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Investigating why some solids seem to disappear when stirred into water.
Have you ever stirred a spoonful of sugar into a drink and watched it vanish like a magic trick? Where does it go, and is it really gone forever?
When we put a solid (like salt) into a liquid (like water) and stir, sometimes the solid seems to disappear. This is called dissolving. When a solid dissolves, it breaks into tiny pieces that are too small for our eyes to see. These tiny pieces spread out all through the water. The special mixture we make is called a solution. Even though the water looks clear, the solid is still hiding inside!
Let's look at what happens with salt: 1. Take a glass of clear water. 2. Add teaspoon of white salt. 3. Stir the water with a spoon. 4. Watch as the white grains get smaller and smaller until they vanish!
Quick Check
What is the scientific word for when a solid mixes so well into a liquid that it 'disappears'?
Answer
Dissolving
Not everything can perform this magic trick! Some things, like sugar and salt, are soluble. This means they are 'able to dissolve.' Other things, like sand or rocks, are insoluble. No matter how much you stir sand, it will just sink to the bottom or make the water cloudy. It will never break down into tiny enough pieces to dissolve.
Imagine you are at the beach. 1. You put a handful of sand into a bucket of water. 2. You stir for minutes. 3. The water looks messy, but the sand is still there! This is because sand is insoluble.
Quick Check
If you stir a spoonful of sand into water, will it dissolve?
Answer
No, because sand is insoluble.
How do we know the sugar is still there if we can't see it? We can use our senses and science tools! If you taste the water, it will be sweet. Also, the sugar adds mass (weight) to the water. If you weigh the water before and after, the weight goes up!
What do we call a solid that is ABLE to dissolve?
Which of these will dissolve in water?
When sugar dissolves in water, the sugar is gone forever.
Review Tomorrow
In 24 hours, try to explain to a friend what 'soluble' means and give one example from your kitchen.
Practice Activity
Kitchen Science: With an adult, try dissolving different things in water (flour, pepper, salt, honey). Make a list of which ones are soluble!