Hooked on Science: Hot ice

Materials

• Reusable hand warmer
• Paper plate
• Scissors

Instructions

• STEP 1: Without clicking the metal disk inside the hand warmer, observe its contents. Describe and classify the contents of the hand warmer by its observable properties.
• STEP 2: Using the scissors, cut open the hand warmer. Quickly pour the contents onto the paper plate and observe. Touch the contents of the hand warmer on the plate. Describe and classify the contents of the hand warmer while on the paper plate by its observable properties.

Explanation

Reusable hand warmers contain a super-saturated solution of water and sodium acetate. Once you click the metal disk inside the hand warmer or the contents hit the paper plate, a chain reaction is triggered, which causes the solution to crystallize. As a result, an exothermic reaction happens, which gives off heat.