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Cold packs and hot packs

Some substances make water colder when they dissolve, others make it warmer.

Topic: First chemistry (grades 7–8)Grade: 7Free

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What you do

  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!

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