Home­made hand­warm­ers will keep frost­bite from your fin­gers

Medicine Hat News - - YOUTH - Patty Rooks

Brrr…it is cold out­side this week. I think that win­ter has fi­nally ar­rived here in south­ern Al­berta. There are many ways to keep warm while you are out­side en­joy­ing the win­ter weather. This week, I thought I’d share how to make your own hand­warm­ers to keep your fin­gers warm and toasty! Let’s get started!

*Re­mem­ber to ask an adult be­fore do­ing this ex­per­i­ment.


zip­per sand­wich bag iron fil­ings (pur­chase at the hard­ware store) mea­sur­ing spoons mea­sur­ing cups warm wa­ter wa­ter ab­sorb­ing crys­tals (pur­chase at craft store)

cal­cium chlo­ride (in the spice or pick­ling sec­tion at gro­cery store or in “ice melter”) per­ma­nent marker gog­gles


1. Put on your safety gog­gles.

2. Write on your bag – SCI­ENCE EX­PER­I­MENT DO NOT EAT. Set aside for now.

3. Mea­sure one cup (250 mL) of wa­ter and add 1/2 tea­spoon (2.5 mL) of the wa­ter ab­sorb­ing crys­tals. Al­low this to sit for a lit­tle while (prefer­ably overnight). 4. Ob­serve now and again. 5. What is go­ing on? 6. Mea­sure 1/4 cup (60mL) of the hy­drated wa­ter ab­sorb­ing crys­tals to the zip­per bag­gie.

7. Add one ta­ble­spoon (15 mL) of iron fil­ings to the bag­gie.

8. Mea­sure two ta­ble­spoons (30 mL) of cal­cium chlo­ride to the bag­gie as well. 9. Zip the bag­gie up tight. 10. Squish it all around so you can mix the en­tire con­tents of the bag.

11. Once ev­ery­thing is mixed up well, squish ALL of the air out of the bag­gie and zip back up.

12. Roll the bag back and forth be­tween your fin­gers.

13. What do you feel?

14. Put this in your pocket on a cold day to keep you warm!

What is go­ing on?

First of all, you prob­a­bly wit­nessed some­thing pretty amaz­ing if you ob­served the wa­ter ab­sorb­ing crys­tals at all. The wa­ter ab­sorb­ing crys­tals are quite an in­ter­est­ing sub­stance as they will grow to quite a large size – per­haps even over­flow the con­tainer they are in. This is be­cause they are made with a su­per­ab­sorbent poly­mer and when hy­drated (added to wa­ter) grow and grow.

As you rub the bag­gie, it will be­gin to feel hot due to the chem­i­cal re­ac­tion that is tak­ing place. First, a bit of back­ground. The re­ac­tion in this ex­per­i­ment starts with rust. Rust­ing is an ex­am­ple of cor­ro­sion as the iron metal be­gins to break down. The re­ac­tants in this chem­i­cal re­ac­tion are iron, wa­ter and oxy­gen and the prod­uct or re­sult is iron ox­ide which we com­monly know as rust. In this ex­per­i­ment the wa­ter ab­sorb­ing crys­tals pro­vide the nec­es­sary wa­ter to the iron fil­ings in or­der to start the chem­i­cal re­ac­tion of rust­ing. You fur­ther add cal­cium chlo­ride which fur­ther pro­duces an exother­mic re­ac­tion or pro­duces the heat you feel. Pretty in­ter­est­ing re­ac­tion from just a few house­hold ma­te­ri­als. I hope that these will keep you warm this win­ter!

Did you know that you could eas­ily make this into a great sci­ence ex­per­i­ment? What if you var­ied the amount of cal­cium chlo­ride or the amount of iron fil­ings – would it af­fect the amount of time the hand warmer stays hot? Give it a try!

Teach­ers - if your school is in­ter­ested in hav­ing a sci­ence fair club, make sure you call soon so I can pop by and give you some great point­ers!

Patty Rooks is se­nior sci­en­tific con­sul­tant at PRAXIS, “Con­nect­ing Sci­ence To The Com­mu­nity.” Con­tact Praxis at [email protected]­ismh.ca, www.prax­ismh.ca, Tweet or fol­low us @Prax­isMedHat, or friend us on Face­book.

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