First chemistry (grades 7–8) · Grade 7
Cold packs and hot packs
ChemAI · Worksheet
NameClassDate
Aim
Some substances make water colder when they dissolve, others make it warmer.
Before you start: what do you predict will happen? Why?
What you do
| Step | What I observed | |
|---|---|---|
| 1 | Add ammonium nitrate to beaker 1 (it is used in instant cold packs). Watch the thermometer. | |
| 2 | Add sodium hydroxide pellets to beaker 2. Careful: it is corrosive — and it gets warm! |
Questions
- Write a word or symbol equation for one reaction you observed.
- Explain your most important observation using particles, ions or energy.
- Was your prediction right? What would you change to get a more reliable result?