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Name:
Lab 2: Biodegradable Soap
Question:
Are natural, homemade soaps better or worse for our skin compared to generically mass-produced soaps?
Background:
Would you prefer your soap ingredients to read like this: Sodium tallowate, sodium cocoyl isethionate, sodium cocoate,
sodium laurel sulfate, water, sodium isethionate, stearic acid, coconut fatty acid, fragrance, titanium dioxide, sodium
chloride, disodium phosphate, tetrasodium EDTA, trisodium etidronate, BHT, FD&C blue no. 1, D&C red no. 33. Or this
way, the way a true natural soap lists ingredients: Olive, Castor, Coconut and Palm Oils; Sodium Hydroxide; Mountain
Spring Water; Goat Milk; Lavender Essential Oil.
When you are evaluating whether or not a soap is truly natural, you do not want to see artificial or chemical colorants,
hardeners, latherers or preservatives in the ingredient list. A truly natural soap will not have been made using those
ingredients. The next time you walk down the soap aisle at your favorite store enjoying the fresh, clean scents and the
bright colorful packaging, pay attention. Look at the labels. The vast majority of the products on the shelf don't say
'soap' on their labels. They might be called beauty bars, moisturizing bars, or body bars, but not soap. That's because
these bars aren't actually soap and can't legally claim to be; they're detergents. The manufacturers have removed most
of the 'good' stuff that occurs in the soap making process, and replaced it with synthetic lathering agents and harsh
chemicals. These cheap, plentiful detergent bars are not only bad for your skin, but they're also bad for the planet, too.
Commercial soap manufacturers make it a practice to remove the glycerine that is produced during the saponification
(soap-making) process. The glycerine is a highly profitable substance, often sold to other companies who use it to make
lotions and moisturizers, which your skin, now dried out from the harsh detergent 'soap,' desperately needs.
Most commercially produced bars contain synthetic lathering agents, artificial colors, and a slew of chemicals we can't
even pronounce. Antibacterial and antimicrobial soaps often contain triclosan. Triclosan is a toxic chemical that is known
to cause cancer. According to the National Coalition Against the Misuse of Pesticides (NCAMP), manufacturers of a
number of triclosan-containing products claim that the active ingredient continues to work for as long as 12 hours after
use. Consumers are, therefore, exposed to triclosan for much longer than the 20 seconds it takes to wash their hands or
face.
Always remember that your skin is porous and absorbent. It absorbs whatever it comes in contact with, much the same
as sticking something in your mouth. Chronic use of chemical loaded products will cause the body to store the chemicals
in the body fat or even in the brain. With enough accumulations of toxins in the body, illness can occur.These nasty
chemicals and toxins are now finding their way into our eco-system. Every time that lather goes down the drain, those
pollutants are going with it. A recent report by the UK's Royal Society of Chemistry (RSC) revealed that synthetic
chemicals from soap, body washes, shampoos and other healthcare products were sneaking through the filters at water
purification plants. The list of offenders included phthalates, which are linked to reproductive disorders in both humans
and animals, and parabens, a preservative, which links to cancer.
All natural, organic, handmade soap is a great alternative to generic soaps. The two main methods to make soap "hot
process" and "cold process." Cold process soap bars are made using a combination of oils or fats and lye. All of the
corrosive qualities of the lye are removed during the saponification process. When the lye interacts with the oils or fats,
it creates glycerine. The type of oils and fats used make a difference in how hard or soft the soap bar ends up being, and
how well it lathers.
The preparation of soaps involves a chemical reaction called saponification. Natural soaps are sodium or potassium salts
of fatty acids, originally made by boiling lard or other animal fat together with lye (Sodium hydroxide; NaOH) creating
glycerol and crude soap.
The use of cosmetic products, especially soaps, have profound influence on skin surface pH. Popular soaps have a pH
value generally around 8.0, will increase skin pH from its 'natural' pH value of on average a 5. It is demonstrated that
skin with pH values below 5.0 is in a better condition than skin with pH values above 5.0, as shown by measuring the
skin’s function as a protective barrier, as well as moisturization and scaling. Humans’ naturally acidic skin keeps healthy
bacterial growth attached to the skin, whereas an alkaline pH of 8-9 promotes the removal of necessary bacteria from
the skin.
Acidic and basic are two extremes that describe a chemical property of compounds. A substance that is neither acidic
nor basic is neutral. The pH scale measures how acidic or basic a substance is. The pH scale ranges from 0 to 14. A pH of
7 is neutral. A pH less than 7 is acidic. A pH greater than 7 is basic. Pure water is neutral. But when chemicals are mixed
with water, the mixture can become either acidic or basic. For example, lye, a common ingredient used to produce
biodegradable soaps is 13, thus extremely basic.
Generic soap is generally made up of animal or vegetable fat and corrosive sodas, with added perfume, colors and
extracts. Although it is a very efficient formula to remove grease and dirt from the skin, it tends to also dry the skin. The
problem with generic brand-name soaps is their alkaline ingredients, while our skin tends to be slightly acidic. As a
result, immediately after washing your skin with soap, the skin's protective acid mantle is disturbed and you may feel
tautness and dryness on your skin.
