You Will Need:
- Adult help
- Three cups of table salt.
- 1L of water
- One Pencil
- 1 Paperclip
- A piece of string, cut to size.
- One strong plastic or Pyrex jar.
Boil the water with the help of an adult.
Pour the water into the plastic jar. Do not use glass as it may break.
Add the salt one table spoon at a time. Allowing the salt to dissolve before you add more table spoons.
Continue adding salt until you cannot dissolve anymore and it collects at the bottom of the jar.
Tie one end of the string around the pencil and the other end around the paperclip.
Dangle the string into the saturated salt solution, so that the paperclip doesn’t touch the bottom of the jar or its sides.
Allow the jar to sit undisturbed for one week. Salt crystals should form at the top of the string
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Why Does This Happen:
The crystals could only stay dissolved when the water was hot. Cooling the solution down made it supersaturated, which is unstable. You should have found that the water travelled up the string through a process called capillary action, bringing the salt with it. As the water evaporated on the string, salt crystals were left behind.
A supersaturated solution is a solution that has more material dissolved in it then it would normally allow.
Find out more about capillary action on the external site USGS Water Science.
Variables to test
- Try using epsom salts or sugar instead of table salt. Do you get the same effect?
- Try cold vs. hot water as a comparison
- Does it matter which substrate that you form the crystals on?
From colour changes to slimy science, we’ve got your kitchen chemistry covered!
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Will the color change if you add food color?
They should do, give it a try! Have a fun 🙂
Can u use sugar not salt
Sure thing! Just be careful of the hot sugar syrup. Compare these sugar crystals with the salt crystals.