How to make a chemical heating pad

Using a chemical reaction to get warm

Just a small heat­ing pad to warm your hands this win­ter!

Safe­ty pre­cau­tions

Per­form this ex­per­i­ment only un­der adult su­per­vi­sion.


  • re­seal­able bag;
  • min­er­al filler;
  • zinc pow­der;
  • cop­per sul­fate;
  • sy­ringe;
  • wa­ter.

Step-by-step in­struc­tions

Put some zinc pow­der, cop­per sul­fate, and min­er­al filler in a re­seal­able bag. Mix thor­ough­ly and add some wa­ter with a sy­ringe. Your heat­ing pad is ac­ti­vat­ed!

Pro­cess­ de­scrip­tion

Zinc is a rather re­ac­tive met­al, and read­i­ly forces less re­ac­tive met­als from their salts. The cop­per sul­fate, and the cop­per in its com­po­si­tion, is one such ex­am­ple. Adding wa­ter ini­ti­ates a re­ac­tion in which zinc re­places the cop­per ions in the sul­fate, yield­ing a cop­per pre­cip­i­tate. This re­ac­tion also re­leas­es heat, and as the zinc is pow­dered, the re­ac­tion pro­ceeds quick­ly enough to gen­er­ate a large amount of heat in a short time.

A sim­i­lar ex­per­i­ment is in­clud­ed in the “Ther­mal ef­fects” kit from the MEL Chem­istry sub­scrip­tion.