Introduction:
Your introduction for this lab should include the following items:
- Purpose (WHAT are you trying to determine in this lab and HOW are you going to determine that)
- Background information (to support your WHAT and HOW aspects of your purpose)
- Explanation of biodegradable & saponification
- Explanation of the benefits of using naturally made, biodegradable soaps
- Explanation of how the biodegradation process is an example of the law of conservation of mass
Pre-Lab:
1. Based on the representation of saponification provided in the background, what type of chemical reaction can
saponification be classified as?
2. Define saponification
3. Define the law of conservation of mass
4. Based on the background reading, your skin has a natural pH of what?
5. Based on the background reading, most generic, mass produced soaps have a pH of what?
6. Based on the background reading, what would be the most ideal pH for soaps that we use on our skin?
7. Based on the background reading, what are some negative effects that generic, mass produced soaps have on
skin?
8. How will your soap differ from mass produced, brand name soaps?
9. What substances will you be using that will undergo saponification? Reference the materials list for this lab.
Hypothesis:
In order to produce natural, biodegradable soap you will be combining various oils with lye. Based on the background
information provided, do you think your naturally produced soap will be more or less harmful for your skin? Use
evidence from above to support your hypothesis.
Materials:
- Gloves
- Goggles
- Apron
- Stirring rod
- 100 mL graduated cylinder
- 1 large glass beaker
- 250 mL Erlenmeyer flask
- Plastic spoon
- hot plate
- Thermometer
- Grapeseed oil
- Coconut oil
- Olive oil
- Lye (NaOH)
Procedures:
1. Using an electronic balance, plastic spoon, and a large glass beaker, weigh out 12g of coconut oil and set to the
side. Record the exact mass of coconut oil measured in the Data section below.
2. Using an electronic balance and 100mL graduated cylinder, weigh out 30g of olive oil. Record the exact mass of
olive oil measured in the Data section below, and pour the olive oil into the large glass beaker.
3. Using an electronic balance and 100mL graduated cylinder, weigh out 16g of grapeseed oil. Record the exact
mass of grapeseed oil measured in the Data section below, and pour the grapeseed oil into the large glass
beaker.
4. Place the large glass beaker with oils on the hot plate and turn the temperature to high (~level 10). Heat the oils
up to about 100-120°C. Check the temperature of the oils using the thermometer. Once the oils have reached a
temperature within the designated range, remove the large glass beaker from the hot plate. While waiting for
the oils to heat, continue on to the next steps.
5. Thoroughly rinse out the 100mL graduated cylinder with water and shake out as much of the excess water as
possible.
6. Using the electronic balance, weigh the empty 100mL graduated cylinder and record the exact mass of the
cylinder in the Data section below.
7. Using the graduated cylinder measure out 22mL of Lye solution. Be EXTREMELY careful when handling the lye
solution.
8. Using the electronic balance, weigh the graduated cylinder with Lye and record the exact mass of the cylinder
with lye in the Data section below.
9. Pour the Lye solution into the 250mL Erlenmeyer flask and using the hot plate (set at level 10), heat the Lye
solution to 100°C. Use the thermometer to track the temperature of the Lye solution.
10. Once the Lye solution has reached the desired temperature, carefully pour the lye solution into the large glass
beaker of oils and begin stirring vigorously using the stirring rod. The mixture will become cloudy and then
start to thicken. After about 3-5 minutes of mixing, what you’re looking for is “trace”. This is when the
solution reaches a runny pudding-like consistency. If you lift the stirring rod out of the soap and it
leaves marks on the surface, you’ve reached trace.
11. Once you have reached trace, quickly come pour your sample into the muffin tin molds located at the front of
the classroom. Use water to thoroughly rinse out all used glassware and return all supplies to their designated
locations.
Data:
Law of conservation of mass Mass of 100 mL graduated cylinder =
Mass of Lye + graduated cylinder =
Mass of Lye =
Mass of Coconut Oil =
Mass of Olive Oil =
Mass of Grapeseed Oil =
Total Mass of Soap Ingredients =
Mass of soap after saponification =
Soap pH pH of Liquid Hand Soap =
pH of Homemade Soap =
Post-Lab Questions:
1. Based off your pH measurements and the pH scale shown above, is liquid hand soap acidic or basic?
2. Based off your pH measurements and the pH scale shown above, is the homemade soap acidic or basic?
3. What do you expect the final mass of your soap bars to be once they harden? How do you know?
4. Does the final mass of your soap bar equal the total mass of soap ingredients you calculated while making the
soap? If not, what may have occurred throughout the soap making process that altered your expected results?
Conclusion:
When writing your conclusion, consider RERUN. Be sure to answer the purpose to the lab, and discuss whether you
reject or accept your hypothesis. As always, use your data and observations to support your conclusion. Reference your
responses to both Pre-lab and Post-lab questions to strengthen your conclusion.