Experiment 6 — The Dissolving Race

Topic: Chemistry · Classes 4–5 · Solutions: soluble and insoluble substances

Aim: Dissolve the sugar completely in under 30 seconds.

Daily: You do this every morning: sugar in tea dissolves faster when the tea is hot and you stir it. Powdered spices release flavour faster than whole ones for the very same reason.

Obs: The sugar dissolved completely in

Question: Which single change speeds up dissolving the most?

Exp: Powder exposes far more surface to the water than one lump.

Question: Sugar “disappears” in water. Where has it gone?

Exp: It dissolved. Evaporate the water and it returns.

Exp: Stirring removes the saturated layer around each crystal.

Question: For a fair test of temperature only, what stays the same?

Exp: Change one variable at a time.

Exp: Salt dissolves; sand settles and oil separates.