Chemistry is an integral part of our lives. Consciously or unconsciously we interact with a lot of chemicals and processes (chemical or physical) every day. To help a group of young students (of class 7 and 8 from the Government Girls Upper Primary School, Damta, Uttarkashi) understand this importance of chemistry in our lives I got them to do a couple of experiments which I would like to share with you through this article.
Before carrying out the experiment, I arranged for the following materials and reading resources:
• Wooden stick
• Indigo blue (Ujala)
• Chalk pieces
• 10 plastic disposable cups
Reading resources to enhance my understanding of what the students are learning:
• Uttarakhand State textbook
• NCERT textbook
• YOUTUBE videos
I divided the students into four groups and asked them to list the substances that they thought would dissolve in another substance, say water. This was their list:
• Cold drink
• Tea leaves
• Mango shake
Their list told me that these students were unsure of the solubility of some substances. For instance, while some believed that oil would dissolve in water some did not. Similarly detergent and honey too. The best way for them to learn about solubility was for them to experiment and find out so I gave each group some materials for the group activity.
Groups 1 and 2: Sand, soil, water and two plastic disposable cups
Groups 3 and 4: Sugar, salt, water and two plastic disposable cups
I asked the groups to mix these substances and note down their observations. Groups 1 and 2 mixed sand in water and soil in water. Groups 3 and 4 mixed sugar in water and salt in water. Their observations were as follows:
- We took some amount of water in a plastic cup and added some soil, suddenly the water turned brown.
- When we added sand in water, after some time it settled down. The colour of water changed to gray.
- We took a little sugar in a cup and then poured water on it. The colour changed a little bit.
- We took water and then added salt in it; on doing this the large amount of salt got dissolved in water but some amount didn’t. We stirred this with a pen and saw that all the salt dissolved. The colour was much the same as that of ordinary water.
From this experiment the students learnt that they were able to see soil and sand in water but not sugar and salt so would it be right to say…
The author is with the Azim Premji Foundation. He can be reached at firstname.lastname@example.org.