Sugar and Salt Dissolve in Water
Atlas stands at a sunny kitchen table with two clear glasses of water, a small spoon, a bowl of white sugar, and a shaker of salt. Atlas stirs one glass and watches closely as the sugar vanishes into the water, grinning with delight.
- Identify what happens to sugar or salt when it is stirred into water.
- Explain that dissolved sugar or salt is still in the water even when you cannot see it.
- Predict whether stirring will make a solid dissolve faster.
Key terms
- dissolve
- when a solid spreads through water in pieces too tiny to see
- solid
- matter that keeps its shape, like a grain of sugar or salt
- mixture
- two things combined, like sugar spread all through water
- stirring
- moving water with a spoon to help a solid dissolve faster
Where Does the Sugar Go
When you drop sugar into water and stir, the sugar seems to vanish, but it does not really go away. The sugar breaks into pieces so tiny that your eyes cannot see them, and those pieces spread out evenly through every drop of the water. This spreading out is called dissolving. The sugar is still there the whole time; it has just become invisible inside the water.
How We Know It Is Still There
Even though you cannot see the dissolved sugar, there are ways to prove it stayed in the water. If you tasted the water, it would taste sweet, and that sweetness comes from the sugar spread through it. Salt works the same way and would make the water taste salty. The taste is proof that dissolving spreads a solid through water instead of destroying it.
Stirring Speeds It Up
Stirring the water with a spoon helps a solid dissolve much faster than just letting it sit. When you stir, the moving water bumps into the sugar and carries the tiny pieces away quickly, so they spread out sooner. Without stirring, the sugar still dissolves, but it takes more time. So if you want sweet water in a hurry, give it a good spin with your spoon.
Worked examples
Predict what happens when you stir salt into a glass of water.
- Salt is a solid that can dissolve, just like sugar.
- Stirring carries the tiny salt pieces all through the water.
- The salt spreads out and disappears from view, making the water taste salty.
Answer: The salt dissolves and spreads through the water, which would then taste salty.
Activity
Drag each solid into the glass of water and watch what happens when you stir
Practice
Predict whether stirring makes sugar dissolve faster or slower.
Explain how you could prove dissolved salt is still in the water.
Common mistakes to avoid
- Dissolved sugar turns into water.The sugar does not become water; it stays sugar and just spreads through the water in tiny pieces.
- Dissolving makes the sugar disappear forever.The sugar is still in the water, which is why the water tastes sweet even though you cannot see it.
Check your understanding
You put sugar in water and stir. The sugar seems to disappear. Where did the sugar go?
You dissolve sugar in water. How can you tell the sugar is still there?
What happens if you stir the water after dropping in sugar?
Recap
When sugar or salt dissolves in water, it breaks into pieces too tiny to see and spreads through every drop. The solid is still there, which is why the water tastes sweet or salty, and stirring helps it dissolve faster.
Reflect
What is something you have watched dissolve in a drink?