BY : Nisreen Sherawala, year 6
Science is everywhere around us in our daily lives. If we look carefully, there is science in eating, breathing, driving, playing and even cooking.
We have an old ice cream churner at home and it requires ice and salt to be added in layers in the outer compartment. I wondered why this was done so I googled and came to know that adding salt to ice lowers its freezing point and makes it stay colder for longer.
To test this out, I carried out an experiment to see if this was really true.
I started with a cube of ice, a piece of string, a glass half filled with water at room temperature and salt.
I added the ice cube to the glass containing water.
I tried to swirl the string around the ice cube to see if I could lift up the ice with the string. It did not hold.
I added salt on top of the bits of the ice where the string was touching the ice and waited a few minutes without moving the string around at all.
After a while, I gently lifted the string up and to my surprise I could lift the ice cube with it, it had almost glued together!
This happened because when you sprinkle salt over ice it dissolves in the thin layer of water above the ice. Because saltwater freezes at a lower temperature than pure water adding the salt makes some ice melt and absorb heat in the process. The area just around it thereby cools and freezes water molecules to the ice cube, also freezing the string on.
This is one of the ways we actually use science in our daily lives without realising.