 mins: 5.00 mL
My soap's bubble height after a one-week curing period:
Initial Bubble Height: 5.00 mL 1 min: 5.00 mL 2 mins: 5.00 mL 3 mins: 5.00 mL
Justin Young-Bach's bubble height immediately after tracing:
Initial Bubble Height: 5.80 mL 1 min: 5.80 mL 2 mins: 5.80 mL 3 mins: 5.80 mL
Justin Young-Bach's bubble height after one-week curing period:
Initial Bubble Height: 6.00 mL 1 min: 6.00 mL 2 mins: 6.00 mL 3 mins: 5.50 mL
Elliot Vargas' bubble height immediately after tracing:
Initial Bubble Height: 5.20 mL 1 min: 5.10 mL 2 mins: 5.10 mL 3 mins: 5.10 mL
Elliot Vargas' bubble height after one-week curing period:
Initial Bubble Height: 8.6 mL 1 min: 8.50 mL 2 mins: 8.50 mL 3 mins: 8.50 mL
Image of the soap product after one week of curing:
Image of the soap product after one week of curing:
Image 1
Conclusion: Discussed at length in Writing Assignment #1.
Post-Lab: Completed during lab in worksheet form.
Lab #1 Post-Lab.pdfReflection: While I have made my own soap previously in a chemistry club activity, I have never made the lye solution "from scratch." This lab gave me a deeper understanding of the chemical processes of saponification and its practical uses for making soap. If I were to repeat this experiment I would mix my soap and lye solution for a much shorter period of time to create a thin-medium trace, this would hopefully allow the soap to form better in the molds by allowing saponification to occur at a slower rate, leading to decreased soap pH and increased bubble stability.
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