Dissolving in Water

Looking Around 2 — kitchen activities such as making sherbet or salt water, where things seem to "disappear" into water.

• Some things dissolve in water — they spread through it and you cannot see them anymore, like salt or sugar.
• Some things do not dissolve — like sand or oil — they stay separate.
• Dissolved things are still there, just too tiny to see.

Verbal: When a solid dissolves, it mixes so completely with water that you cannot see it, but you can still taste it.

Symbolic: Salt + Water (stirred) → Salt water (salt still present, just spread out).

Level 1 — Things that dissolve

Salt, sugar, and glucose powder dissolve in water.

Level 1 — Things that do NOT dissolve

Sand, chalk powder, and oil do not dissolve in water.

Level 1 — How do we know it dissolved?

Level 2 — Stirring helps

Stirring makes things dissolve faster.

Level 2 — India

Making nimbu paani (lemon water) — sugar and salt dissolve in water with lemon juice.

You add a spoon of sugar to a glass of water and stir. What happens?

Step 1 — Sugar grains spread through the water while stirring.
Step 2 — After a while, you cannot see sugar grains.
Step 3 — The water tastes sweet — sugar is still there, dissolved.
Answer: Sugar dissolved in the water.

• Name two things that dissolve in water.
• Name one thing that does NOT dissolve in water.
• Why does stirring help sugar dissolve faster?

Stretch: Does hot water help sugar dissolve faster than cold water?

Revision tip: Try mixing salt, sand, and sugar (separately) in three glasses of water and observe.

Open the Practice tab for graded questions on Dissolving in Water.