Chemistry Reference
In-Depth Information
to 110 degrees Fahrenheit (
°
F) (38 to 43 degrees Celsius [
°
C]), then
remove from the heat.
8. Once the oil mixture and lye mixture have both cooled to
approximately 100
°
F (38
°
C), slowly add the lye mixture to the oil
mixture while stirring.
9. Blend the mixture with a stick blender until it is evenly mixed and
has thickened so that a drip of the mixture leaves a trace along the
surface of the liquid that does not immediately disappear.
10. Add 1 to 2 tbsp of fragrance oil to the soap mixture and blend.
11. Add 1 to 4 drops of color to the mixture, if desired. Blend well for
even color, or stir slowly for a swirled appearance.
12. Remove a small amount of the soap mixture on a spatula and place
in a test tube. Add a drop of phenolphthalein, an acid-base indicator
that remains clear in acidic conditions but turns bright pink if the
pH rises above 8.2. If the indicator remains clear or turns a pale
pink, the soap will be safe to use on your skin when the process is
complete. If it turns bright pink, it will be too basic for use on the
skin. It may be used on clothing or as a cleaning agent instead.
13. Line the soap mold with wax paper (unless using a waxed milk or
juice carton).
14. Pour the soap mixture into a mold and allow to set for at least 24
hours.
15. The soap can be removed from the mold and sliced after 1 day, but
should be allowed to cure for 2 weeks before using.
16. Observe the characteristics of your soap, such as texture and
odor. After the soap has cured for a few weeks, test its lathering
capabilities.
Analysis
1. What were the indications that a chemical reaction occurred in this
experiment?
2. Describe the appearances of the lye solution and the oil solution
before they were mixed. How did that change after they were
combined?
3. How did the phenolphthalein react with the lye solution? With your
soap solution?
4. What did the color of the phenolphthalein indicate about the pH of
the solutions as the reaction progressed?
