Lesson 6.11: Chemical Reactions & Engineering Design

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Three Types of Heat Packs

• The first contains a fine iron powder, salt, and water in a pouch that is permeable to air. When it is exposed to air, the iron begins to rust. This rusting process produces heat.
• The second contains a solution of the chemical sodium acetate and a small metal disc. When the disc is bent, crystals of sodium acetate begin to form. This process of changing from a liquid to a solid produces heat.
• The third contains a type of magnesium sulfate, and a pouch of water. When the pouch is broken, the water begins to dissolve the magnesium sulfate. Dissolving this type of magnesium sulfate produces heat.