This was a lab to learn about emulsions, fats, soap, polarity and how molecules bind to create new substances.
Through this Instructable we will explain the process that we used to make our own soap and the key concepts you need to know to create your own.
104 grams of pure coconut oil
36 mL of water
18.72 grams of lye
3 drops of lavender oil
A pinch of oatmeal
For this experiment you need. . .
A hot plate or stove
1000 mL heat resistant beaker
250 mL beaker
100 mL graduated cylinder
Magnetic Stir Bar
Step 1: Measure Ingredients
We began by measuring out the desired amount of room temperature coconut oil. You can pick any oils or fats for this process, but coconut oil is excellent for the skin. Please be aware that the amount of oils/fats used will be roughly how much soap you will have. Once the amount of your oil is determined use a online saponification calculator like the one we used on SoapCalc.net to determine how much water and lye you need unless using a pre mixed solution. The ration for the lye and fat should be 1:3.
Step 2: Liquid Vs. Solid Fats
If your oil is not already in liquid form, warm it to liquid point. The melted oils could be between 49 and 54 degrees celsius before anything else is done. If your fat/oil is already in liquid form, this could mean that it is unsaturated and polyunsaturated. This just means the there are one or more double bonds in the triglyceride fatty acids. This makes the fatty acids fold more and therefore unable to be solid at room temperature. An example of of unsaturated fat is olive oil, and vegetable oil. Saturated fats have no double bonds and are solid at room temperature such as butter and coconut oil. The fatty acids in saturated fats are straight therefore more stable and easier to stack, allowing a solid to form.
Step 3: Saponification
To continue your soap making process, mix in your measured water first, then carefully add the lye. Please take special care of handling the lye. Due to its extremely basic property, avoid touching your skin or any mucus membranes, wear gloves and proper eye protection. Added the lye and water will start the saponification process. Saponification is when a triglyceride (fat) is added with lye. The triglyceride (any three fatty acids and a glycerol) is broken apart into three separate glycerols and sodium stearate is created making what we know as soap. During this time, three water molecules are removed. This is called the dehydration process. Sodium stearate is amphiphilic meaning one side of the molecule is hydrophobic (avoids water) and the other side is hydrophilic (attracts water). These molecules group together to create micelles cells where the hydrophilic ends form a circle with the hydrophobic ends in the inside. Soap cleans us because the ionic heads the non polar dirt and grease become trapped into the hydrophobic center of circle, then break apart and washed away with water.
Step 4: Take a Break and Watch Soap Happen
This happens to be the most tedious part of the process. You must allow the soap to thicken properly and let the sides fall in, while keeping the temperature between 49 and 54 degrees celsius. When the lye was added, don't be surprised if the temperature rises rapidly. This is due to energy being released by the reaction. Vigilantly stir the mixture for 20-30 minutes or until properly thickened. If your soap was properly made the mixture should have a balanced pH. Too much lye will cause the soap to be basic, therefore burning the skin and too much oil could cause the soap to be acidic. Without the proper amount of lye, the soap could lose the bubbly property that we all love. Along with a yellow rubber ducky.
Step 5: Completing the Soap
Once your substance begins to thicken, you can add drops of chosen essential oils to make the soap smell good. We also added oatmeal to our soap as an exfoliant. By adding things like oatmeal or coffee grinds, you can change the scrubbing ability of your soap. It is also good to know before using your soap what the pH of the substance is. While your soap is still at this stage, test the pH to make sure that it is ranges between 8 and 9. If it is above 10, then the soap would be too basic for use making it irritable to the skin. This means that there would be too much lye that did not react with the fats and oils.
DON'T FORGET TO TAKE OUT STIRBAR BEFORE LETTING THE SOAP SIT
Step 6: Discussion
Our soap is very moisturizing, creamy, sudsy and gentle. It's much more creamy than the commercial soap you can get at the store and also smells different, but better then soap usually does. Compared to another's group our soap was effective and our ratio was properly devised. While another groups separated, ours was completely mixed and took a solid form. This was mostly likely due to our soap ratio was correct and the others group used too much lye. Ben G and Zack W.'s soap used lard and olive oil, which Ben called a bad idea. He felt that their soap was too basic to use. Our soap was probably as good as it was due to the beneficial properties of the coconut oil and the natural exfoliation of oatmeal.
Step 7: Clean Up
When this Lab has been completed, there are a few more things to be done. Even though the picture above looks nice and tidy, that is not what needs to be done to have cleaned up your area. Be sure to clean your beakers and thermometers with soap and water and let them dry on paper towels. Wrap up your hot plate and then clean your area with soap and a paper towel to get all oily spots off of the surface.
Step 8: Don't Forget to Have Fun
Why did the white bear dissolve in water?
Because it was polar.