Soap making in the classroom

V. Jayasundhar

Samacheer , Term - III, Class - VI

Young chemists at work

Chemistry is an inevitable part of our everyday lives. Today, we find the influence of chemistry in many aspects of our lives ranging from food to medicine to personal care products. The lesson on ‘Chemistry in our Daily Life’, deals with topics like fabric, cement, glass, plastics, soap - some man-made materials which are commonly used and their application.

       I thought it would be interesting to engage students in an activity on the preparation of soap as it would give students a first-hand experience in making soaps. The activity was an opportunity not just to teach the process of making soaps, but also certain other basic concepts in chemistry. They also learnt about the ingredients involvedin making a soap and its significance. The activity was spread out over a couple of days and children were very excited at the thought of making their own soaps. 

Making the Soap
Materials Required:
Water, Sodium hydroxide, Coconut oil, essential oils like rose/lemon/lavender etc.
Process:
Note: Ensure that the entire process is carried out under the supervision of the teacher and students are not left to handle chemicals on theirown.
We took a stainless steel bowl with water and heated it on the stove. Once the water began to Young chemists at work V. Jayasundhar boil, we slowly added sodium hydroxide into it and stirred it continuously. (For 50ml of water, add 14g of NaOH). Once when NaOH is completelydissolved in water, we s w i t c h e d off the gasand kept the solution aside and allowed it to cool. We tried out two different oils – coconut oil and olive oil to prepare soaps. We took 85g coconut oil in one bowl and olive oil in another and heated it to its melting point. After that, we added sodium hydroxide solution to the oil mixture stirred it for 10 to 15 minutes until it became thick like a paste. We then added the essential oils for fragrance and poured this mixture into moulds after they came to room temperature. (Children had brought empty match boxes to be used as moulds). We let it dry ofr 24 to 36 hours.

Reflections:
Students were very involved in the activity and their interest levels were high throughout. At each step, there was a discussion that followed that helped students understand the process better. For instance, while dissolving sodium hydroxide, they learnt that the pellets have to be added in hot water and stirred continuously to avoid it from becoming hard. Students noticed that oil is solidified at lower temperatures and it is required to heat it to bring it to its liquid form. Students could easily relate to this idea as it has been their experience during winters. We had a discussion on solubility of liquids when we mixed the solutions as students can see for themselves that oil is not
soluble in water and an emulsion is being formed. My students carried the notion that soaps always had some color in it until they say that the soaps they made were white in color. I used this as the opportunity to explain the role of coloring agentsand essential oils to give color andfragrance.
Additional discussions on the difference between bath soaps and washing soaps can be done with students and they can also conduct a survey to find out why some soaps are preferred over others.