Lab Report Soap Making

[Chemistry 2] Experiment No. 2

ACID-BASE TITRATION M.V.L LIM, J. JANEA, L.V. MEDRANO, J.M. OLARITA, AND C. ZOZOBRADO X- Gluon Philippine Science High School – Central Visayas Campus Talaytay, Argao, Cebu Date Performed: January 22, 2016 Date Submitted: February 10, 2016

ABSTRACT Soap is one of the commercial products essential to our health as it promotes cleanliness and preserves our skin from the scorching heat of the sun and from external pollution such as dust, germs, and bacteria. Learning how to make soap and the chemistry behind it is as important as its benefit. In order to make basic soap, an experiment was performed, dealing with the process of saponification, a process that produces soap, usually from fats and lye. In the experiment, the fats used were common oils, such as olive oil, vegetable oil, and unsalted butter, whereas the lye used was sodium hydroxide (NaOH). The fats, which are the acids and the lye, which is the base underwent saponification to form a glycerin and a salt, which is the soap, the final product of the experiment.

INTRODUCTION Straight-chain monocarboxylic acids, called fatty acids, are seldom found as free molecules in nature but are most often a part of a larger molecule called a triglyceride. Soap is produced by the process of saponification, or the hydrolysis of a triglyceride, the fats and oil, to produce glycerol and fatty acid salts from the reaction of the triglyceride with a strong base such as sodium or potassium hydroxide. The bond between the fatty acid and the glycerol backbone is referred to as an

ester

linkage.

In

the

saponification process, as shown in Figure 1, the ester linkage is broken to form glycerol and soap. [1] Figure 1. Saponification of a triglyceride In the experiment, the oils used were olive oil, vegetable oil and butter while the base used was sodium hydroxide. Sodium hydroxide (NaOH) was

preferred over potassium hydroxide (KOH) because the aim was to make a bar soap rather than a liquid soap. Also, the hot process method was preferred over the cold process due to insufficient amount of time, as cold process soap take a longer time to harden or cure than hot process soap. The hot process uses heat to speed the reaction resulting in fully saponified soap by the time the soap is poured into molds. The group’s experiment consisted of two trials, the first one being a failure. Following the hot process procedure, 50 g of olive oil and 50 g of unsalted butter were heated and mixed thoroughly. The amount of lye was calculated by totaling the amount of fats in grams and multiplying it by 13 %, yielding an amount of 13 g. The ratio for the amount of lye to water used was 1:1, 13 g of tap water was also used. Two grams of vanilla was used. Table 1 depicts the ingredients used and its corresponding amounts. [2] Table 1. Amounts for ingredients used Poun Ounc Gra ds es ms Water 0.028 0.44 12.56 Lye (NaOH) 0.028 0.44 12.56 Oils 0.220 3.53 100.0 0 Fragrance 0.004 0.07 2.00 The lye was carefully poured to the water and was mixed using a stirring rod. At the same time, the oil mixture was heated in a hot pot to 33-43°C and was constantly stirred. When the mixture was viscous enough, the solution of NaOH and water was added while ceaselessly stirring. The mixture

was continually stirred until it began to thicken. During this stage, the vanilla was now added and mixed scrupulously. When the mixture was already thick and viscous, it was bathed in cold running water to cool its temperature. Afterwards, the mold was prepared using empty water bottles and a tray-like container, greased with plastic wrap, and the mixture was poured. About 6 hours passed and two soap bars were produced.

RESULTS AND DISCUSSION Soap is formed through the process of saponification where fats and oils are treated with strong bases such as lye (NaOH) or potash (KOH) to form glycerol and the salt of a longchain fatty acid (soap), as shown previously in Figure 1. There are two methods used to prepare soap, the hot process and cold process. Both require a heat source and careful calculations to ensure that no caustic base is left unreacted in the soap. The hot process uses heat to speed the reaction resulting in fully saponified soap by the time you pour your soap into molds. The cold process uses just enough heat to ensure that all the fat is melted prior to reacting it with the base. The first trial of making the soap was a failure because the measurements weren’t exact and the other ingredients weren’t measured properly. The amount of oil used exceeded 100% thus the ratio was wrong which resulted to a soap which

is too basic and a soap that is too soft. Another contributing factor to its basicity was that 5 % excess of the oil was not applied that only little sodium hydroxide is consumed in the saponification process. The soap was tested and burned a skin, thus the soap isn’t advisable to be used and applied to the skin. Due to the first soap being a failure, another one was made through the same process but with concise measurements, which was a success since the ratio between the ingredients were calculated and added carefully, in order to avoid failures. The soap produced took a longer time to harden, because olive oil bars also take considerably longer to react. The soap from olive oil, however, was softer and can be a good moisturizer. The length of the hydrocarbon chain and number of double bonds in the carboxylic acid salt of the carboxylic acid portion of the fat or oil determine the properties of the resulting salt. For example, the salt of a saturated long chain acid make a harder, more insoluble soap. [3]. SUMMARY AND CONCLUSIONS In its overall, the experiment semi-succeeded in yielding a partiallyhardened soap through the traditional hot process method where oils and fats are mixed with a solution of sodium hydroxide. In this experiment, the triglyceride (oils and fats) is reacted with a strong base (lye) to

produce glycerol and fatty acid salts (soap). The aforementioned process is called saponification, the main process in making soaps, where the principal acids are hydrolyzed. The conducted experiment produced a soft soap with excess oil and vanilla scent, but due to lack of time, it wasn’t able to harden. Hence, the soap, Kurislim, wasn’t good enough to compete with commerciallyprepared soaps.

REFERENCES [1] Chemistry 122: Synthesis of Soap. (n.d.). Retrieved September 19, 2015, from https://hoeggerfarmyard.com/thefarmyard/soap-making2/saponification-explained/

[2] Retrieved September 19, 2015, from http://soapcalc.net

[3] Fisher, D. (n.d.). Olive Oil (Castile) Soap Recipes. Retrieved September 20, 2015, from http://candleandsoap.about.com/od/s oaprecipes/a/castrecipe.htm

APPENDIX RAW DATA Table 1. Amounts for ingredients used Pounds

Ounces

Grams

Water

0.028

0.44

12.56

Lye (NaOH)

0.028

0.44

12.56

Oils

0.220

3.53

100.00

Fragrance

0.004

0.07

2.00

Figure 2. Set-up for basic soap making