Easy⏱ time15 min$ cost4
Cold Pack Reaction
Mix two everyday chemicals and feel the cup turn icy — an endothermic reaction in your hand.
Start building ↓
Result first
The build
Step 01
Record start temp
Measure the water temperature.
Step 02
Add citric acid
Stir citric acid into the water.
Step 03
Add baking soda
Mix in baking soda and stir.
Step 04
Feel the chill
The cup cools as you watch the thermometer drop.
Working Principle
The reaction absorbs heat from its surroundings to proceed, so the mixture and cup get colder — the opposite of a volcano's warmth.
The science behind it
A closer look
Endothermic reactions take in energy; the temperature drop measures how much heat the reaction pulls from the water.
Take it further
Variables to test
- 1 Vary the amounts — how low can you get the temperature?
- 2 Compare this with an exothermic reaction's rise.
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